citus/src/backend/distributed/planner/multi_physical_planner.c

5498 lines
169 KiB
C

/*-------------------------------------------------------------------------
*
* multi_physical_planner.c
* Routines for creating physical plans from given multi-relational algebra
* trees.
*
* Copyright (c) 2012, Citus Data, Inc.
*
* $Id$
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <math.h>
#include "access/genam.h"
#include "access/hash.h"
#include "access/heapam.h"
#include "access/nbtree.h"
#include "access/skey.h"
#include "catalog/pg_am.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/sequence.h"
#include "distributed/listutils.h"
#include "distributed/citus_nodefuncs.h"
#include "distributed/citus_nodes.h"
#include "distributed/citus_ruleutils.h"
#include "distributed/master_metadata_utility.h"
#include "distributed/master_protocol.h"
#include "distributed/metadata_cache.h"
#include "distributed/multi_logical_optimizer.h"
#include "distributed/multi_logical_planner.h"
#include "distributed/multi_physical_planner.h"
#include "distributed/pg_dist_partition.h"
#include "distributed/pg_dist_shard.h"
#include "distributed/task_tracker.h"
#include "distributed/worker_manager.h"
#include "distributed/worker_protocol.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/predtest.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/var.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/typcache.h"
/* Policy to use when assigning tasks to worker nodes */
int TaskAssignmentPolicy = TASK_ASSIGNMENT_GREEDY;
/*
* OperatorCache is used for caching operator identifiers for given typeId,
* accessMethodId and strategyNumber. It is initialized to empty list as
* there are no items in the cache.
*/
static List *OperatorCache = NIL;
/* Local functions forward declarations for job creation */
static Job * BuildJobTree(MultiTreeRoot *multiTree);
static MultiNode * LeftMostNode(MultiTreeRoot *multiTree);
static Oid RangePartitionJoinBaseRelationId(MultiJoin *joinNode);
static MultiTable * FindTableNode(MultiNode *multiNode, int rangeTableId);
static Query * BuildJobQuery(MultiNode *multiNode, List *dependedJobList);
static Query * BuildReduceQuery(MultiExtendedOp *extendedOpNode, List *dependedJobList);
static List * BaseRangeTableList(MultiNode *multiNode);
static List * QueryTargetList(MultiNode *multiNode);
static List * TargetEntryList(List *expressionList);
static List * QueryGroupClauseList(MultiNode *multiNode);
static List * QuerySelectClauseList(MultiNode *multiNode);
static List * QueryJoinClauseList(MultiNode *multiNode);
static List * QueryFromList(List *rangeTableList);
static Node * QueryJoinTree(MultiNode *multiNode, List *dependedJobList,
List **rangeTableList);
static RangeTblEntry * JoinRangeTableEntry(JoinExpr *joinExpr, List *dependedJobList,
List *rangeTableList);
static int ExtractRangeTableId(Node *node);
static void ExtractColumns(RangeTblEntry *rangeTableEntry, int rangeTableId,
List *dependedJobList, List **columnNames, List **columnVars);
static RangeTblEntry * DerivedRangeTableEntry(MultiNode *multiNode, List *columnNames,
List *tableIdList);
static List * DerivedColumnNameList(uint32 columnCount, uint64 generatingJobId);
static Query * BuildSubqueryJobQuery(MultiNode *multiNode);
static void UpdateColumnAttributes(Var *column, List *rangeTableList,
List *dependedJobList);
static Index NewTableId(Index originalTableId, List *rangeTableList);
static AttrNumber NewColumnId(Index originalTableId, AttrNumber originalColumnId,
RangeTblEntry *newRangeTableEntry, List *dependedJobList);
static Job * JobForRangeTable(List *jobList, RangeTblEntry *rangeTableEntry);
static Job * JobForTableIdList(List *jobList, List *searchedTableIdList);
static List * ChildNodeList(MultiNode *multiNode);
static uint64 UniqueJobId(void);
static Job * BuildJob(Query *jobQuery, List *dependedJobList);
static MapMergeJob * BuildMapMergeJob(Query *jobQuery, List *dependedJobList,
Var *partitionKey, PartitionType partitionType,
Oid baseRelationId,
BoundaryNodeJobType boundaryNodeJobType);
static uint32 HashPartitionCount(void);
static int CompareShardIntervals(const void *leftElement, const void *rightElement,
FmgrInfo *typeCompareFunction);
static ArrayType * SplitPointObject(ShardInterval **shardIntervalArray,
uint32 shardIntervalCount);
/* Local functions forward declarations for task list creation */
static Job * BuildJobTreeTaskList(Job *jobTree);
static List * SubquerySqlTaskList(Job *job);
static List * SqlTaskList(Job *job);
static bool DependsOnHashPartitionJob(Job *job);
static uint32 AnchorRangeTableId(List *rangeTableList);
static List * BaseRangeTableIdList(List *rangeTableList);
static List * AnchorRangeTableIdList(List *rangeTableList, List *baseRangeTableIdList);
static void AdjustColumnOldAttributes(List *expressionList);
static List * RangeTableFragmentsList(List *rangeTableList, List *whereClauseList,
List *dependedJobList);
static OperatorCacheEntry * LookupOperatorByType(Oid typeId, Oid accessMethodId,
int16 strategyNumber);
static Oid GetOperatorByType(Oid typeId, Oid accessMethodId, int16 strategyNumber);
static Node * HashableClauseMutator(Node *originalNode, Var *partitionColumn);
static bool OpExpressionContainsColumn(OpExpr *operatorExpression, Var *partitionColumn);
static Var * MakeInt4Column(void);
static Const * MakeInt4Constant(Datum constantValue);
static OpExpr * MakeHashedOperatorExpression(OpExpr *operatorExpression);
static OpExpr * MakeOpExpressionWithZeroConst(void);
static List * BuildRestrictInfoList(List *qualList);
static List * FragmentCombinationList(List *rangeTableFragmentsList, Query *jobQuery,
List *dependedJobList);
static JoinSequenceNode * JoinSequenceArray(List *rangeTableFragmentsList,
Query *jobQuery, List *dependedJobList);
static bool PartitionedOnColumn(Var *column, List *rangeTableList, List *dependedJobList);
static void CheckJoinBetweenColumns(OpExpr *joinClause);
static List * FindRangeTableFragmentsList(List *rangeTableFragmentsList, int taskId);
static bool JoinPrunable(RangeTableFragment *leftFragment,
RangeTableFragment *rightFragment);
static ShardInterval * FragmentInterval(RangeTableFragment *fragment);
static StringInfo FragmentIntervalString(ShardInterval *fragmentInterval);
static List * UniqueFragmentList(List *fragmentList);
static List * DataFetchTaskList(uint64 jobId, uint32 taskIdIndex, List *fragmentList);
static StringInfo NodeNameArrayString(List *workerNodeList);
static StringInfo NodePortArrayString(List *workerNodeList);
static StringInfo DatumArrayString(Datum *datumArray, uint32 datumCount, Oid datumTypeId);
static Task * CreateBasicTask(uint64 jobId, uint32 taskId, TaskType taskType,
char *queryString);
static void UpdateRangeTableAlias(List *rangeTableList, List *fragmentList);
static Alias * FragmentAlias(RangeTblEntry *rangeTableEntry,
RangeTableFragment *fragment);
static uint64 AnchorShardId(List *fragmentList, uint32 anchorRangeTableId);
static List * PruneSqlTaskDependencies(List *sqlTaskList);
static List * AssignTaskList(List *sqlTaskList);
static bool HasMergeTaskDependencies(List *sqlTaskList);
static List * AssignAnchorShardTaskList(List *taskList);
static List * GreedyAssignTaskList(List *taskList);
static Task * GreedyAssignTask(WorkerNode *workerNode, List *taskList,
List *activeShardPlacementLists);
static List * RoundRobinAssignTaskList(List *taskList);
static List * RoundRobinReorder(Task *task, List *placementList);
static List * ReorderAndAssignTaskList(List *taskList,
List * (*reorderFunction)(Task *, List *));
static int CompareTasksByShardId(const void *leftElement, const void *rightElement);
static List * ActiveShardPlacementLists(List *taskList);
static List * ActivePlacementList(List *placementList);
static List * LeftRotateList(List *list, uint32 rotateCount);
static List * FindDependedMergeTaskList(Task *sqlTask);
static List * AssignDualHashTaskList(List *taskList);
static int CompareTasksByTaskId(const void *leftElement, const void *rightElement);
static void AssignDataFetchDependencies(List *taskList);
static uint32 TaskListHighestTaskId(List *taskList);
static List * MapTaskList(MapMergeJob *mapMergeJob, List *filterTaskList);
static char * ColumnName(Var *column, List *rangeTableList);
static StringInfo SplitPointArrayString(ArrayType *splitPointObject,
Oid columnType, int32 columnTypeMod);
static List * MergeTaskList(MapMergeJob *mapMergeJob, List *mapTaskList,
uint32 taskIdIndex);
static StringInfo ColumnNameArrayString(uint32 columnCount, uint64 generatingJobId);
static StringInfo ColumnTypeArrayString(List *targetEntryList);
static StringInfo MergeTableQueryString(uint32 taskIdIndex, List *targetEntryList);
static StringInfo IntermediateTableQueryString(uint64 jobId, uint32 taskIdIndex,
Query *reduceQuery);
static uint32 FinalTargetEntryCount(List *targetEntryList);
/*
* MultiPhysicalPlanCreate is the entry point for physical plan generation. The
* function builds the physical plan; this plan includes the list of tasks to be
* executed on worker nodes, and the final query to run on the master node.
*/
MultiPlan *
MultiPhysicalPlanCreate(MultiTreeRoot *multiTree)
{
MultiPlan *multiPlan = NULL;
StringInfo jobSchemaName = NULL;
Job *workerJob = NULL;
uint64 workerJobId = 0;
Query *masterQuery = NULL;
List *masterDependedJobList = NIL;
/* build the worker job tree and check that we only one job in the tree */
workerJob = BuildJobTree(multiTree);
/* create the tree of executable tasks for the worker job */
workerJob = BuildJobTreeTaskList(workerJob);
workerJobId = workerJob->jobId;
/* get job schema name */
jobSchemaName = JobSchemaName(workerJobId);
/* build the final merge query to execute on the master */
masterDependedJobList = list_make1(workerJob);
masterQuery = BuildJobQuery((MultiNode *) multiTree, masterDependedJobList);
multiPlan = CitusMakeNode(MultiPlan);
multiPlan->workerJob = workerJob;
multiPlan->masterQuery = masterQuery;
multiPlan->masterTableName = jobSchemaName->data;
return multiPlan;
}
/*
* BuildJobTree builds the physical job tree from the given logical plan tree.
* The function walks over the logical plan from the bottom up, finds boundaries
* for jobs, and creates the query structure for each job. The function also
* sets dependencies between jobs, and then returns the top level worker job.
*/
static Job *
BuildJobTree(MultiTreeRoot *multiTree)
{
/* start building the tree from the deepest left node */
MultiNode *leftMostNode = LeftMostNode(multiTree);
MultiNode *currentNode = leftMostNode;
MultiNode *parentNode = ParentNode(currentNode);
List *loopDependedJobList = NIL;
Job *topLevelJob = NULL;
while (parentNode != NULL)
{
CitusNodeTag currentNodeType = CitusNodeTag(currentNode);
CitusNodeTag parentNodeType = CitusNodeTag(parentNode);
BoundaryNodeJobType boundaryNodeJobType = JOB_INVALID_FIRST;
/* we first check if this node forms the boundary for a remote job */
if (currentNodeType == T_MultiJoin)
{
MultiJoin *joinNode = (MultiJoin *) currentNode;
if (joinNode->joinRuleType == SINGLE_PARTITION_JOIN ||
joinNode->joinRuleType == DUAL_PARTITION_JOIN)
{
boundaryNodeJobType = JOIN_MAP_MERGE_JOB;
}
}
else if (currentNodeType == T_MultiPartition &&
parentNodeType == T_MultiExtendedOp)
{
boundaryNodeJobType = SUBQUERY_MAP_MERGE_JOB;
}
else if (currentNodeType == T_MultiCollect &&
parentNodeType != T_MultiPartition)
{
boundaryNodeJobType = TOP_LEVEL_WORKER_JOB;
}
/*
* If this node is at the boundary for a repartition or top level worker
* job, we build the corresponding job(s) and set their dependencies.
*/
if (boundaryNodeJobType == JOIN_MAP_MERGE_JOB)
{
MultiJoin *joinNode = (MultiJoin *) currentNode;
MultiNode *leftChildNode = joinNode->binaryNode.leftChildNode;
MultiNode *rightChildNode = joinNode->binaryNode.rightChildNode;
PartitionType partitionType = PARTITION_INVALID_FIRST;
Oid baseRelationId = InvalidOid;
if (joinNode->joinRuleType == SINGLE_PARTITION_JOIN)
{
partitionType = RANGE_PARTITION_TYPE;
baseRelationId = RangePartitionJoinBaseRelationId(joinNode);
}
else if (joinNode->joinRuleType == DUAL_PARTITION_JOIN)
{
partitionType = HASH_PARTITION_TYPE;
}
if (CitusIsA(leftChildNode, MultiPartition))
{
MultiPartition *partitionNode = (MultiPartition *) leftChildNode;
MultiNode *queryNode = GrandChildNode((MultiUnaryNode *) partitionNode);
Var *partitionKey = partitionNode->partitionColumn;
/* build query and partition job */
List *dependedJobList = list_copy(loopDependedJobList);
Query *jobQuery = BuildJobQuery(queryNode, dependedJobList);
MapMergeJob *mapMergeJob = BuildMapMergeJob(jobQuery, dependedJobList,
partitionKey, partitionType,
baseRelationId,
JOIN_MAP_MERGE_JOB);
/* reset depended job list */
loopDependedJobList = NIL;
loopDependedJobList = list_make1(mapMergeJob);
}
if (CitusIsA(rightChildNode, MultiPartition))
{
MultiPartition *partitionNode = (MultiPartition *) rightChildNode;
MultiNode *queryNode = GrandChildNode((MultiUnaryNode *) partitionNode);
Var *partitionKey = partitionNode->partitionColumn;
/*
* The right query and right partition job do not depend on any
* jobs since our logical plan tree is left deep.
*/
Query *jobQuery = BuildJobQuery(queryNode, NIL);
MapMergeJob *mapMergeJob = BuildMapMergeJob(jobQuery, NIL,
partitionKey, partitionType,
baseRelationId,
JOIN_MAP_MERGE_JOB);
/* append to the depended job list for on-going dependencies */
loopDependedJobList = lappend(loopDependedJobList, mapMergeJob);
}
}
else if (boundaryNodeJobType == SUBQUERY_MAP_MERGE_JOB)
{
MultiPartition *partitionNode = (MultiPartition *) currentNode;
MultiNode *queryNode = GrandChildNode((MultiUnaryNode *) partitionNode);
Var *partitionKey = partitionNode->partitionColumn;
/* build query and partition job */
List *dependedJobList = list_copy(loopDependedJobList);
Query *jobQuery = BuildJobQuery(queryNode, dependedJobList);
MapMergeJob *mapMergeJob = BuildMapMergeJob(jobQuery, dependedJobList,
partitionKey, HASH_PARTITION_TYPE,
InvalidOid,
SUBQUERY_MAP_MERGE_JOB);
Query *reduceQuery = BuildReduceQuery((MultiExtendedOp *) parentNode,
list_make1(mapMergeJob));
mapMergeJob->reduceQuery = reduceQuery;
/* reset depended job list */
loopDependedJobList = NIL;
loopDependedJobList = list_make1(mapMergeJob);
}
else if (boundaryNodeJobType == TOP_LEVEL_WORKER_JOB)
{
MultiNode *childNode = ChildNode((MultiUnaryNode *) currentNode);
List *dependedJobList = list_copy(loopDependedJobList);
bool subqueryPushdown = false;
List *subqueryMultiTableList = SubqueryMultiTableList(childNode);
int subqueryCount = list_length(subqueryMultiTableList);
if (subqueryCount > 0)
{
subqueryPushdown = true;
}
/*
* Build top level query. If subquery pushdown is set, we use
* sligthly different version of BuildJobQuery(). They are similar
* but we don't need some parts of BuildJobQuery() for subquery
* pushdown such as updating column attributes etc.
*/
if (subqueryPushdown)
{
Query *topLevelQuery = BuildSubqueryJobQuery(childNode);
topLevelJob = BuildJob(topLevelQuery, dependedJobList);
topLevelJob->subqueryPushdown = true;
}
else
{
Query *topLevelQuery = BuildJobQuery(childNode, dependedJobList);
topLevelJob = BuildJob(topLevelQuery, dependedJobList);
}
}
/* walk up the tree */
currentNode = parentNode;
parentNode = ParentNode(currentNode);
}
return topLevelJob;
}
/*
* LeftMostNode finds the deepest left node in the left-deep logical plan tree.
* We build the physical plan by traversing the logical plan from the bottom up;
* and this function helps us find the bottom of the logical tree.
*/
static MultiNode *
LeftMostNode(MultiTreeRoot *multiTree)
{
MultiNode *currentNode = (MultiNode *) multiTree;
MultiNode *leftChildNode = ChildNode((MultiUnaryNode *) multiTree);
while (leftChildNode != NULL)
{
currentNode = leftChildNode;
if (UnaryOperator(currentNode))
{
leftChildNode = ChildNode((MultiUnaryNode *) currentNode);
}
else if (BinaryOperator(currentNode))
{
MultiBinaryNode *binaryNode = (MultiBinaryNode *) currentNode;
leftChildNode = binaryNode->leftChildNode;
}
}
return currentNode;
}
/*
* RangePartitionJoinBaseRelationId finds partition node from join node, and
* returns base relation id of this node. Note that this function assumes that
* given join node is range partition join type.
*/
static Oid
RangePartitionJoinBaseRelationId(MultiJoin *joinNode)
{
MultiPartition *partitionNode = NULL;
MultiTable *baseTable = NULL;
Index baseTableId = 0;
Oid baseRelationId = InvalidOid;
MultiNode *leftChildNode = joinNode->binaryNode.leftChildNode;
MultiNode *rightChildNode = joinNode->binaryNode.rightChildNode;
if (CitusIsA(leftChildNode, MultiPartition))
{
partitionNode = (MultiPartition *) leftChildNode;
}
else if (CitusIsA(rightChildNode, MultiPartition))
{
partitionNode = (MultiPartition *) rightChildNode;
}
baseTableId = partitionNode->splitPointTableId;
baseTable = FindTableNode((MultiNode *) joinNode, baseTableId);
baseRelationId = baseTable->relationId;
return baseRelationId;
}
/*
* FindTableNode walks over the given logical plan tree, and returns the table
* node that corresponds to the given range tableId.
*/
static MultiTable *
FindTableNode(MultiNode *multiNode, int rangeTableId)
{
MultiTable *foundTableNode = NULL;
List *tableNodeList = FindNodesOfType(multiNode, T_MultiTable);
ListCell *tableNodeCell = NULL;
foreach(tableNodeCell, tableNodeList)
{
MultiTable *tableNode = (MultiTable *) lfirst(tableNodeCell);
if (tableNode->rangeTableId == rangeTableId)
{
foundTableNode = tableNode;
break;
}
}
Assert(foundTableNode != NULL);
return foundTableNode;
}
/*
* BuildJobQuery traverses the given logical plan tree, determines the job that
* corresponds to this part of the tree, and builds the query structure for that
* particular job. The function assumes that jobs, this particular job depends on,
* have already been built, as their output is needed to build the query.
*/
static Query *
BuildJobQuery(MultiNode *multiNode, List *dependedJobList)
{
Query *jobQuery = NULL;
MultiNode *parentNode = NULL;
bool updateColumnAttributes = false;
List *rangeTableList = NIL;
List *targetList = NIL;
List *extendedOpNodeList = NIL;
List *sortClauseList = NIL;
List *groupClauseList = NIL;
List *selectClauseList = NIL;
List *columnList = NIL;
Node *limitCount = NULL;
Node *limitOffset = NULL;
ListCell *columnCell = NULL;
FromExpr *joinTree = NULL;
Node *joinRoot = NULL;
/* we start building jobs from below the collect node */
Assert(!CitusIsA(multiNode, MultiCollect));
/*
* First check if we are building a master/worker query. If we are building
* a worker query, we update the column attributes for target entries, select
* and join columns. Because if underlying query includes repartition joins,
* then we create multiple queries from a join. In this case, range table lists
* and column lists are subject to change.
*
* Note that we don't do this for master queries, as column attributes for
* master target entries are already set during the master/worker split.
*/
parentNode = ParentNode(multiNode);
if (parentNode != NULL)
{
updateColumnAttributes = true;
}
/*
* If we are building this query on a repartitioned subquery job then we
* don't need to update column attributes.
*/
if (dependedJobList != NIL)
{
Job *job = (Job *) linitial(dependedJobList);
if (CitusIsA(job, MapMergeJob))
{
MapMergeJob *mapMergeJob = (MapMergeJob *) job;
if (mapMergeJob->reduceQuery)
{
updateColumnAttributes = false;
}
}
}
/*
* If we have an extended operator, then we copy the operator's target list.
* Otherwise, we use the target list based on the MultiProject node at this
* level in the query tree.
*/
extendedOpNodeList = FindNodesOfType(multiNode, T_MultiExtendedOp);
if (extendedOpNodeList != NIL)
{
MultiExtendedOp *extendedOp = (MultiExtendedOp *) linitial(extendedOpNodeList);
targetList = copyObject(extendedOp->targetList);
}
else
{
targetList = QueryTargetList(multiNode);
}
/* build the join tree and the range table list */
rangeTableList = BaseRangeTableList(multiNode);
joinRoot = QueryJoinTree(multiNode, dependedJobList, &rangeTableList);
/* update the column attributes for target entries */
if (updateColumnAttributes)
{
ListCell *columnCell = NULL;
List *columnList = pull_var_clause_default((Node *) targetList);
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
UpdateColumnAttributes(column, rangeTableList, dependedJobList);
}
}
/* extract limit count/offset and sort clauses */
if (extendedOpNodeList != NIL)
{
MultiExtendedOp *extendedOp = (MultiExtendedOp *) linitial(extendedOpNodeList);
limitCount = extendedOp->limitCount;
limitOffset = extendedOp->limitOffset;
sortClauseList = extendedOp->sortClauseList;
}
/* build group clauses */
groupClauseList = QueryGroupClauseList(multiNode);
/* build the where clause list using select predicates */
selectClauseList = QuerySelectClauseList(multiNode);
/* set correct column attributes for select columns */
if (updateColumnAttributes)
{
columnCell = NULL;
columnList = pull_var_clause_default((Node *) selectClauseList);
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
UpdateColumnAttributes(column, rangeTableList, dependedJobList);
}
}
/*
* Build the From/Where construct. We keep the where-clause list implicitly
* AND'd, since both partition and join pruning depends on the clauses being
* expressed as a list.
*/
joinTree = makeNode(FromExpr);
joinTree->quals = (Node *) list_copy(selectClauseList);
joinTree->fromlist = list_make1(joinRoot);
/* build the query structure for this job */
jobQuery = makeNode(Query);
jobQuery->commandType = CMD_SELECT;
jobQuery->querySource = QSRC_ORIGINAL;
jobQuery->canSetTag = true;
jobQuery->rtable = rangeTableList;
jobQuery->targetList = targetList;
jobQuery->jointree = joinTree;
jobQuery->sortClause = sortClauseList;
jobQuery->groupClause = groupClauseList;
jobQuery->limitOffset = limitOffset;
jobQuery->limitCount = limitCount;
jobQuery->hasAggs = contain_agg_clause((Node *) targetList);
return jobQuery;
}
/*
* BuildReduceQuery traverses the given logical plan tree, determines the job that
* corresponds to this part of the tree, and builds the query structure for that
* particular job. The function assumes that jobs this particular job depends on
* have already been built, as their output is needed to build the query.
*/
static Query *
BuildReduceQuery(MultiExtendedOp *extendedOpNode, List *dependedJobList)
{
Query *reduceQuery = NULL;
MultiNode *multiNode = (MultiNode *) extendedOpNode;
List *derivedRangeTableList = NIL;
List *targetList = NIL;
List *whereClauseList = NIL;
List *selectClauseList = NIL;
List *joinClauseList = NIL;
List *columnList = NIL;
ListCell *columnCell = NULL;
FromExpr *joinTree = NULL;
List *columnNameList = NIL;
RangeTblEntry *rangeTableEntry = NULL;
Job *dependedJob = linitial(dependedJobList);
List *dependedTargetList = dependedJob->jobQuery->targetList;
uint32 columnCount = (uint32) list_length(dependedTargetList);
uint32 columnIndex = 0;
for (columnIndex = 0; columnIndex < columnCount; columnIndex++)
{
Value *columnValue = NULL;
StringInfo columnNameString = makeStringInfo();
appendStringInfo(columnNameString, MERGE_COLUMN_FORMAT, columnIndex);
columnValue = makeString(columnNameString->data);
columnNameList = lappend(columnNameList, columnValue);
}
/* create a derived range table for the subtree below the collect */
rangeTableEntry = DerivedRangeTableEntry(multiNode, columnNameList,
OutputTableIdList(multiNode));
rangeTableEntry->eref->colnames = columnNameList;
ModifyRangeTblExtraData(rangeTableEntry, CITUS_RTE_SHARD, NULL, NULL, NULL);
derivedRangeTableList = lappend(derivedRangeTableList, rangeTableEntry);
targetList = copyObject(extendedOpNode->targetList);
columnList = pull_var_clause_default((Node *) targetList);
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
Index originalTableId = column->varnoold;
/* find the new table identifier */
Index newTableId = NewTableId(originalTableId, derivedRangeTableList);
column->varno = newTableId;
}
/* build the where clause list using select and join predicates */
selectClauseList = QuerySelectClauseList((MultiNode *) extendedOpNode);
joinClauseList = QueryJoinClauseList((MultiNode *) extendedOpNode);
whereClauseList = list_concat(selectClauseList, joinClauseList);
/*
* Build the From/Where construct. We keep the where-clause list implicitly
* AND'd, since both partition and join pruning depends on the clauses being
* expressed as a list.
*/
joinTree = makeNode(FromExpr);
joinTree->quals = (Node *) whereClauseList;
joinTree->fromlist = QueryFromList(derivedRangeTableList);
/* build the query structure for this job */
reduceQuery = makeNode(Query);
reduceQuery->commandType = CMD_SELECT;
reduceQuery->querySource = QSRC_ORIGINAL;
reduceQuery->canSetTag = true;
reduceQuery->rtable = derivedRangeTableList;
reduceQuery->targetList = targetList;
reduceQuery->jointree = joinTree;
reduceQuery->sortClause = extendedOpNode->sortClauseList;
reduceQuery->groupClause = extendedOpNode->groupClauseList;
reduceQuery->limitOffset = extendedOpNode->limitOffset;
reduceQuery->limitCount = extendedOpNode->limitCount;
reduceQuery->hasAggs = contain_agg_clause((Node *) targetList);
return reduceQuery;
}
/*
* BaseRangeTableList returns the list of range table entries for base tables in
* the query. These base tables stand in contrast to derived tables generated by
* repartition jobs. Note that this function only considers base tables relevant
* to the current query, and does not visit nodes under the collect node.
*/
static List *
BaseRangeTableList(MultiNode *multiNode)
{
List *baseRangeTableList = NIL;
List *pendingNodeList = list_make1(multiNode);
while (pendingNodeList != NIL)
{
MultiNode *multiNode = (MultiNode *) linitial(pendingNodeList);
CitusNodeTag nodeType = CitusNodeTag(multiNode);
pendingNodeList = list_delete_first(pendingNodeList);
if (nodeType == T_MultiTable)
{
/*
* We represent subqueries as MultiTables, and so for base table
* entries we skip the subquery ones.
*/
MultiTable *multiTable = (MultiTable *) multiNode;
if (multiTable->relationId != SUBQUERY_RELATION_ID &&
multiTable->relationId != HEAP_ANALYTICS_SUBQUERY_RELATION_ID)
{
RangeTblEntry *rangeTableEntry = makeNode(RangeTblEntry);
rangeTableEntry->inFromCl = true;
rangeTableEntry->eref = multiTable->referenceNames;
rangeTableEntry->alias = multiTable->alias;
rangeTableEntry->relid = multiTable->relationId;
SetRangeTblExtraData(rangeTableEntry, CITUS_RTE_RELATION, NULL, NULL,
list_make1_int(multiTable->rangeTableId));
baseRangeTableList = lappend(baseRangeTableList, rangeTableEntry);
}
}
/* do not visit nodes that belong to remote queries */
if (nodeType != T_MultiCollect)
{
List *childNodeList = ChildNodeList(multiNode);
pendingNodeList = list_concat(pendingNodeList, childNodeList);
}
}
return baseRangeTableList;
}
/*
* DerivedRangeTableEntry builds a range table entry for the derived table. This
* derived table either represents the output of a repartition job; or the data
* on worker nodes in case of the master node query.
*/
static RangeTblEntry *
DerivedRangeTableEntry(MultiNode *multiNode, List *columnList, List *tableIdList)
{
RangeTblEntry *rangeTableEntry = makeNode(RangeTblEntry);
rangeTableEntry->inFromCl = true;
rangeTableEntry->eref = makeNode(Alias);
rangeTableEntry->eref->colnames = columnList;
SetRangeTblExtraData(rangeTableEntry, CITUS_RTE_REMOTE_QUERY, NULL, NULL,
tableIdList);
return rangeTableEntry;
}
/*
* DerivedColumnNameList builds a column name list for derived (intermediate)
* tables. These column names are then used when building the create stament
* query string for derived tables.
*/
static List *
DerivedColumnNameList(uint32 columnCount, uint64 generatingJobId)
{
List *columnNameList = NIL;
uint32 columnIndex = 0;
for (columnIndex = 0; columnIndex < columnCount; columnIndex++)
{
StringInfo columnName = makeStringInfo();
Value *columnValue = NULL;
appendStringInfo(columnName, "intermediate_column_");
appendStringInfo(columnName, UINT64_FORMAT "_", generatingJobId);
appendStringInfo(columnName, "%u", columnIndex);
columnValue = makeString(columnName->data);
columnNameList = lappend(columnNameList, columnValue);
}
return columnNameList;
}
/*
* QueryTargetList returns the target entry list for the projected columns
* needed to evaluate the operators above the given multiNode. To do this,
* the function retrieves a list of all MultiProject nodes below the given
* node and picks the columns from the top-most MultiProject node, as this
* will be the minimal list of columns needed. Note that this function relies
* on a pre-order traversal of the operator tree by the function FindNodesOfType.
*/
static List *
QueryTargetList(MultiNode *multiNode)
{
MultiProject *topProjectNode = NULL;
List *columnList = NIL;
List *queryTargetList = NIL;
List *projectNodeList = FindNodesOfType(multiNode, T_MultiProject);
Assert(list_length(projectNodeList) > 0);
topProjectNode = (MultiProject *) linitial(projectNodeList);
columnList = topProjectNode->columnList;
queryTargetList = TargetEntryList(columnList);
Assert(queryTargetList != NIL);
return queryTargetList;
}
/*
* TargetEntryList creates a target entry for each expression in the given list,
* and returns the newly created target entries in a list.
*/
static List *
TargetEntryList(List *expressionList)
{
List *targetEntryList = NIL;
ListCell *expressionCell = NULL;
foreach(expressionCell, expressionList)
{
Expr *expression = (Expr *) lfirst(expressionCell);
TargetEntry *targetEntry = makeTargetEntry(expression,
list_length(targetEntryList) + 1,
NULL, false);
targetEntryList = lappend(targetEntryList, targetEntry);
}
return targetEntryList;
}
/*
* QueryGroupClauseList extracts the group clause list from the logical plan. If
* no grouping clauses exist, the function returns an empty list.
*/
static List *
QueryGroupClauseList(MultiNode *multiNode)
{
List *groupClauseList = NIL;
List *pendingNodeList = list_make1(multiNode);
while (pendingNodeList != NIL)
{
MultiNode *multiNode = (MultiNode *) linitial(pendingNodeList);
CitusNodeTag nodeType = CitusNodeTag(multiNode);
pendingNodeList = list_delete_first(pendingNodeList);
/* extract the group clause list from the extended operator */
if (nodeType == T_MultiExtendedOp)
{
MultiExtendedOp *extendedOpNode = (MultiExtendedOp *) multiNode;
groupClauseList = extendedOpNode->groupClauseList;
}
/* add children only if this node isn't a multi collect and multi table */
if (nodeType != T_MultiCollect && nodeType != T_MultiTable)
{
List *childNodeList = ChildNodeList(multiNode);
pendingNodeList = list_concat(pendingNodeList, childNodeList);
}
}
return groupClauseList;
}
/*
* QuerySelectClauseList traverses the given logical plan tree, and extracts all
* select clauses from the select nodes. Note that this function does not walk
* below a collect node; the clauses below the collect node apply to a remote
* query, and they would have been captured by the remote job we depend upon.
*/
static List *
QuerySelectClauseList(MultiNode *multiNode)
{
List *selectClauseList = NIL;
List *pendingNodeList = list_make1(multiNode);
while (pendingNodeList != NIL)
{
MultiNode *multiNode = (MultiNode *) linitial(pendingNodeList);
CitusNodeTag nodeType = CitusNodeTag(multiNode);
pendingNodeList = list_delete_first(pendingNodeList);
/* extract select clauses from the multi select node */
if (nodeType == T_MultiSelect)
{
MultiSelect *selectNode = (MultiSelect *) multiNode;
List *clauseList = copyObject(selectNode->selectClauseList);
selectClauseList = list_concat(selectClauseList, clauseList);
}
/* add children only if this node isn't a multi collect */
if (nodeType != T_MultiCollect)
{
List *childNodeList = ChildNodeList(multiNode);
pendingNodeList = list_concat(pendingNodeList, childNodeList);
}
}
return selectClauseList;
}
/*
* QueryJoinClauseList traverses the given logical plan tree, and extracts all
* join clauses from the join nodes. Note that this function does not walk below
* a collect node; the clauses below the collect node apply to another query,
* and they would have been captured by the remote job we depend upon.
*/
static List *
QueryJoinClauseList(MultiNode *multiNode)
{
List *joinClauseList = NIL;
List *pendingNodeList = list_make1(multiNode);
while (pendingNodeList != NIL)
{
MultiNode *multiNode = (MultiNode *) linitial(pendingNodeList);
CitusNodeTag nodeType = CitusNodeTag(multiNode);
pendingNodeList = list_delete_first(pendingNodeList);
/* extract join clauses from the multi join node */
if (nodeType == T_MultiJoin)
{
MultiJoin *joinNode = (MultiJoin *) multiNode;
List *clauseList = copyObject(joinNode->joinClauseList);
joinClauseList = list_concat(joinClauseList, clauseList);
}
/* add this node's children only if the node isn't a multi collect */
if (nodeType != T_MultiCollect)
{
List *childNodeList = ChildNodeList(multiNode);
pendingNodeList = list_concat(pendingNodeList, childNodeList);
}
}
return joinClauseList;
}
/*
* Create a tree of JoinExpr and RangeTblRef nodes for the job query from
* a given multiNode. If the tree contains MultiCollect or MultiJoin nodes,
* add corresponding entries to the range table list. We need to construct
* the entries at the same time as the tree to know the appropriate rtindex.
*/
static Node *
QueryJoinTree(MultiNode *multiNode, List *dependedJobList, List **rangeTableList)
{
CitusNodeTag nodeType = CitusNodeTag(multiNode);
switch (nodeType)
{
case T_MultiJoin:
{
MultiJoin *joinNode = (MultiJoin *) multiNode;
MultiBinaryNode *binaryNode = (MultiBinaryNode *) multiNode;
List *columnList = NIL;
ListCell *columnCell = NULL;
RangeTblEntry *rangeTableEntry = NULL;
JoinExpr *joinExpr = makeNode(JoinExpr);
joinExpr->jointype = joinNode->joinType;
joinExpr->isNatural = false;
joinExpr->larg = QueryJoinTree(binaryNode->leftChildNode, dependedJobList,
rangeTableList);
joinExpr->rarg = QueryJoinTree(binaryNode->rightChildNode, dependedJobList,
rangeTableList);
joinExpr->usingClause = NIL;
joinExpr->alias = NULL;
joinExpr->rtindex = list_length(*rangeTableList) + 1;
/*
* PostgreSQL's optimizer may mark left joins as anti-joins, when there
* is an right-hand-join-key-is-null restriction, but there is no logic
* in ruleutils to deparse anti-joins, so we cannot construct a task
* query containing anti-joins. We therefore translate anti-joins back
* into left-joins. At some point, we may also want to use different
* join pruning logic for anti-joins.
*
* This approach would not work for anti-joins introduced via NOT EXISTS
* sublinks, but currently such queries are prevented by error checks in
* the logical planner.
*/
if (joinExpr->jointype == JOIN_ANTI)
{
joinExpr->jointype = JOIN_LEFT;
}
rangeTableEntry = JoinRangeTableEntry(joinExpr, dependedJobList,
*rangeTableList);
*rangeTableList = lappend(*rangeTableList, rangeTableEntry);
/* fix the column attributes in ON (...) clauses */
columnList = pull_var_clause_default((Node *) joinNode->joinClauseList);
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
UpdateColumnAttributes(column, *rangeTableList, dependedJobList);
/* adjust our column old attributes for partition pruning to work */
column->varnoold = column->varno;
column->varoattno = column->varattno;
}
/* make AND clauses explicit after fixing them */
joinExpr->quals = (Node *) make_ands_explicit(joinNode->joinClauseList);
return (Node *) joinExpr;
}
case T_MultiTable:
{
MultiTable *rangeTableNode = (MultiTable *) multiNode;
MultiUnaryNode *unaryNode = (MultiUnaryNode *) multiNode;
if (unaryNode->childNode != NULL)
{
/* MultiTable is actually a subquery, return the query tree below */
Node *childNode = QueryJoinTree(unaryNode->childNode, dependedJobList,
rangeTableList);
return childNode;
}
else
{
RangeTblRef *rangeTableRef = makeNode(RangeTblRef);
uint32 rangeTableId = rangeTableNode->rangeTableId;
rangeTableRef->rtindex = NewTableId(rangeTableId, *rangeTableList);
return (Node *) rangeTableRef;
}
}
case T_MultiCollect:
{
List *tableIdList = OutputTableIdList(multiNode);
Job *dependedJob = JobForTableIdList(dependedJobList, tableIdList);
List *dependedTargetList = dependedJob->jobQuery->targetList;
/* compute column names for the derived table */
uint32 columnCount = (uint32) list_length(dependedTargetList);
List *columnNameList = DerivedColumnNameList(columnCount, dependedJob->jobId);
RangeTblEntry *rangeTableEntry = DerivedRangeTableEntry(multiNode,
columnNameList,
tableIdList);
RangeTblRef *rangeTableRef = makeNode(RangeTblRef);
rangeTableRef->rtindex = list_length(*rangeTableList) + 1;
*rangeTableList = lappend(*rangeTableList, rangeTableEntry);
return (Node *) rangeTableRef;
}
case T_MultiCartesianProduct:
{
MultiBinaryNode *binaryNode = (MultiBinaryNode *) multiNode;
RangeTblEntry *rangeTableEntry = NULL;
JoinExpr *joinExpr = makeNode(JoinExpr);
joinExpr->jointype = JOIN_INNER;
joinExpr->isNatural = false;
joinExpr->larg = QueryJoinTree(binaryNode->leftChildNode, dependedJobList,
rangeTableList);
joinExpr->rarg = QueryJoinTree(binaryNode->rightChildNode, dependedJobList,
rangeTableList);
joinExpr->usingClause = NIL;
joinExpr->alias = NULL;
joinExpr->quals = NULL;
joinExpr->rtindex = list_length(*rangeTableList) + 1;
rangeTableEntry = JoinRangeTableEntry(joinExpr, dependedJobList,
*rangeTableList);
*rangeTableList = lappend(*rangeTableList, rangeTableEntry);
return (Node *) joinExpr;
}
case T_MultiTreeRoot:
case T_MultiSelect:
case T_MultiProject:
case T_MultiExtendedOp:
case T_MultiPartition:
{
MultiUnaryNode *unaryNode = (MultiUnaryNode *) multiNode;
Node *childNode = NULL;
Assert(UnaryOperator(multiNode));
childNode = QueryJoinTree(unaryNode->childNode, dependedJobList,
rangeTableList);
return childNode;
}
default:
{
ereport(ERROR, (errmsg("unrecognized multi-node type: %d", nodeType)));
}
}
}
/*
* JoinRangeTableEntry builds a range table entry for a fully initialized JoinExpr node.
* The column names and vars are determined using expandRTE, analogous to
* transformFromClauseItem.
*/
static RangeTblEntry *
JoinRangeTableEntry(JoinExpr *joinExpr, List *dependedJobList, List *rangeTableList)
{
RangeTblEntry *rangeTableEntry = makeNode(RangeTblEntry);
List *joinedColumnNames = NIL;
List *joinedColumnVars = NIL;
List *leftColumnNames = NIL;
List *leftColumnVars = NIL;
int leftRangeTableId = ExtractRangeTableId(joinExpr->larg);
RangeTblEntry *leftRTE = rt_fetch(leftRangeTableId, rangeTableList);
List *rightColumnNames = NIL;
List *rightColumnVars = NIL;
int rightRangeTableId = ExtractRangeTableId(joinExpr->rarg);
RangeTblEntry *rightRTE = rt_fetch(rightRangeTableId, rangeTableList);
rangeTableEntry->rtekind = RTE_JOIN;
rangeTableEntry->relid = InvalidOid;
rangeTableEntry->inFromCl = true;
rangeTableEntry->alias = joinExpr->alias;
rangeTableEntry->jointype = joinExpr->jointype;
rangeTableEntry->subquery = NULL;
rangeTableEntry->eref = makeAlias("unnamed_join", NIL);
ExtractColumns(leftRTE, leftRangeTableId, dependedJobList,
&leftColumnNames, &leftColumnVars);
ExtractColumns(rightRTE, rightRangeTableId, dependedJobList,
&rightColumnNames, &rightColumnVars);
joinedColumnNames = list_concat(joinedColumnNames, leftColumnNames);
joinedColumnVars = list_concat(joinedColumnVars, leftColumnVars);
joinedColumnNames = list_concat(joinedColumnNames, rightColumnNames);
joinedColumnVars = list_concat(joinedColumnVars, rightColumnVars);
rangeTableEntry->eref->colnames = joinedColumnNames;
rangeTableEntry->joinaliasvars = joinedColumnVars;
return rangeTableEntry;
}
/*
* ExtractRangeTableId gets the range table id from a node that could
* either be a JoinExpr or RangeTblRef.
*/
static int
ExtractRangeTableId(Node *node)
{
int rangeTableId = 0;
if (IsA(node, JoinExpr))
{
JoinExpr *joinExpr = (JoinExpr *) node;
rangeTableId = joinExpr->rtindex;
}
else if (IsA(node, RangeTblRef))
{
RangeTblRef *rangeTableRef = (RangeTblRef *) node;
rangeTableId = rangeTableRef->rtindex;
}
Assert(rangeTableId > 0);
return rangeTableId;
}
/*
* ExtractColumns gets a list of column names and vars for a given range
* table entry using expandRTE. Since the range table entries in a job
* query are mocked RTE_FUNCTION entries, it first translates the RTE's
* to a form that expandRTE can handle.
*/
static void
ExtractColumns(RangeTblEntry *rangeTableEntry, int rangeTableId, List *dependedJobList,
List **columnNames, List **columnVars)
{
RangeTblEntry *callingRTE = NULL;
CitusRTEKind rangeTableKind = GetRangeTblKind(rangeTableEntry);
if (rangeTableKind == CITUS_RTE_JOIN)
{
/*
* For joins, we can call expandRTE directly.
*/
callingRTE = rangeTableEntry;
}
else if (rangeTableKind == CITUS_RTE_RELATION)
{
/*
* For distributed tables, we construct a regular table RTE to call
* expandRTE, which will extract columns from the distributed table
* schema.
*/
callingRTE = makeNode(RangeTblEntry);
callingRTE->rtekind = RTE_RELATION;
callingRTE->eref = rangeTableEntry->eref;
callingRTE->relid = rangeTableEntry->relid;
}
else if (rangeTableKind == CITUS_RTE_REMOTE_QUERY)
{
Job *dependedJob = JobForRangeTable(dependedJobList, rangeTableEntry);
Query *jobQuery = dependedJob->jobQuery;
/*
* For re-partition jobs, we construct a subquery RTE to call expandRTE,
* which will extract the columns from the target list of the job query.
*/
callingRTE = makeNode(RangeTblEntry);
callingRTE->rtekind = RTE_SUBQUERY;
callingRTE->eref = rangeTableEntry->eref;
callingRTE->subquery = jobQuery;
}
else
{
ereport(ERROR, (errmsg("unsupported Citus RTE kind: %d", rangeTableKind)));
}
expandRTE(callingRTE, rangeTableId, 0, -1, false, columnNames, columnVars);
}
/*
* QueryFromList creates the from list construct that is used for building the
* query's join tree. The function creates the from list by making a range table
* reference for each entry in the given range table list.
*/
static List *
QueryFromList(List *rangeTableList)
{
List *fromList = NIL;
Index rangeTableIndex = 1;
int rangeTableCount = list_length(rangeTableList);
for (rangeTableIndex = 1; rangeTableIndex <= rangeTableCount; rangeTableIndex++)
{
RangeTblRef *rangeTableReference = makeNode(RangeTblRef);
rangeTableReference->rtindex = rangeTableIndex;
fromList = lappend(fromList, rangeTableReference);
}
return fromList;
}
/*
* BuildSubqueryJobQuery traverses the given logical plan tree, finds MultiTable
* which represents the subquery. It builds the query structure by adding this
* subquery as it is to range table list of the query.
*
* Such as if user runs a query like this;
*
* SELECT avg(id) FROM (
* SELECT ... FROM ()
* )
*
* then this function will build this worker query as keeping subquery as it is;
*
* SELECT sum(id), count(id) FROM (
* SELECT ... FROM ()
* )
*/
static Query *
BuildSubqueryJobQuery(MultiNode *multiNode)
{
Query *jobQuery = NULL;
Query *subquery = NULL;
MultiTable *multiTable = NULL;
RangeTblEntry *rangeTableEntry = NULL;
List *subqueryMultiTableList = NIL;
List *rangeTableList = NIL;
List *targetList = NIL;
List *extendedOpNodeList = NIL;
List *sortClauseList = NIL;
List *groupClauseList = NIL;
List *whereClauseList = NIL;
Node *limitCount = NULL;
Node *limitOffset = NULL;
FromExpr *joinTree = NULL;
/* we start building jobs from below the collect node */
Assert(!CitusIsA(multiNode, MultiCollect));
subqueryMultiTableList = SubqueryMultiTableList(multiNode);
Assert(list_length(subqueryMultiTableList) == 1);
multiTable = (MultiTable *) linitial(subqueryMultiTableList);
subquery = multiTable->subquery;
/* build subquery range table list */
rangeTableEntry = makeNode(RangeTblEntry);
rangeTableEntry->rtekind = RTE_SUBQUERY;
rangeTableEntry->inFromCl = true;
rangeTableEntry->eref = multiTable->referenceNames;
rangeTableEntry->alias = multiTable->alias;
rangeTableEntry->subquery = subquery;
rangeTableList = list_make1(rangeTableEntry);
/*
* If we have an extended operator, then we copy the operator's target list.
* Otherwise, we use the target list based on the MultiProject node at this
* level in the query tree.
*/
extendedOpNodeList = FindNodesOfType(multiNode, T_MultiExtendedOp);
if (extendedOpNodeList != NIL)
{
MultiExtendedOp *extendedOp = (MultiExtendedOp *) linitial(extendedOpNodeList);
targetList = copyObject(extendedOp->targetList);
}
else
{
targetList = QueryTargetList(multiNode);
}
/* extract limit count/offset and sort clauses */
if (extendedOpNodeList != NIL)
{
MultiExtendedOp *extendedOp = (MultiExtendedOp *) linitial(extendedOpNodeList);
limitCount = extendedOp->limitCount;
limitOffset = extendedOp->limitOffset;
sortClauseList = extendedOp->sortClauseList;
}
/* build group clauses */
groupClauseList = QueryGroupClauseList(multiNode);
/* build the where clause list using select predicates */
whereClauseList = QuerySelectClauseList(multiNode);
/*
* Build the From/Where construct. We keep the where-clause list implicitly
* AND'd, since both partition and join pruning depends on the clauses being
* expressed as a list.
*/
joinTree = makeNode(FromExpr);
joinTree->quals = (Node *) whereClauseList;
joinTree->fromlist = QueryFromList(rangeTableList);
/* build the query structure for this job */
jobQuery = makeNode(Query);
jobQuery->commandType = CMD_SELECT;
jobQuery->querySource = QSRC_ORIGINAL;
jobQuery->canSetTag = true;
jobQuery->rtable = rangeTableList;
jobQuery->targetList = targetList;
jobQuery->jointree = joinTree;
jobQuery->sortClause = sortClauseList;
jobQuery->groupClause = groupClauseList;
jobQuery->limitOffset = limitOffset;
jobQuery->limitCount = limitCount;
jobQuery->hasAggs = contain_agg_clause((Node *) targetList);
return jobQuery;
}
/*
* UpdateColumnAttributes updates the column's range table reference (varno) and
* column attribute number for the range table (varattno). The function uses the
* newly built range table list to update the given column's attributes.
*/
static void
UpdateColumnAttributes(Var *column, List *rangeTableList, List *dependedJobList)
{
Index originalTableId = column->varnoold;
AttrNumber originalColumnId = column->varoattno;
/* find the new table identifier */
Index newTableId = NewTableId(originalTableId, rangeTableList);
AttrNumber newColumnId = originalColumnId;
/* if this is a derived table, find the new column identifier */
RangeTblEntry *newRangeTableEntry = rt_fetch(newTableId, rangeTableList);
if (GetRangeTblKind(newRangeTableEntry) == CITUS_RTE_REMOTE_QUERY)
{
newColumnId = NewColumnId(originalTableId, originalColumnId,
newRangeTableEntry, dependedJobList);
}
column->varno = newTableId;
column->varattno = newColumnId;
}
/*
* NewTableId determines the new tableId for the query that is currently being
* built. In this query, the original tableId represents the order of the table
* in the initial parse tree. When queries involve repartitioning, we re-order
* tables; and the new tableId corresponds to this new table order.
*/
static Index
NewTableId(Index originalTableId, List *rangeTableList)
{
Index newTableId = 0;
Index rangeTableIndex = 1;
ListCell *rangeTableCell = NULL;
foreach(rangeTableCell, rangeTableList)
{
RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
List *originalTableIdList = NIL;
bool listMember = false;
ExtractRangeTblExtraData(rangeTableEntry, NULL, NULL, NULL, &originalTableIdList);
listMember = list_member_int(originalTableIdList, originalTableId);
if (listMember)
{
newTableId = rangeTableIndex;
break;
}
rangeTableIndex++;
}
return newTableId;
}
/*
* NewColumnId determines the new columnId for the query that is currently being
* built. In this query, the original columnId corresponds to the column in base
* tables. When the current query is a partition job and generates intermediate
* tables, the columns have a different order and the new columnId corresponds
* to this order. Please note that this function assumes columnIds for depended
* jobs have already been updated.
*/
static AttrNumber
NewColumnId(Index originalTableId, AttrNumber originalColumnId,
RangeTblEntry *newRangeTableEntry, List *dependedJobList)
{
AttrNumber newColumnId = 1;
AttrNumber columnIndex = 1;
Job *dependedJob = JobForRangeTable(dependedJobList, newRangeTableEntry);
List *targetEntryList = dependedJob->jobQuery->targetList;
ListCell *targetEntryCell = NULL;
foreach(targetEntryCell, targetEntryList)
{
TargetEntry *targetEntry = (TargetEntry *) lfirst(targetEntryCell);
Expr *expression = targetEntry->expr;
Var *column = (Var *) expression;
Assert(IsA(expression, Var));
/*
* Check against the *old* values for this column, as the new values
* would have been updated already.
*/
if (column->varnoold == originalTableId &&
column->varoattno == originalColumnId)
{
newColumnId = columnIndex;
break;
}
columnIndex++;
}
return newColumnId;
}
/*
* JobForRangeTable returns the job that corresponds to the given range table
* entry. The function walks over jobs in the given job list, and compares each
* job's table list against the given range table entry's table list. When two
* table lists match, the function returns the matching job. Note that we call
* this function in practice when we need to determine which one of the jobs we
* depend upon corresponds to given range table entry.
*/
static Job *
JobForRangeTable(List *jobList, RangeTblEntry *rangeTableEntry)
{
Job *searchedJob = NULL;
List *searchedTableIdList = NIL;
CitusRTEKind rangeTableKind;
ExtractRangeTblExtraData(rangeTableEntry, &rangeTableKind, NULL, NULL,
&searchedTableIdList);
Assert(rangeTableKind == CITUS_RTE_REMOTE_QUERY);
searchedJob = JobForTableIdList(jobList, searchedTableIdList);
return searchedJob;
}
/*
* JobForTableIdList returns the job that corresponds to the given
* tableIdList. The function walks over jobs in the given job list, and
* compares each job's table list against the given table list. When the
* two table lists match, the function returns the matching job.
*/
static Job *
JobForTableIdList(List *jobList, List *searchedTableIdList)
{
Job *searchedJob = NULL;
ListCell *jobCell = NULL;
foreach(jobCell, jobList)
{
Job *job = (Job *) lfirst(jobCell);
List *jobRangeTableList = job->jobQuery->rtable;
List *jobTableIdList = NIL;
ListCell *jobRangeTableCell = NULL;
List *lhsDiff = NIL;
List *rhsDiff = NIL;
foreach(jobRangeTableCell, jobRangeTableList)
{
RangeTblEntry *jobRangeTable = (RangeTblEntry *) lfirst(jobRangeTableCell);
List *tableIdList = NIL;
ExtractRangeTblExtraData(jobRangeTable, NULL, NULL, NULL, &tableIdList);
/* copy the list since list_concat is destructive */
tableIdList = list_copy(tableIdList);
jobTableIdList = list_concat(jobTableIdList, tableIdList);
}
/*
* Check if the searched range table's tableIds and the current job's
* tableIds are the same.
*/
lhsDiff = list_difference_int(jobTableIdList, searchedTableIdList);
rhsDiff = list_difference_int(searchedTableIdList, jobTableIdList);
if (lhsDiff == NIL && rhsDiff == NIL)
{
searchedJob = job;
break;
}
}
Assert(searchedJob != NULL);
return searchedJob;
}
/* Returns the list of children for the given multi node. */
static List *
ChildNodeList(MultiNode *multiNode)
{
List *childNodeList = NIL;
bool unaryNode = UnaryOperator(multiNode);
bool binaryNode = BinaryOperator(multiNode);
/* relation table nodes don't have any children */
if (CitusIsA(multiNode, MultiTable))
{
MultiTable *multiTable = (MultiTable *) multiNode;
if (multiTable->relationId != SUBQUERY_RELATION_ID)
{
return NIL;
}
}
if (unaryNode)
{
MultiUnaryNode *unaryNode = (MultiUnaryNode *) multiNode;
childNodeList = list_make1(unaryNode->childNode);
}
else if (binaryNode)
{
MultiBinaryNode *binaryNode = (MultiBinaryNode *) multiNode;
childNodeList = list_make2(binaryNode->leftChildNode,
binaryNode->rightChildNode);
}
return childNodeList;
}
/*
* UniqueJobId allocates and returns a unique jobId for the job to be executed.
* This allocation occurs both in shared memory and in write ahead logs; writing
* to logs avoids the risk of having jobId collisions.
*
* Please note that the jobId sequence wraps around after 2^32 integers. This
* leaves the upper 32-bits to slave nodes and their jobs.
*/
static uint64
UniqueJobId(void)
{
text *sequenceName = cstring_to_text(JOBID_SEQUENCE_NAME);
Oid sequenceId = ResolveRelationId(sequenceName);
Datum sequenceIdDatum = ObjectIdGetDatum(sequenceId);
/* generate new and unique jobId from sequence */
Datum jobIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
int64 jobId = DatumGetInt64(jobIdDatum);
return jobId;
}
/* Builds a job from the given job query and depended job list. */
static Job *
BuildJob(Query *jobQuery, List *dependedJobList)
{
Job *job = CitusMakeNode(Job);
job->jobId = UniqueJobId();
job->jobQuery = jobQuery;
job->dependedJobList = dependedJobList;
return job;
}
/*
* BuildMapMergeJob builds a MapMerge job from the given query and depended job
* list. The function then copies and updates the logical plan's partition
* column, and uses the join rule type to determine the physical repartitioning
* method to apply.
*/
static MapMergeJob *
BuildMapMergeJob(Query *jobQuery, List *dependedJobList, Var *partitionKey,
PartitionType partitionType, Oid baseRelationId,
BoundaryNodeJobType boundaryNodeJobType)
{
MapMergeJob *mapMergeJob = NULL;
List *rangeTableList = jobQuery->rtable;
Var *partitionColumn = copyObject(partitionKey);
/* update the logical partition key's table and column identifiers */
if (boundaryNodeJobType != SUBQUERY_MAP_MERGE_JOB)
{
UpdateColumnAttributes(partitionColumn, rangeTableList, dependedJobList);
}
mapMergeJob = CitusMakeNode(MapMergeJob);
mapMergeJob->job.jobId = UniqueJobId();
mapMergeJob->job.jobQuery = jobQuery;
mapMergeJob->job.dependedJobList = dependedJobList;
mapMergeJob->partitionColumn = partitionColumn;
mapMergeJob->sortedShardIntervalArrayLength = 0;
/*
* We assume dual partition join defaults to hash partitioning, and single
* partition join defaults to range partitioning. In practice, the join type
* should have no impact on the physical repartitioning (hash/range) method.
* If join type is not set, this means this job represents a subquery, and
* uses hash partitioning.
*/
if (partitionType == HASH_PARTITION_TYPE)
{
uint32 partitionCount = HashPartitionCount();
mapMergeJob->partitionType = HASH_PARTITION_TYPE;
mapMergeJob->partitionCount = partitionCount;
}
else if (partitionType == RANGE_PARTITION_TYPE)
{
/* build the split point object for the table on the right-hand side */
List *shardIntervalList = LoadShardIntervalList(baseRelationId);
uint32 shardCount = (uint32) list_length(shardIntervalList);
ShardInterval **sortedShardIntervalArray =
SortedShardIntervalArray(shardIntervalList);
/* this join-type currently doesn't work for hash partitioned tables */
char basePartitionMethod = PartitionMethod(baseRelationId);
Assert(basePartitionMethod != DISTRIBUTE_BY_HASH);
mapMergeJob->partitionType = RANGE_PARTITION_TYPE;
mapMergeJob->partitionCount = shardCount;
mapMergeJob->sortedShardIntervalArray = sortedShardIntervalArray;
mapMergeJob->sortedShardIntervalArrayLength = shardCount;
}
return mapMergeJob;
}
/*
* HashPartitionCount returns the number of partition files we create for a hash
* partition task. The function follows Hadoop's method for picking the number
* of reduce tasks: 0.95 or 1.75 * node count * max reduces per node. We choose
* the lower constant 0.95 so that all tasks can start immediately, but round it
* to 1.0 so that we have a smooth number of partition tasks.
*/
static uint32
HashPartitionCount(void)
{
uint32 nodeCount = WorkerGetLiveNodeCount();
double maxReduceTasksPerNode = MaxRunningTasksPerNode / 2.0;
uint32 partitionCount = (uint32) rint(nodeCount * maxReduceTasksPerNode);
return partitionCount;
}
/*
* SortedShardIntervalArray returns a sorted array of shard intervals for shards
* in the given shard list. The array elements are sorted in in ascending order
* according to shard interval's minimum value.
*/
ShardInterval **
SortedShardIntervalArray(List *shardIntervalList)
{
FmgrInfo *typeCompareFunction = NULL;
ListCell *shardIntervalCell = NULL;
uint32 shardIntervalIndex = 0;
ShardInterval **shardIntervalArray = NULL;
uint32 shardIntervalCount = (uint32) list_length(shardIntervalList);
Assert(shardIntervalCount > 0);
/* allocate an array for sorted shard intervals */
shardIntervalArray = palloc0(shardIntervalCount * sizeof(ShardInterval *));
/* fill in the array with shard intervals */
foreach(shardIntervalCell, shardIntervalList)
{
ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
if (shardInterval->minValueExists && shardInterval->maxValueExists)
{
shardIntervalArray[shardIntervalIndex] = shardInterval;
}
else
{
ereport(ERROR, (errmsg("cannot range repartition shard " UINT64_FORMAT
" with missing min/max values",
shardInterval->shardId)));
}
/* resolve the datum type and comparison function on first pass */
if (shardIntervalIndex == 0)
{
Oid typeId = shardInterval->valueTypeId;
typeCompareFunction = GetFunctionInfo(typeId, BTREE_AM_OID, BTORDER_PROC);
}
shardIntervalIndex++;
}
/* sort shard intervals by their minimum values in ascending order */
qsort_arg(shardIntervalArray, shardIntervalCount, sizeof(ShardInterval *),
(qsort_arg_comparator) CompareShardIntervals, (void *) typeCompareFunction);
return shardIntervalArray;
}
/*
* CompareShardIntervals acts as a helper function to compare two shard interval
* pointers by their minimum values, using the value's type comparison function.
*/
static int
CompareShardIntervals(const void *leftElement, const void *rightElement,
FmgrInfo *typeCompareFunction)
{
ShardInterval **leftShardInterval = (ShardInterval **) leftElement;
ShardInterval **rightShardInterval = (ShardInterval **) rightElement;
Datum leftDatum = (*leftShardInterval)->minValue;
Datum rightDatum = (*rightShardInterval)->minValue;
Datum comparisonDatum = CompareCall2(typeCompareFunction, leftDatum, rightDatum);
int comparisonResult = DatumGetInt32(comparisonDatum);
return comparisonResult;
}
/*
* SplitPointObject walks over shard intervals in the given array, extracts each
* shard interval's minimum value, sorts and inserts these minimum values into a
* new array. This sorted array is then used by the MapMerge job.
*/
static ArrayType *
SplitPointObject(ShardInterval **shardIntervalArray, uint32 shardIntervalCount)
{
ArrayType *splitPointObject = NULL;
uint32 intervalIndex = 0;
Oid typeId = InvalidOid;
bool typeByValue = false;
char typeAlignment = 0;
int16 typeLength = 0;
/* allocate an array for shard min values */
uint32 minDatumCount = shardIntervalCount;
Datum *minDatumArray = palloc0(minDatumCount * sizeof(Datum));
for (intervalIndex = 0; intervalIndex < shardIntervalCount; intervalIndex++)
{
ShardInterval *shardInterval = shardIntervalArray[intervalIndex];
minDatumArray[intervalIndex] = shardInterval->minValue;
Assert(shardInterval->minValueExists);
/* resolve the datum type on the first pass */
if (intervalIndex == 0)
{
typeId = shardInterval->valueTypeId;
}
}
/* construct the split point object from the sorted array */
get_typlenbyvalalign(typeId, &typeLength, &typeByValue, &typeAlignment);
splitPointObject = construct_array(minDatumArray, minDatumCount, typeId,
typeLength, typeByValue, typeAlignment);
return splitPointObject;
}
/* ------------------------------------------------------------
* Functions that relate to building and assigning tasks follow
* ------------------------------------------------------------
*/
/*
* BuildJobTreeTaskList takes in the given job tree and walks over jobs in this
* tree bottom up. The function then creates tasks for each job in the tree,
* sets dependencies between tasks and their downstream dependencies and assigns
* tasks to worker nodes.
*/
static Job *
BuildJobTreeTaskList(Job *jobTree)
{
List *flattenedJobList = NIL;
uint32 flattenedJobCount = 0;
int32 jobIndex = 0;
/*
* We traverse the job tree in preorder, and append each visited job to our
* flattened list. This way, each job in our list appears before the jobs it
* depends on.
*/
List *jobStack = list_make1(jobTree);
while (jobStack != NIL)
{
Job *job = (Job *) llast(jobStack);
flattenedJobList = lappend(flattenedJobList, job);
/* pop top element and push its children to the stack */
jobStack = list_delete_ptr(jobStack, job);
jobStack = list_union_ptr(jobStack, job->dependedJobList);
}
/*
* We walk the job list in reverse order to visit jobs bottom up. This way,
* we can create dependencies between tasks bottom up, and assign them to
* worker nodes accordingly.
*/
flattenedJobCount = (int32) list_length(flattenedJobList);
for (jobIndex = (flattenedJobCount - 1); jobIndex >= 0; jobIndex--)
{
Job *job = (Job *) list_nth(flattenedJobList, jobIndex);
List *sqlTaskList = NIL;
List *assignedSqlTaskList = NIL;
ListCell *assignedSqlTaskCell = NULL;
/* create sql tasks for the job, and prune redundant data fetch tasks */
if (job->subqueryPushdown)
{
sqlTaskList = SubquerySqlTaskList(job);
}
else
{
sqlTaskList = SqlTaskList(job);
}
sqlTaskList = PruneSqlTaskDependencies(sqlTaskList);
/*
* We first assign sql and merge tasks to worker nodes. Next, we assign
* sql tasks' data fetch dependencies.
*/
assignedSqlTaskList = AssignTaskList(sqlTaskList);
AssignDataFetchDependencies(assignedSqlTaskList);
/* now assign merge task's data fetch dependencies */
foreach(assignedSqlTaskCell, assignedSqlTaskList)
{
Task *assignedSqlTask = (Task *) lfirst(assignedSqlTaskCell);
List *assignedMergeTaskList = FindDependedMergeTaskList(assignedSqlTask);
AssignDataFetchDependencies(assignedMergeTaskList);
}
/*
* If we have a MapMerge job, the map tasks in this job wrap around the
* SQL tasks and their assignments.
*/
if (CitusIsA(job, MapMergeJob))
{
MapMergeJob *mapMergeJob = (MapMergeJob *) job;
uint32 taskIdIndex = TaskListHighestTaskId(assignedSqlTaskList) + 1;
List *mapTaskList = MapTaskList(mapMergeJob, assignedSqlTaskList);
List *mergeTaskList = MergeTaskList(mapMergeJob, mapTaskList, taskIdIndex);
mapMergeJob->mapTaskList = mapTaskList;
mapMergeJob->mergeTaskList = mergeTaskList;
}
else
{
job->taskList = assignedSqlTaskList;
}
}
return jobTree;
}
/*
* SubquerySqlTaskList creates a list of SQL tasks to execute the given subquery
* pushdown job. For this, it gets all range tables in the subquery tree, then
* walks over each range table in the list, gets shards for each range table,
* and prunes unneeded shards. Then for remaining shards, fragments are created
* and merged to create fragment combinations. For each created combination, the
* function builds a SQL task, and appends this task to a task list.
*/
static List *
SubquerySqlTaskList(Job *job)
{
Query *subquery = job->jobQuery;
uint64 jobId = job->jobId;
List *sqlTaskList = NIL;
List *fragmentCombinationList = NIL;
List *opExpressionList = NIL;
List *queryList = NIL;
List *rangeTableList = NIL;
ListCell *fragmentCombinationCell = NULL;
ListCell *rangeTableCell = NULL;
ListCell *queryCell = NULL;
Node *whereClauseTree = NULL;
uint32 taskIdIndex = 1; /* 0 is reserved for invalid taskId */
uint32 anchorRangeTableId = 0;
uint32 rangeTableIndex = 0;
const uint32 fragmentSize = sizeof(RangeTableFragment);
/* find filters on partition columns */
ExtractQueryWalker((Node *) subquery, &queryList);
foreach(queryCell, queryList)
{
Query *query = (Query *) lfirst(queryCell);
bool leafQuery = LeafQuery(query);
if (!leafQuery)
{
continue;
}
/* we have some filters on partition column */
opExpressionList = PartitionColumnOpExpressionList(query);
if (opExpressionList != NIL)
{
break;
}
}
/* get list of all range tables in subquery tree */
ExtractRangeTableRelationWalker((Node *) subquery, &rangeTableList);
anchorRangeTableId = AnchorRangeTableId(rangeTableList);
/*
* For each range table entry, first we prune shards for the relation
* referenced in the range table. Then we sort remaining shards and create
* fragments in this order and add these fragments to fragment combination
* list.
*/
foreach(rangeTableCell, rangeTableList)
{
RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
Oid relationId = rangeTableEntry->relid;
List *shardIntervalList = LoadShardIntervalList(relationId);
List *finalShardIntervalList = NIL;
ListCell *fragmentCombinationCell = NULL;
ShardInterval **sortedIntervalArray = NULL;
uint32 tableId = rangeTableIndex + 1; /* tableId starts from 1 */
uint32 finalShardCount = 0;
uint32 shardIndex = 0;
if (opExpressionList != NIL)
{
Var *partitionColumn = PartitionColumn(relationId, tableId);
List *whereClauseList = ReplaceColumnsInOpExpressionList(opExpressionList,
partitionColumn);
finalShardIntervalList = PruneShardList(relationId, tableId, whereClauseList,
shardIntervalList);
}
else
{
finalShardIntervalList = shardIntervalList;
}
/* if all shards are pruned away, we return an empty task list */
finalShardCount = list_length(finalShardIntervalList);
if (finalShardCount == 0)
{
return NIL;
}
sortedIntervalArray = SortedShardIntervalArray(finalShardIntervalList);
fragmentCombinationCell = list_head(fragmentCombinationList);
for (shardIndex = 0; shardIndex < finalShardCount; shardIndex++)
{
ShardInterval *shardInterval = sortedIntervalArray[shardIndex];
RangeTableFragment *shardFragment = palloc0(fragmentSize);
shardFragment->fragmentReference = &(shardInterval->shardId);
shardFragment->fragmentType = CITUS_RTE_RELATION;
shardFragment->rangeTableId = tableId;
if (tableId == 1)
{
List *fragmentCombination = list_make1(shardFragment);
fragmentCombinationList = lappend(fragmentCombinationList,
fragmentCombination);
}
else
{
List *fragmentCombination = (List *) lfirst(fragmentCombinationCell);
fragmentCombination = lappend(fragmentCombination, shardFragment);
/* get next fragment for the first relation list */
fragmentCombinationCell = lnext(fragmentCombinationCell);
}
}
rangeTableIndex++;
}
/*
* Ands are made implicit during shard pruning, as predicate comparison and
* refutation depend on it being so. We need to make them explicit again so
* that the query string is generated as (...) AND (...) as opposed to
* (...), (...).
*/
whereClauseTree = (Node *) make_ands_explicit((List *) subquery->jointree->quals);
subquery->jointree->quals = whereClauseTree;
/* create tasks from every fragment combination */
foreach(fragmentCombinationCell, fragmentCombinationList)
{
List *fragmentCombination = (List *) lfirst(fragmentCombinationCell);
List *taskRangeTableList = NIL;
Query *taskQuery = copyObject(subquery);
Task *sqlTask = NULL;
StringInfo sqlQueryString = NULL;
/* create tasks to fetch fragments required for the sql task */
List *uniqueFragmentList = UniqueFragmentList(fragmentCombination);
List *dataFetchTaskList = DataFetchTaskList(jobId, taskIdIndex,
uniqueFragmentList);
int32 dataFetchTaskCount = list_length(dataFetchTaskList);
taskIdIndex += dataFetchTaskCount;
ExtractRangeTableRelationWalker((Node *) taskQuery, &taskRangeTableList);
UpdateRangeTableAlias(taskRangeTableList, fragmentCombination);
/* transform the updated task query to a SQL query string */
sqlQueryString = makeStringInfo();
pg_get_query_def(taskQuery, sqlQueryString);
sqlTask = CreateBasicTask(jobId, taskIdIndex, SQL_TASK, sqlQueryString->data);
sqlTask->dependedTaskList = dataFetchTaskList;
/* log the query string we generated */
ereport(DEBUG4, (errmsg("generated sql query for job " UINT64_FORMAT
" and task %d", sqlTask->jobId, sqlTask->taskId),
errdetail("query string: \"%s\"", sqlQueryString->data)));
sqlTask->anchorShardId = AnchorShardId(fragmentCombination, anchorRangeTableId);
taskIdIndex++;
sqlTaskList = lappend(sqlTaskList, sqlTask);
}
return sqlTaskList;
}
/*
* SqlTaskList creates a list of SQL tasks to execute the given job. For this,
* the function walks over each range table in the job's range table list, gets
* each range table's table fragments, and prunes unneeded table fragments. The
* function then joins table fragments from different range tables, and creates
* all fragment combinations. For each created combination, the function builds
* a SQL task, and appends this task to a task list.
*/
static List *
SqlTaskList(Job *job)
{
List *sqlTaskList = NIL;
uint32 taskIdIndex = 1; /* 0 is reserved for invalid taskId */
uint64 jobId = job->jobId;
bool anchorRangeTableBasedAssignment = false;
uint32 anchorRangeTableId = 0;
Node *whereClauseTree = NULL;
List *rangeTableFragmentsList = NIL;
List *fragmentCombinationList = NIL;
ListCell *fragmentCombinationCell = NULL;
Query *jobQuery = job->jobQuery;
List *rangeTableList = jobQuery->rtable;
List *whereClauseList = (List *) jobQuery->jointree->quals;
List *dependedJobList = job->dependedJobList;
/*
* If we don't depend on a hash partition, then we determine the largest
* table around which we build our queries. This reduces data fetching.
*/
bool dependsOnHashPartitionJob = DependsOnHashPartitionJob(job);
if (!dependsOnHashPartitionJob)
{
anchorRangeTableBasedAssignment = true;
anchorRangeTableId = AnchorRangeTableId(rangeTableList);
Assert(anchorRangeTableId != 0);
Assert(anchorRangeTableId <= list_length(rangeTableList));
}
/* adjust our column old attributes for partition pruning to work */
AdjustColumnOldAttributes(whereClauseList);
AdjustColumnOldAttributes(jobQuery->targetList);
/*
* Ands are made implicit during shard pruning, as predicate comparison and
* refutation depend on it being so. We need to make them explicit again so
* that the query string is generated as (...) AND (...) as opposed to
* (...), (...).
*/
whereClauseTree = (Node *) make_ands_explicit((List *) jobQuery->jointree->quals);
jobQuery->jointree->quals = whereClauseTree;
/*
* For each range table, we first get a list of their shards or merge tasks.
* We also apply partition pruning based on the selection criteria. If all
* range table fragments are pruned away, we return an empty task list.
*/
rangeTableFragmentsList = RangeTableFragmentsList(rangeTableList, whereClauseList,
dependedJobList);
if (rangeTableFragmentsList == NIL)
{
return NIL;
}
/*
* We then generate fragment combinations according to how range tables join
* with each other (and apply join pruning). Each fragment combination then
* represents one SQL task's dependencies.
*/
fragmentCombinationList = FragmentCombinationList(rangeTableFragmentsList,
jobQuery, dependedJobList);
fragmentCombinationCell = NULL;
foreach(fragmentCombinationCell, fragmentCombinationList)
{
List *fragmentCombination = (List *) lfirst(fragmentCombinationCell);
List *dataFetchTaskList = NIL;
int32 dataFetchTaskCount = 0;
StringInfo sqlQueryString = NULL;
Task *sqlTask = NULL;
Query *taskQuery = NULL;
List *fragmentRangeTableList = NIL;
/* create tasks to fetch fragments required for the sql task */
dataFetchTaskList = DataFetchTaskList(jobId, taskIdIndex, fragmentCombination);
dataFetchTaskCount = list_length(dataFetchTaskList);
taskIdIndex += dataFetchTaskCount;
/* update range table entries with fragment aliases (in place) */
taskQuery = copyObject(jobQuery);
fragmentRangeTableList = taskQuery->rtable;
UpdateRangeTableAlias(fragmentRangeTableList, fragmentCombination);
/* transform the updated task query to a SQL query string */
sqlQueryString = makeStringInfo();
pg_get_query_def(taskQuery, sqlQueryString);
sqlTask = CreateBasicTask(jobId, taskIdIndex, SQL_TASK, sqlQueryString->data);
sqlTask->dependedTaskList = dataFetchTaskList;
/* log the query string we generated */
ereport(DEBUG4, (errmsg("generated sql query for job " UINT64_FORMAT
" and task %d", sqlTask->jobId, sqlTask->taskId),
errdetail("query string: \"%s\"", sqlQueryString->data)));
sqlTask->anchorShardId = INVALID_SHARD_ID;
if (anchorRangeTableBasedAssignment)
{
sqlTask->anchorShardId = AnchorShardId(fragmentCombination,
anchorRangeTableId);
}
taskIdIndex++;
sqlTaskList = lappend(sqlTaskList, sqlTask);
}
return sqlTaskList;
}
/*
* DependsOnHashPartitionJob checks if the given job depends on a hash
* partitioning job.
*/
static bool
DependsOnHashPartitionJob(Job *job)
{
bool dependsOnHashPartitionJob = false;
List *dependedJobList = job->dependedJobList;
uint32 dependedJobCount = (uint32) list_length(dependedJobList);
if (dependedJobCount > 0)
{
Job *dependedJob = (Job *) linitial(dependedJobList);
if (CitusIsA(dependedJob, MapMergeJob))
{
MapMergeJob *mapMergeJob = (MapMergeJob *) dependedJob;
if (mapMergeJob->partitionType == HASH_PARTITION_TYPE)
{
dependsOnHashPartitionJob = true;
}
}
}
return dependsOnHashPartitionJob;
}
/*
* AnchorRangeTableId determines the table around which we build our queries,
* and returns this table's range table id. We refer to this table as the anchor
* table, and make sure that the anchor table's shards are moved or cached only
* when absolutely necessary.
*/
static uint32
AnchorRangeTableId(List *rangeTableList)
{
uint32 anchorRangeTableId = 0;
uint64 maxTableSize = 0;
/*
* We first filter anything but ordinary tables. Then, we pick the table(s)
* with the most number of shards as our anchor table. If multiple tables
* have the most number of shards, we have a draw.
*/
List *baseTableIdList = BaseRangeTableIdList(rangeTableList);
List *anchorTableIdList = AnchorRangeTableIdList(rangeTableList, baseTableIdList);
ListCell *anchorTableIdCell = NULL;
int anchorTableIdCount = list_length(anchorTableIdList);
Assert(anchorTableIdCount > 0);
if (anchorTableIdCount == 1)
{
anchorRangeTableId = (uint32) linitial_int(anchorTableIdList);
return anchorRangeTableId;
}
/*
* If more than one table has the most number of shards, we break the draw
* by comparing table sizes and picking the table with the largest size.
*/
foreach(anchorTableIdCell, anchorTableIdList)
{
uint32 anchorTableId = (uint32) lfirst_int(anchorTableIdCell);
RangeTblEntry *tableEntry = rt_fetch(anchorTableId, rangeTableList);
uint64 tableSize = 0;
List *shardList = LoadShardList(tableEntry->relid);
ListCell *shardCell = NULL;
foreach(shardCell, shardList)
{
uint64 *shardIdPointer = (uint64 *) lfirst(shardCell);
uint64 shardId = (*shardIdPointer);
uint64 shardSize = ShardLength(shardId);
tableSize += shardSize;
}
if (tableSize > maxTableSize)
{
maxTableSize = tableSize;
anchorRangeTableId = anchorTableId;
}
}
if (anchorRangeTableId == 0)
{
/* all tables have the same shard count and size 0, pick the first */
anchorRangeTableId = (uint32) linitial_int(anchorTableIdList);
}
return anchorRangeTableId;
}
/*
* BaseRangeTableIdList walks over range tables in the given range table list,
* finds range tables that correspond to base (non-repartitioned) tables, and
* returns these range tables' identifiers in a new list.
*/
static List *
BaseRangeTableIdList(List *rangeTableList)
{
List *baseRangeTableIdList = NIL;
uint32 rangeTableId = 1;
ListCell *rangeTableCell = NULL;
foreach(rangeTableCell, rangeTableList)
{
RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
if (GetRangeTblKind(rangeTableEntry) == CITUS_RTE_RELATION)
{
baseRangeTableIdList = lappend_int(baseRangeTableIdList, rangeTableId);
}
rangeTableId++;
}
return baseRangeTableIdList;
}
/*
* AnchorRangeTableIdList finds ordinary table(s) with the most number of shards
* and returns the corresponding range table id(s) in a list.
*/
static List *
AnchorRangeTableIdList(List *rangeTableList, List *baseRangeTableIdList)
{
List *anchorTableIdList = NIL;
uint32 maxShardCount = 0;
ListCell *baseRangeTableIdCell = NULL;
uint32 baseRangeTableCount = list_length(baseRangeTableIdList);
if (baseRangeTableCount == 1)
{
return baseRangeTableIdList;
}
foreach(baseRangeTableIdCell, baseRangeTableIdList)
{
uint32 baseRangeTableId = (uint32) lfirst_int(baseRangeTableIdCell);
RangeTblEntry *tableEntry = rt_fetch(baseRangeTableId, rangeTableList);
List *shardList = LoadShardList(tableEntry->relid);
uint32 shardCount = (uint32) list_length(shardList);
if (shardCount > maxShardCount)
{
anchorTableIdList = list_make1_int(baseRangeTableId);
maxShardCount = shardCount;
}
else if (shardCount == maxShardCount)
{
anchorTableIdList = lappend_int(anchorTableIdList, baseRangeTableId);
}
}
return anchorTableIdList;
}
/*
* AdjustColumnOldAttributes adjust the old tableId (varnoold) and old columnId
* (varoattno), and sets them equal to the new values. We need this adjustment
* for partition pruning where we compare these columns with partition columns
* loaded from system catalogs. Since columns loaded from system catalogs always
* have the same old and new values, we also need to adjust column values here.
*/
static void
AdjustColumnOldAttributes(List *expressionList)
{
List *columnList = pull_var_clause_default((Node *) expressionList);
ListCell *columnCell = NULL;
foreach(columnCell, columnList)
{
Var *column = (Var *) lfirst(columnCell);
column->varnoold = column->varno;
column->varoattno = column->varattno;
}
}
/*
* RangeTableFragmentsList walks over range tables in the given range table list
* and for each table, the function creates a list of its fragments. A fragment
* in this list represents either a regular shard or a merge task. Once a list
* for each range table is constructed, the function applies partition pruning
* using the given where clause list. Then, the function appends the fragment
* list for each range table to a list of lists, and returns this list of lists.
*/
static List *
RangeTableFragmentsList(List *rangeTableList, List *whereClauseList,
List *dependedJobList)
{
List *rangeTableFragmentsList = NIL;
uint32 rangeTableIndex = 0;
const uint32 fragmentSize = sizeof(RangeTableFragment);
ListCell *rangeTableCell = NULL;
foreach(rangeTableCell, rangeTableList)
{
uint32 tableId = rangeTableIndex + 1; /* tableId starts from 1 */
RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
CitusRTEKind rangeTableKind = GetRangeTblKind(rangeTableEntry);
if (rangeTableKind == CITUS_RTE_RELATION)
{
Oid relationId = rangeTableEntry->relid;
ListCell *shardIntervalCell = NULL;
List *shardFragmentList = NIL;
List *shardIntervalList = LoadShardIntervalList(relationId);
List *prunedShardIntervalList = PruneShardList(relationId, tableId,
whereClauseList,
shardIntervalList);
/*
* If we prune all shards for one table, query results will be empty.
* We can therefore return NIL for the task list here.
*/
if (prunedShardIntervalList == NIL)
{
return NIL;
}
foreach(shardIntervalCell, prunedShardIntervalList)
{
ShardInterval *shardInterval =
(ShardInterval *) lfirst(shardIntervalCell);
RangeTableFragment *shardFragment = palloc0(fragmentSize);
shardFragment->fragmentReference = &shardInterval->shardId;
shardFragment->fragmentType = CITUS_RTE_RELATION;
shardFragment->rangeTableId = tableId;
shardFragmentList = lappend(shardFragmentList, shardFragment);
}
rangeTableFragmentsList = lappend(rangeTableFragmentsList,
shardFragmentList);
}
else if (rangeTableKind == CITUS_RTE_REMOTE_QUERY)
{
MapMergeJob *dependedMapMergeJob = NULL;
List *mergeTaskFragmentList = NIL;
List *mergeTaskList = NIL;
ListCell *mergeTaskCell = NULL;
Job *dependedJob = JobForRangeTable(dependedJobList, rangeTableEntry);
Assert(CitusIsA(dependedJob, MapMergeJob));
dependedMapMergeJob = (MapMergeJob *) dependedJob;
mergeTaskList = dependedMapMergeJob->mergeTaskList;
/* if there are no tasks for the depended job, just return NIL */
if (mergeTaskList == NIL)
{
return NIL;
}
foreach(mergeTaskCell, mergeTaskList)
{
Task *mergeTask = (Task *) lfirst(mergeTaskCell);
RangeTableFragment *mergeTaskFragment = palloc0(fragmentSize);
mergeTaskFragment->fragmentReference = mergeTask;
mergeTaskFragment->fragmentType = CITUS_RTE_REMOTE_QUERY;
mergeTaskFragment->rangeTableId = tableId;
mergeTaskFragmentList = lappend(mergeTaskFragmentList, mergeTaskFragment);
}
rangeTableFragmentsList = lappend(rangeTableFragmentsList,
mergeTaskFragmentList);
}
rangeTableIndex++;
}
return rangeTableFragmentsList;
}
/*
* PruneShardList prunes shard intervals from given list based on the selection criteria,
* and returns remaining shard intervals in another list.
*/
List *
PruneShardList(Oid relationId, Index tableId, List *whereClauseList,
List *shardIntervalList)
{
List *remainingShardList = NIL;
ListCell *shardIntervalCell = NULL;
List *restrictInfoList = NIL;
Node *baseConstraint = NULL;
Var *partitionColumn = PartitionColumn(relationId, tableId);
char partitionMethod = PartitionMethod(relationId);
/* build the filter clause list for the partition method */
if (partitionMethod == DISTRIBUTE_BY_HASH)
{
Node *hashedNode = HashableClauseMutator((Node *) whereClauseList,
partitionColumn);
List *hashedClauseList = (List *) hashedNode;
restrictInfoList = BuildRestrictInfoList(hashedClauseList);
}
else
{
restrictInfoList = BuildRestrictInfoList(whereClauseList);
}
/* override the partition column for hash partitioning */
if (partitionMethod == DISTRIBUTE_BY_HASH)
{
partitionColumn = MakeInt4Column();
}
/* build the base expression for constraint */
baseConstraint = BuildBaseConstraint(partitionColumn);
/* walk over shard list and check if shards can be pruned */
foreach(shardIntervalCell, shardIntervalList)
{
ShardInterval *shardInterval = (ShardInterval *) lfirst(shardIntervalCell);
List *constraintList = NIL;
bool shardPruned = false;
if (shardInterval->minValueExists && shardInterval->maxValueExists)
{
/* set the min/max values in the base constraint */
UpdateConstraint(baseConstraint, shardInterval);
constraintList = list_make1(baseConstraint);
shardPruned = predicate_refuted_by(constraintList, restrictInfoList);
}
if (shardPruned)
{
ereport(DEBUG2, (errmsg("predicate pruning for shardId "
UINT64_FORMAT, shardInterval->shardId)));
}
else
{
remainingShardList = lappend(remainingShardList, shardInterval);
}
}
return remainingShardList;
}
/*
* BuildBaseConstraint builds and returns a base constraint. This constraint
* implements an expression in the form of (column <= max && column >= min),
* where column is the partition key, and min and max values represent a shard's
* min and max values. These shard values are filled in after the constraint is
* built.
*/
Node *
BuildBaseConstraint(Var *column)
{
Node *baseConstraint = NULL;
OpExpr *lessThanExpr = NULL;
OpExpr *greaterThanExpr = NULL;
/* Build these expressions with only one argument for now */
lessThanExpr = MakeOpExpression(column, BTLessEqualStrategyNumber);
greaterThanExpr = MakeOpExpression(column, BTGreaterEqualStrategyNumber);
/* Build base constaint as an and of two qual conditions */
baseConstraint = make_and_qual((Node *) lessThanExpr, (Node *) greaterThanExpr);
return baseConstraint;
}
/*
* MakeOpExpression builds an operator expression node. This operator expression
* implements the operator clause as defined by the variable and the strategy
* number.
*/
OpExpr *
MakeOpExpression(Var *variable, int16 strategyNumber)
{
Oid typeId = variable->vartype;
Oid typeModId = variable->vartypmod;
Oid collationId = variable->varcollid;
OperatorCacheEntry *operatorCacheEntry = NULL;
Oid accessMethodId = BTREE_AM_OID;
Oid operatorId = InvalidOid;
Oid operatorClassInputType = InvalidOid;
Const *constantValue = NULL;
OpExpr *expression = NULL;
char typeType = 0;
operatorCacheEntry = LookupOperatorByType(typeId, accessMethodId, strategyNumber);
operatorId = operatorCacheEntry->operatorId;
operatorClassInputType = operatorCacheEntry->operatorClassInputType;
typeType = operatorCacheEntry->typeType;
/*
* Relabel variable if input type of default operator class is not equal to
* the variable type. Note that we don't relabel the variable if the default
* operator class variable type is a pseudo-type.
*/
if (operatorClassInputType != typeId && typeType != TYPTYPE_PSEUDO)
{
variable = (Var *) makeRelabelType((Expr *) variable, operatorClassInputType,
-1, collationId, COERCE_IMPLICIT_CAST);
}
constantValue = makeNullConst(operatorClassInputType, typeModId, collationId);
/* Now make the expression with the given variable and a null constant */
expression = (OpExpr *) make_opclause(operatorId,
InvalidOid, /* no result type yet */
false, /* no return set */
(Expr *) variable,
(Expr *) constantValue,
InvalidOid, collationId);
/* Set implementing function id and result type */
expression->opfuncid = get_opcode(operatorId);
expression->opresulttype = get_func_rettype(expression->opfuncid);
return expression;
}
/*
* LookupOperatorByType is a wrapper around GetOperatorByType(),
* operatorClassInputType() and get_typtype() functions that uses a cache to avoid
* multiple lookups of operators and its related fields within a single session by
* their types, access methods and strategy numbers.
* LookupOperatorByType function errors out if it cannot find corresponding
* default operator class with the given parameters on the system catalogs.
*/
static OperatorCacheEntry *
LookupOperatorByType(Oid typeId, Oid accessMethodId, int16 strategyNumber)
{
OperatorCacheEntry *matchingCacheEntry = NULL;
ListCell *cacheEntryCell = NULL;
/* search the cache */
foreach(cacheEntryCell, OperatorCache)
{
OperatorCacheEntry *cacheEntry = lfirst(cacheEntryCell);
if ((cacheEntry->typeId == typeId) &&
(cacheEntry->accessMethodId == accessMethodId) &&
(cacheEntry->strategyNumber == strategyNumber))
{
matchingCacheEntry = cacheEntry;
break;
}
}
/* if not found in the cache, call GetOperatorByType and put the result in cache */
if (matchingCacheEntry == NULL)
{
MemoryContext oldContext = NULL;
Oid operatorClassId = GetDefaultOpClass(typeId, accessMethodId);
Oid operatorId = InvalidOid;
Oid operatorClassInputType = InvalidOid;
char typeType = InvalidOid;
if (operatorClassId == InvalidOid)
{
/* if operatorId is invalid, error out */
ereport(ERROR, (errmsg("cannot find default operator class for type:%d,"
" access method: %d", typeId, accessMethodId)));
}
/* fill the other fields to the cache */
operatorId = GetOperatorByType(typeId, accessMethodId, strategyNumber);
operatorClassInputType = get_opclass_input_type(operatorClassId);
typeType = get_typtype(operatorClassInputType);
/* make sure we've initialized CacheMemoryContext */
if (CacheMemoryContext == NULL)
{
CreateCacheMemoryContext();
}
oldContext = MemoryContextSwitchTo(CacheMemoryContext);
matchingCacheEntry = palloc0(sizeof(OperatorCacheEntry));
matchingCacheEntry->typeId = typeId;
matchingCacheEntry->accessMethodId = accessMethodId;
matchingCacheEntry->strategyNumber = strategyNumber;
matchingCacheEntry->operatorId = operatorId;
matchingCacheEntry->operatorClassInputType = operatorClassInputType;
matchingCacheEntry->typeType = typeType;
OperatorCache = lappend(OperatorCache, matchingCacheEntry);
MemoryContextSwitchTo(oldContext);
}
return matchingCacheEntry;
}
/*
* GetOperatorByType returns the operator oid for the given type, access method,
* and strategy number.
*/
static Oid
GetOperatorByType(Oid typeId, Oid accessMethodId, int16 strategyNumber)
{
/* Get default operator class from pg_opclass */
Oid operatorClassId = GetDefaultOpClass(typeId, accessMethodId);
Oid operatorFamily = get_opclass_family(operatorClassId);
Oid operatorClassInputType = get_opclass_input_type(operatorClassId);
/* Lookup for the operator with the desired input type in the family */
Oid operatorId = get_opfamily_member(operatorFamily, operatorClassInputType,
operatorClassInputType, strategyNumber);
return operatorId;
}
/*
* SimpleOpExpression checks that given expression is a simple operator
* expression. A simple operator expression is a binary operator expression with
* operands of a var and a non-null constant.
*/
bool
SimpleOpExpression(Expr *clause)
{
Node *leftOperand = NULL;
Node *rightOperand = NULL;
Const *constantClause = NULL;
if (is_opclause(clause) && list_length(((OpExpr *) clause)->args) == 2)
{
leftOperand = get_leftop(clause);
rightOperand = get_rightop(clause);
}
else
{
return false; /* not a binary opclause */
}
/* strip coercions before doing check */
leftOperand = strip_implicit_coercions(leftOperand);
rightOperand = strip_implicit_coercions(rightOperand);
if (IsA(rightOperand, Const) && IsA(leftOperand, Var))
{
constantClause = (Const *) rightOperand;
}
else if (IsA(leftOperand, Const) && IsA(rightOperand, Var))
{
constantClause = (Const *) leftOperand;
}
else
{
return false;
}
if (constantClause->constisnull)
{
return false;
}
return true;
}
/*
* HashableClauseMutator walks over the original where clause list, replaces
* hashable nodes with hashed versions and keeps other nodes as they are.
*/
static Node *
HashableClauseMutator(Node *originalNode, Var *partitionColumn)
{
Node *newNode = NULL;
if (originalNode == NULL)
{
return NULL;
}
if (IsA(originalNode, OpExpr))
{
OpExpr *operatorExpression = (OpExpr *) originalNode;
bool hasPartitionColumn = false;
Oid leftHashFunction = InvalidOid;
Oid rightHashFunction = InvalidOid;
bool hasHashFunction = get_op_hash_functions(operatorExpression->opno,
&leftHashFunction,
&rightHashFunction);
bool simpleOpExpression = SimpleOpExpression((Expr *) operatorExpression);
if (simpleOpExpression)
{
hasPartitionColumn = OpExpressionContainsColumn(operatorExpression,
partitionColumn);
}
if (hasHashFunction && hasPartitionColumn)
{
OpExpr *hashedOperatorExpression =
MakeHashedOperatorExpression((OpExpr *) originalNode);
newNode = (Node *) hashedOperatorExpression;
}
}
else if (IsA(originalNode, NullTest))
{
NullTest *nullTest = (NullTest *) originalNode;
Var *column = NULL;
Expr *nullTestOperand = nullTest->arg;
if (IsA(nullTestOperand, Var))
{
column = (Var *) nullTestOperand;
}
if ((column != NULL) && equal(column, partitionColumn) &&
(nullTest->nulltesttype == IS_NULL))
{
OpExpr *opExpressionWithZeroConst = MakeOpExpressionWithZeroConst();
newNode = (Node *) opExpressionWithZeroConst;
}
}
else if (IsA(originalNode, ScalarArrayOpExpr))
{
ereport(NOTICE, (errmsg("cannot use shard pruning with ANY (array expression)"),
errhint("Consider rewriting the expression with OR clauses.")));
}
/*
* If this node is not hashable, continue walking down the expression tree
* to find and hash clauses which are eligible.
*/
if (newNode == NULL)
{
newNode = expression_tree_mutator(originalNode, HashableClauseMutator,
(void *) partitionColumn);
}
return newNode;
}
/*
* OpExpressionContainsColumn checks if the operator expression contains the
* given partition column. We assume that given operator expression is a simple
* operator expression which means it is a binary operator expression with
* operands of a var and a non-null constant.
*/
static bool
OpExpressionContainsColumn(OpExpr *operatorExpression, Var *partitionColumn)
{
Node *leftOperand = get_leftop((Expr *) operatorExpression);
Node *rightOperand = get_rightop((Expr *) operatorExpression);
Var *column = NULL;
/* strip coercions before doing check */
leftOperand = strip_implicit_coercions(leftOperand);
rightOperand = strip_implicit_coercions(rightOperand);
if (IsA(leftOperand, Var))
{
column = (Var *) leftOperand;
}
else
{
column = (Var *) rightOperand;
}
return equal(column, partitionColumn);
}
/*
* MakeHashedOperatorExpression creates a new operator expression with a column
* of int4 type and hashed constant value.
*/
static OpExpr *
MakeHashedOperatorExpression(OpExpr *operatorExpression)
{
const Oid hashResultTypeId = INT4OID;
TypeCacheEntry *hashResultTypeEntry = NULL;
Oid operatorId = InvalidOid;
OpExpr *hashedExpression = NULL;
Var *hashedColumn = NULL;
Datum hashedValue = 0;
Const *hashedConstant = NULL;
FmgrInfo *hashFunction = NULL;
TypeCacheEntry *typeEntry = NULL;
Node *leftOperand = get_leftop((Expr *) operatorExpression);
Node *rightOperand = get_rightop((Expr *) operatorExpression);
Const *constant = NULL;
if (IsA(rightOperand, Const))
{
constant = (Const *) rightOperand;
}
else
{
constant = (Const *) leftOperand;
}
/* Load the operator from type cache */
hashResultTypeEntry = lookup_type_cache(hashResultTypeId, TYPECACHE_EQ_OPR);
operatorId = hashResultTypeEntry->eq_opr;
/* Get a column with int4 type */
hashedColumn = MakeInt4Column();
/* Load the hash function from type cache */
typeEntry = lookup_type_cache(constant->consttype, TYPECACHE_HASH_PROC_FINFO);
hashFunction = &(typeEntry->hash_proc_finfo);
if (!OidIsValid(hashFunction->fn_oid))
{
ereport(ERROR, (errcode(ERRCODE_UNDEFINED_FUNCTION),
errmsg("could not identify a hash function for type %s",
format_type_be(constant->consttype)),
errdatatype(constant->consttype)));
}
/*
* Note that any changes to PostgreSQL's hashing functions will change the
* new value created by this function.
*/
hashedValue = FunctionCall1(hashFunction, constant->constvalue);
hashedConstant = MakeInt4Constant(hashedValue);
/* Now create the expression with modified partition column and hashed constant */
hashedExpression = (OpExpr *) make_opclause(operatorId,
InvalidOid, /* no result type yet */
false, /* no return set */
(Expr *) hashedColumn,
(Expr *) hashedConstant,
InvalidOid, InvalidOid);
/* Set implementing function id and result type */
hashedExpression->opfuncid = get_opcode(operatorId);
hashedExpression->opresulttype = get_func_rettype(hashedExpression->opfuncid);
return hashedExpression;
}
/*
* MakeInt4Column creates a column of int4 type with invalid table id and max
* attribute number.
*/
static Var *
MakeInt4Column()
{
Index tableId = 0;
AttrNumber columnAttributeNumber = RESERVED_HASHED_COLUMN_ID;
Oid columnType = INT4OID;
int32 columnTypeMod = -1;
Oid columnCollationOid = InvalidOid;
Index columnLevelSup = 0;
Var *int4Column = makeVar(tableId, columnAttributeNumber, columnType,
columnTypeMod, columnCollationOid, columnLevelSup);
return int4Column;
}
/*
* MakeInt4Constant creates a new constant of int4 type and assigns the given
* value as a constant value.
*/
static Const *
MakeInt4Constant(Datum constantValue)
{
Oid constantType = INT4OID;
int32 constantTypeMode = -1;
Oid constantCollationId = InvalidOid;
int constantLength = sizeof(int32);
bool constantIsNull = false;
bool constantByValue = true;
Const *int4Constant = makeConst(constantType, constantTypeMode, constantCollationId,
constantLength, constantValue, constantIsNull,
constantByValue);
return int4Constant;
}
/*
* MakeOpExpressionWithZeroConst creates a new operator expression with equality
* check to zero and returns it.
*/
static OpExpr *
MakeOpExpressionWithZeroConst()
{
Var *int4Column = MakeInt4Column();
OpExpr *operatorExpression = MakeOpExpression(int4Column, BTEqualStrategyNumber);
Const *constant = (Const *) get_rightop((Expr *) operatorExpression);
constant->constvalue = Int32GetDatum(0);
constant->constisnull = false;
return operatorExpression;
}
/*
* BuildRestrictInfoList builds restrict info list using the selection criteria,
* and then return this list. Note that this function assumes there is only one
* relation for now.
*/
static List *
BuildRestrictInfoList(List *qualList)
{
List *restrictInfoList = NIL;
ListCell *qualCell = NULL;
foreach(qualCell, qualList)
{
RestrictInfo *restrictInfo = NULL;
Node *qualNode = (Node *) lfirst(qualCell);
restrictInfo = make_simple_restrictinfo((Expr *) qualNode);
restrictInfoList = lappend(restrictInfoList, restrictInfo);
}
return restrictInfoList;
}
/* Updates the base constraint with the given min/max values. */
void
UpdateConstraint(Node *baseConstraint, ShardInterval *shardInterval)
{
BoolExpr *andExpr = (BoolExpr *) baseConstraint;
Node *lessThanExpr = (Node *) linitial(andExpr->args);
Node *greaterThanExpr = (Node *) lsecond(andExpr->args);
Node *minNode = get_rightop((Expr *) greaterThanExpr); /* right op */
Node *maxNode = get_rightop((Expr *) lessThanExpr); /* right op */
Const *minConstant = NULL;
Const *maxConstant = NULL;
Assert(shardInterval != NULL);
Assert(shardInterval->minValueExists);
Assert(shardInterval->maxValueExists);
Assert(IsA(minNode, Const));
Assert(IsA(maxNode, Const));
minConstant = (Const *) minNode;
maxConstant = (Const *) maxNode;
minConstant->constvalue = shardInterval->minValue;
maxConstant->constvalue = shardInterval->maxValue;
minConstant->constisnull = false;
maxConstant->constisnull = false;
}
/*
* FragmentCombinationList first builds an ordered sequence of range tables that
* join together. The function then iteratively adds fragments from each joined
* range table, and forms fragment combinations (lists) that cover all tables.
* While doing so, the function also performs join pruning to remove unnecessary
* fragment pairs. Last, the function adds each fragment combination (list) to a
* list, and returns this list.
*/
static List *
FragmentCombinationList(List *rangeTableFragmentsList, Query *jobQuery,
List *dependedJobList)
{
List *fragmentCombinationList = NIL;
JoinSequenceNode *joinSequenceArray = NULL;
List *fragmentCombinationQueue = NIL;
List *emptyList = NIL;
/* find a sequence that joins the range tables in the list */
joinSequenceArray = JoinSequenceArray(rangeTableFragmentsList, jobQuery,
dependedJobList);
/*
* We use breadth-first search with pruning to create fragment combinations.
* For this, we first queue the root node (an empty combination), and then
* start traversing our search space.
*/
fragmentCombinationQueue = lappend(fragmentCombinationQueue, emptyList);
while (fragmentCombinationQueue != NIL)
{
List *fragmentCombination = NIL;
int32 joinSequenceIndex = 0;
uint32 tableId = 0;
List *tableFragments = NIL;
ListCell *tableFragmentCell = NULL;
int32 joiningTableId = NON_PRUNABLE_JOIN;
int32 joiningTableSequenceIndex = -1;
int32 rangeTableCount = 0;
/* pop first element from the fragment queue */
fragmentCombination = linitial(fragmentCombinationQueue);
fragmentCombinationQueue = list_delete_first(fragmentCombinationQueue);
/*
* If this combination covered all range tables in a join sequence, add
* this combination to our result set.
*/
joinSequenceIndex = list_length(fragmentCombination);
rangeTableCount = list_length(rangeTableFragmentsList);
if (joinSequenceIndex == rangeTableCount)
{
fragmentCombinationList = lappend(fragmentCombinationList,
fragmentCombination);
continue;
}
/* find the next range table to add to our search space */
tableId = joinSequenceArray[joinSequenceIndex].rangeTableId;
tableFragments = FindRangeTableFragmentsList(rangeTableFragmentsList, tableId);
/* resolve sequence index for the previous range table we join against */
joiningTableId = joinSequenceArray[joinSequenceIndex].joiningRangeTableId;
if (joiningTableId != NON_PRUNABLE_JOIN)
{
int32 sequenceIndex = 0;
for (sequenceIndex = 0; sequenceIndex < rangeTableCount; sequenceIndex++)
{
JoinSequenceNode *joinSequenceNode = &joinSequenceArray[sequenceIndex];
if (joinSequenceNode->rangeTableId == joiningTableId)
{
joiningTableSequenceIndex = sequenceIndex;
break;
}
}
Assert(joiningTableSequenceIndex != -1);
}
/*
* We walk over each range table fragment, and check if we can prune out
* this fragment joining with the existing fragment combination. If we
* can't prune away, we create a new fragment combination and add it to
* our search space.
*/
foreach(tableFragmentCell, tableFragments)
{
RangeTableFragment *tableFragment = lfirst(tableFragmentCell);
bool joinPrunable = false;
if (joiningTableId != NON_PRUNABLE_JOIN)
{
RangeTableFragment *joiningTableFragment =
list_nth(fragmentCombination, joiningTableSequenceIndex);
joinPrunable = JoinPrunable(joiningTableFragment, tableFragment);
}
/* if join can't be pruned, extend fragment combination and search */
if (!joinPrunable)
{
List *newFragmentCombination = list_copy(fragmentCombination);
newFragmentCombination = lappend(newFragmentCombination, tableFragment);
fragmentCombinationQueue = lappend(fragmentCombinationQueue,
newFragmentCombination);
}
}
}
return fragmentCombinationList;
}
/*
* JoinSequenceArray walks over the join nodes in the job query and constructs a join
* sequence containing an entry for each joined table. The function then returns an
* array of join sequence nodes, in which each node contains the id of a table in the
* range table list and the id of a preceding table with which it is joined, if any.
*/
static JoinSequenceNode *
JoinSequenceArray(List *rangeTableFragmentsList, Query *jobQuery, List *dependedJobList)
{
List *rangeTableList = jobQuery->rtable;
uint32 rangeTableCount = (uint32) list_length(rangeTableList);
uint32 sequenceNodeSize = sizeof(JoinSequenceNode);
uint32 joinedTableCount = 0;
List *joinedTableList = NIL;
List *joinExprList = NIL;
ListCell *joinExprCell = NULL;
uint32 firstRangeTableId = 1;
JoinSequenceNode *joinSequenceArray = palloc0(rangeTableCount * sequenceNodeSize);
joinExprList = JoinExprList(jobQuery->jointree);
/* pick first range table as starting table for the join sequence */
if (list_length(joinExprList) > 0)
{
JoinExpr *firstExpr = (JoinExpr *) linitial(joinExprList);
RangeTblRef *leftTableRef = (RangeTblRef *) firstExpr->larg;
firstRangeTableId = leftTableRef->rtindex;
}
else
{
/* when there are no joins, the join sequence contains a node for the table */
firstRangeTableId = 1;
}
joinSequenceArray[joinedTableCount].rangeTableId = firstRangeTableId;
joinSequenceArray[joinedTableCount].joiningRangeTableId = NON_PRUNABLE_JOIN;
joinedTableCount++;
foreach(joinExprCell, joinExprList)
{
JoinExpr *joinExpr = (JoinExpr *) lfirst(joinExprCell);
JoinType joinType = joinExpr->jointype;
RangeTblRef *rightTableRef = (RangeTblRef *) joinExpr->rarg;
JoinSequenceNode *nextJoinSequenceNode = NULL;
uint32 nextRangeTableId = rightTableRef->rtindex;
ListCell *nextJoinClauseCell = NULL;
Index existingRangeTableId = 0;
bool applyJoinPruning = false;
List *nextJoinClauseList = make_ands_implicit((Expr *) joinExpr->quals);
/*
* If next join clause list is empty, the user tried a cartesian product
* between tables. We don't support this functionality, and error out.
*/
if (nextJoinClauseList == NIL)
{
ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot perform distributed planning on this query"),
errdetail("Cartesian products are currently unsupported")));
}
/*
* We now determine if we can apply join pruning between existing range
* tables and this new one.
*/
foreach(nextJoinClauseCell, nextJoinClauseList)
{
OpExpr *nextJoinClause = (OpExpr *) lfirst(nextJoinClauseCell);
Var *leftColumn = LeftColumn(nextJoinClause);
Var *rightColumn = RightColumn(nextJoinClause);
Index leftRangeTableId = leftColumn->varno;
Index rightRangeTableId = rightColumn->varno;
bool leftPartitioned = false;
bool rightPartitioned = false;
/*
* We have a table from the existing join list joining with the next
* table. First resolve the existing table's range table id.
*/
if (leftRangeTableId == nextRangeTableId)
{
existingRangeTableId = rightRangeTableId;
}
else
{
existingRangeTableId = leftRangeTableId;
}
/*
* Then, we check if we can apply join pruning between the existing
* range table and this new one. For this, columns need to have the
* same type and be the partition column for their respective tables.
*/
if (leftColumn->vartype != rightColumn->vartype)
{
continue;
}
/*
* Check if this is a broadcast outer join, meaning the inner table has only
* 1 shard.
*
* Broadcast outer join is a special case. In a left join, we want to join
* every fragment on the left with the one fragment on the right to ensure
* that all results from the left are included. As an optimization, we could
* perform these joins with any empty set instead of an actual fragment, but
* in any case they must not be pruned.
*/
if (IS_OUTER_JOIN(joinType))
{
int innerRangeTableId = 0;
List *tableFragments = NIL;
int fragmentCount = 0;
if (joinType == JOIN_RIGHT)
{
innerRangeTableId = existingRangeTableId;
}
else
{
/*
* Note: For a full join the logical planner ensures a 1-1 mapping,
* thus it is sufficient to check one side.
*/
innerRangeTableId = nextRangeTableId;
}
tableFragments = FindRangeTableFragmentsList(rangeTableFragmentsList,
innerRangeTableId);
fragmentCount = list_length(tableFragments);
if (fragmentCount == 1)
{
continue;
}
}
leftPartitioned = PartitionedOnColumn(leftColumn, rangeTableList,
dependedJobList);
rightPartitioned = PartitionedOnColumn(rightColumn, rangeTableList,
dependedJobList);
if (leftPartitioned && rightPartitioned)
{
/* make sure this join clause references only simple columns */
CheckJoinBetweenColumns(nextJoinClause);
applyJoinPruning = true;
break;
}
}
/* set next joining range table's info in the join sequence */
nextJoinSequenceNode = &joinSequenceArray[joinedTableCount];
if (applyJoinPruning)
{
nextJoinSequenceNode->rangeTableId = nextRangeTableId;
nextJoinSequenceNode->joiningRangeTableId = (int32) existingRangeTableId;
}
else
{
nextJoinSequenceNode->rangeTableId = nextRangeTableId;
nextJoinSequenceNode->joiningRangeTableId = NON_PRUNABLE_JOIN;
}
joinedTableList = lappend_int(joinedTableList, nextRangeTableId);
joinedTableCount++;
}
return joinSequenceArray;
}
/*
* PartitionedOnColumn finds the given column's range table entry, and checks if
* that range table is partitioned on the given column.
*/
static bool
PartitionedOnColumn(Var *column, List *rangeTableList, List *dependedJobList)
{
bool partitionedOnColumn = false;
Index rangeTableId = column->varno;
RangeTblEntry *rangeTableEntry = rt_fetch(rangeTableId, rangeTableList);
CitusRTEKind rangeTableType = GetRangeTblKind(rangeTableEntry);
if (rangeTableType == CITUS_RTE_RELATION)
{
Oid relationId = rangeTableEntry->relid;
Var *partitionColumn = PartitionColumn(relationId, rangeTableId);
if (partitionColumn->varattno == column->varattno)
{
partitionedOnColumn = true;
}
}
else if (rangeTableType == CITUS_RTE_REMOTE_QUERY)
{
Job *job = JobForRangeTable(dependedJobList, rangeTableEntry);
MapMergeJob *mapMergeJob = (MapMergeJob *) job;
Var *partitionColumn = NULL;
Var *remoteRelationColumn = NULL;
TargetEntry *targetEntry = NULL;
/*
* The column's current attribute number is it's location in the target
* list for the table represented by the remote query. We retrieve this
* value from the target list to compare against the partition column
* as stored in the job.
*/
List *targetEntryList = job->jobQuery->targetList;
int32 columnIndex = column->varattno - 1;
Assert(columnIndex >= 0);
Assert(columnIndex < list_length(targetEntryList));
targetEntry = (TargetEntry *) list_nth(targetEntryList, columnIndex);
remoteRelationColumn = (Var *) targetEntry->expr;
Assert(IsA(remoteRelationColumn, Var));
/* retrieve the partition column for the job */
partitionColumn = mapMergeJob->partitionColumn;
if (partitionColumn->varattno == remoteRelationColumn->varattno)
{
partitionedOnColumn = true;
}
}
return partitionedOnColumn;
}
/* Checks that the join clause references only simple columns. */
static void
CheckJoinBetweenColumns(OpExpr *joinClause)
{
List *argumentList = joinClause->args;
Node *leftArgument = (Node *) linitial(argumentList);
Node *rightArgument = (Node *) lsecond(argumentList);
NodeTag leftArgumentType = nodeTag(leftArgument);
NodeTag rightArgumentType = nodeTag(rightArgument);
if (leftArgumentType != T_Var || rightArgumentType != T_Var)
{
ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot perform local joins that involve expressions"),
errdetail("local joins can be performed between columns only")));
}
}
/*
* FindRangeTableFragmentsList walks over the given list of range table fragments
* and, returns the one with the given table id.
*/
static List *
FindRangeTableFragmentsList(List *rangeTableFragmentsList, int tableId)
{
List *foundTableFragments = NIL;
ListCell *rangeTableFragmentsCell = NULL;
foreach(rangeTableFragmentsCell, rangeTableFragmentsList)
{
List *tableFragments = (List *) lfirst(rangeTableFragmentsCell);
if (tableFragments != NIL)
{
RangeTableFragment *tableFragment =
(RangeTableFragment *) linitial(tableFragments);
if (tableFragment->rangeTableId == tableId)
{
foundTableFragments = tableFragments;
break;
}
}
}
return foundTableFragments;
}
/*
* JoinPrunable checks if a join between the given left and right fragments can
* be pruned away, without performing the actual join. To do this, the function
* checks if we have a hash repartition join. If we do, the function determines
* pruning based on partitionIds. Else if we have a merge repartition join, the
* function checks if the two fragments have disjoint intervals.
*/
static bool
JoinPrunable(RangeTableFragment *leftFragment, RangeTableFragment *rightFragment)
{
bool joinPrunable = false;
bool overlap = false;
ShardInterval *leftFragmentInterval = NULL;
ShardInterval *rightFragmentInterval = NULL;
/*
* If both range tables are remote queries, we then have a hash repartition
* join. In that case, we can just prune away this join if left and right
* hand side fragments have the same partitionId.
*/
if (leftFragment->fragmentType == CITUS_RTE_REMOTE_QUERY &&
rightFragment->fragmentType == CITUS_RTE_REMOTE_QUERY)
{
Task *leftMergeTask = (Task *) leftFragment->fragmentReference;
Task *rightMergeTask = (Task *) rightFragment->fragmentReference;
if (leftMergeTask->partitionId != rightMergeTask->partitionId)
{
ereport(DEBUG2, (errmsg("join prunable for task partitionId %u and %u",
leftMergeTask->partitionId,
rightMergeTask->partitionId)));
return true;
}
else
{
return false;
}
}
/*
* We have a range (re)partition join. We now get shard intervals for both
* fragments, and then check if these intervals overlap.
*/
leftFragmentInterval = FragmentInterval(leftFragment);
rightFragmentInterval = FragmentInterval(rightFragment);
overlap = ShardIntervalsOverlap(leftFragmentInterval, rightFragmentInterval);
if (!overlap)
{
if (log_min_messages <= DEBUG2 || client_min_messages <= DEBUG2)
{
StringInfo leftString = FragmentIntervalString(leftFragmentInterval);
StringInfo rightString = FragmentIntervalString(rightFragmentInterval);
ereport(DEBUG2, (errmsg("join prunable for intervals %s and %s",
leftString->data, rightString->data)));
}
joinPrunable = true;
}
return joinPrunable;
}
/*
* FragmentInterval takes the given fragment, and determines the range of data
* covered by this fragment. The function then returns this range (interval).
*/
static ShardInterval *
FragmentInterval(RangeTableFragment *fragment)
{
ShardInterval *fragmentInterval = NULL;
if (fragment->fragmentType == CITUS_RTE_RELATION)
{
uint64 *shardId = (uint64 *) fragment->fragmentReference;
fragmentInterval = LoadShardInterval(*shardId);
}
else if (fragment->fragmentType == CITUS_RTE_REMOTE_QUERY)
{
Task *mergeTask = (Task *) fragment->fragmentReference;
fragmentInterval = mergeTask->shardInterval;
}
return fragmentInterval;
}
/* Checks if the given shard intervals have overlapping ranges. */
bool
ShardIntervalsOverlap(ShardInterval *firstInterval, ShardInterval *secondInterval)
{
Oid typeId = InvalidOid;
FmgrInfo *comparisonFunction = NULL;
bool nonOverlap = false;
Datum firstMin = 0;
Datum firstMax = 0;
Datum secondMin = 0;
Datum secondMax = 0;
typeId = firstInterval->valueTypeId;
comparisonFunction = GetFunctionInfo(typeId, BTREE_AM_OID, BTORDER_PROC);
firstMin = firstInterval->minValue;
firstMax = firstInterval->maxValue;
secondMin = secondInterval->minValue;
secondMax = secondInterval->maxValue;
/*
* We need to have min/max values for both intervals first. Then, we assume
* two intervals i1 = [min1, max1] and i2 = [min2, max2] do not overlap if
* (max1 < min2) or (max2 < min1). For details, please see the explanation
* on overlapping intervals at http://www.rgrjr.com/emacs/overlap.html.
*/
if (firstInterval->minValueExists && firstInterval->maxValueExists &&
secondInterval->minValueExists && secondInterval->maxValueExists)
{
Datum firstDatum = CompareCall2(comparisonFunction, firstMax, secondMin);
Datum secondDatum = CompareCall2(comparisonFunction, secondMax, firstMin);
int firstComparison = DatumGetInt32(firstDatum);
int secondComparison = DatumGetInt32(secondDatum);
if (firstComparison < 0 || secondComparison < 0)
{
nonOverlap = true;
}
}
return (!nonOverlap);
}
/*
* FragmentIntervalString takes the given fragment interval, and converts this
* interval into its string representation for use in debug messages.
*/
static StringInfo
FragmentIntervalString(ShardInterval *fragmentInterval)
{
StringInfo fragmentIntervalString = NULL;
Oid typeId = fragmentInterval->valueTypeId;
Oid outputFunctionId = InvalidOid;
bool typeVariableLength = false;
FmgrInfo *outputFunction = NULL;
char *minValueString = NULL;
char *maxValueString = NULL;
Assert(fragmentInterval->minValueExists);
Assert(fragmentInterval->maxValueExists);
outputFunction = (FmgrInfo *) palloc0(sizeof(FmgrInfo));
getTypeOutputInfo(typeId, &outputFunctionId, &typeVariableLength);
fmgr_info(outputFunctionId, outputFunction);
minValueString = OutputFunctionCall(outputFunction, fragmentInterval->minValue);
maxValueString = OutputFunctionCall(outputFunction, fragmentInterval->maxValue);
fragmentIntervalString = makeStringInfo();
appendStringInfo(fragmentIntervalString, "[%s,%s]", minValueString, maxValueString);
return fragmentIntervalString;
}
/*
* UniqueFragmentList walks over the given relation fragment list, compares
* shard ids, eliminate duplicates and returns a new fragment list of unique
* shard ids. Note that this is a helper function for subquery pushdown, and it
* is used to prevent creating multiple data fetch tasks for same shards.
*/
static List *
UniqueFragmentList(List *fragmentList)
{
List *uniqueFragmentList = NIL;
ListCell *fragmentCell = NULL;
foreach(fragmentCell, fragmentList)
{
uint64 *shardId = NULL;
bool shardIdAlreadyAdded = false;
ListCell *uniqueFragmentCell = NULL;
RangeTableFragment *fragment = (RangeTableFragment *) lfirst(fragmentCell);
Assert(fragment->fragmentType == CITUS_RTE_RELATION);
shardId = fragment->fragmentReference;
foreach(uniqueFragmentCell, uniqueFragmentList)
{
RangeTableFragment *uniqueFragment =
(RangeTableFragment *) lfirst(uniqueFragmentCell);
uint64 *uniqueShardId = uniqueFragment->fragmentReference;
if (*shardId == *uniqueShardId)
{
shardIdAlreadyAdded = true;
break;
}
}
if (!shardIdAlreadyAdded)
{
uniqueFragmentList = lappend(uniqueFragmentList, fragment);
}
}
return uniqueFragmentList;
}
/*
* DataFetchTaskList builds a data fetch task for every shard in the given shard
* list, appends these data fetch tasks into a list, and returns this list.
*/
static List *
DataFetchTaskList(uint64 jobId, uint32 taskIdIndex, List *fragmentList)
{
List *dataFetchTaskList = NIL;
ListCell *fragmentCell = NULL;
foreach(fragmentCell, fragmentList)
{
RangeTableFragment *fragment = (RangeTableFragment *) lfirst(fragmentCell);
if (fragment->fragmentType == CITUS_RTE_RELATION)
{
uint64 *shardId = fragment->fragmentReference;
StringInfo shardFetchQueryString = ShardFetchQueryString(*shardId);
Task *shardFetchTask = CreateBasicTask(jobId, taskIdIndex, SHARD_FETCH_TASK,
shardFetchQueryString->data);
shardFetchTask->shardId = (*shardId);
dataFetchTaskList = lappend(dataFetchTaskList, shardFetchTask);
taskIdIndex++;
}
else if (fragment->fragmentType == CITUS_RTE_REMOTE_QUERY)
{
Task *mergeTask = (Task *) fragment->fragmentReference;
char *undefinedQueryString = NULL;
/* create merge fetch task and have it depend on the merge task */
Task *mergeFetchTask = CreateBasicTask(jobId, taskIdIndex, MERGE_FETCH_TASK,
undefinedQueryString);
mergeFetchTask->dependedTaskList = list_make1(mergeTask);
dataFetchTaskList = lappend(dataFetchTaskList, mergeFetchTask);
taskIdIndex++;
}
}
return dataFetchTaskList;
}
/*
* ShardFetchQueryString constructs a query string to fetch the given shard from
* the shards' placements.
*/
StringInfo
ShardFetchQueryString(uint64 shardId)
{
StringInfo shardFetchQuery = NULL;
uint64 shardLength = ShardLength(shardId);
/* construct two array strings for node names and port numbers */
List *shardPlacements = FinalizedShardPlacementList(shardId);
StringInfo nodeNameArrayString = NodeNameArrayString(shardPlacements);
StringInfo nodePortArrayString = NodePortArrayString(shardPlacements);
/* check storage type to create the correct query string */
ShardInterval *shardInterval = LoadShardInterval(shardId);
char storageType = shardInterval->storageType;
char *shardTableName = NULL;
/*
* If user specified a shard alias in pg_dist_shard, error out and display a
* message explaining the limitation.
*/
char *shardAliasName = LoadShardAlias(shardInterval->relationId, shardId);
if (shardAliasName != NULL)
{
ereport(ERROR, (errmsg("cannot fetch shard " UINT64_FORMAT, shardId),
errdetail("Fetching shards with aliases is currently "
"unsupported")));
}
else
{
/* construct the shard name */
char *tableName = get_rel_name(shardInterval->relationId);
shardTableName = pstrdup(tableName);
AppendShardIdToName(&shardTableName, shardId);
}
shardFetchQuery = makeStringInfo();
if (storageType == SHARD_STORAGE_TABLE || storageType == SHARD_STORAGE_RELAY ||
storageType == SHARD_STORAGE_COLUMNAR)
{
appendStringInfo(shardFetchQuery, TABLE_FETCH_COMMAND,
shardTableName, shardLength,
nodeNameArrayString->data, nodePortArrayString->data);
}
else if (storageType == SHARD_STORAGE_FOREIGN)
{
appendStringInfo(shardFetchQuery, FOREIGN_FETCH_COMMAND,
shardTableName, shardLength,
nodeNameArrayString->data, nodePortArrayString->data);
}
return shardFetchQuery;
}
/*
* NodeNameArrayString extracts the node names from the given node list, stores
* these node names in an array, and returns the array's string representation.
*/
static StringInfo
NodeNameArrayString(List *shardPlacementList)
{
StringInfo nodeNameArrayString = NULL;
ListCell *shardPlacementCell = NULL;
uint32 nodeNameCount = (uint32) list_length(shardPlacementList);
Datum *nodeNameArray = palloc0(nodeNameCount * sizeof(Datum));
uint32 nodeNameIndex = 0;
foreach(shardPlacementCell, shardPlacementList)
{
ShardPlacement *shardPlacement = (ShardPlacement *) lfirst(shardPlacementCell);
Datum nodeName = CStringGetDatum(shardPlacement->nodeName);
nodeNameArray[nodeNameIndex] = nodeName;
nodeNameIndex++;
}
nodeNameArrayString = DatumArrayString(nodeNameArray, nodeNameCount, CSTRINGOID);
return nodeNameArrayString;
}
/*
* NodePortArrayString extracts the node ports from the given node list, stores
* these node ports in an array, and returns the array's string representation.
*/
static StringInfo
NodePortArrayString(List *shardPlacementList)
{
StringInfo nodePortArrayString = NULL;
ListCell *shardPlacementCell = NULL;
uint32 nodePortCount = (uint32) list_length(shardPlacementList);
Datum *nodePortArray = palloc0(nodePortCount * sizeof(Datum));
uint32 nodePortIndex = 0;
foreach(shardPlacementCell, shardPlacementList)
{
ShardPlacement *shardPlacement = (ShardPlacement *) lfirst(shardPlacementCell);
Datum nodePort = UInt32GetDatum(shardPlacement->nodePort);
nodePortArray[nodePortIndex] = nodePort;
nodePortIndex++;
}
nodePortArrayString = DatumArrayString(nodePortArray, nodePortCount, INT4OID);
return nodePortArrayString;
}
/* Helper function to return a datum array's external string representation. */
static StringInfo
DatumArrayString(Datum *datumArray, uint32 datumCount, Oid datumTypeId)
{
StringInfo arrayStringInfo = NULL;
FmgrInfo *arrayOutFunction = NULL;
ArrayType *arrayObject = NULL;
Datum arrayObjectDatum = 0;
Datum arrayStringDatum = 0;
char *arrayString = NULL;
int16 typeLength = 0;
bool typeByValue = false;
char typeAlignment = 0;
/* construct the array object from the given array */
get_typlenbyvalalign(datumTypeId, &typeLength, &typeByValue, &typeAlignment);
arrayObject = construct_array(datumArray, datumCount, datumTypeId,
typeLength, typeByValue, typeAlignment);
arrayObjectDatum = PointerGetDatum(arrayObject);
/* convert the array object to its string representation */
arrayOutFunction = (FmgrInfo *) palloc0(sizeof(FmgrInfo));
fmgr_info(ARRAY_OUT_FUNC_ID, arrayOutFunction);
arrayStringDatum = FunctionCall1(arrayOutFunction, arrayObjectDatum);
arrayString = DatumGetCString(arrayStringDatum);
arrayStringInfo = makeStringInfo();
appendStringInfo(arrayStringInfo, "%s", arrayString);
return arrayStringInfo;
}
/*
* CreateBasicTask creates a task, initializes fields that are common to each task,
* and returns the created task.
*/
static Task *
CreateBasicTask(uint64 jobId, uint32 taskId, TaskType taskType, char *queryString)
{
Task *task = CitusMakeNode(Task);
task->jobId = jobId;
task->taskId = taskId;
task->taskType = taskType;
task->queryString = queryString;
return task;
}
/*
* UpdateRangeTableAlias walks over each fragment in the given fragment list,
* and creates an alias that represents the fragment name to be used in the
* query. The function then updates the corresponding range table entry with
* this alias.
*/
static void
UpdateRangeTableAlias(List *rangeTableList, List *fragmentList)
{
ListCell *fragmentCell = NULL;
foreach(fragmentCell, fragmentList)
{
RangeTableFragment *fragment = (RangeTableFragment *) lfirst(fragmentCell);
Index rangeTableId = fragment->rangeTableId;
RangeTblEntry *rangeTableEntry = rt_fetch(rangeTableId, rangeTableList);
Alias *fragmentAlias = FragmentAlias(rangeTableEntry, fragment);
rangeTableEntry->alias = fragmentAlias;
}
}
/*
* FragmentAlias creates an alias structure that captures the table fragment's
* name on the worker node. Each fragment represents either a regular shard, or
* a merge task.
*/
static Alias *
FragmentAlias(RangeTblEntry *rangeTableEntry, RangeTableFragment *fragment)
{
Alias *alias = NULL;
char *aliasName = NULL;
char *schemaName = NULL;
char *fragmentName = NULL;
CitusRTEKind fragmentType = fragment->fragmentType;
if (fragmentType == CITUS_RTE_RELATION)
{
char *shardAliasName = NULL;
uint64 *shardId = fragment->fragmentReference;
Oid relationId = rangeTableEntry->relid;
char *relationName = get_rel_name(relationId);
/*
* If the table is not in the default namespace (public), we include it in
* the fragment alias.
*/
Oid schemaId = get_rel_namespace(relationId);
schemaName = get_namespace_name(schemaId);
if (strncmp(schemaName, "public", NAMEDATALEN) == 0)
{
schemaName = NULL;
}
aliasName = relationName;
/*
* If user specified a shard name in pg_dist_shard, use that name in alias.
* Otherwise, set shard name in alias to <relation_name>_<shard_id>.
*/
shardAliasName = LoadShardAlias(relationId, *shardId);
if (shardAliasName != NULL)
{
fragmentName = shardAliasName;
}
else
{
char *shardName = pstrdup(relationName);
AppendShardIdToName(&shardName, *shardId);
fragmentName = shardName;
}
}
else if (fragmentType == CITUS_RTE_REMOTE_QUERY)
{
Task *mergeTask = (Task *) fragment->fragmentReference;
uint64 jobId = mergeTask->jobId;
uint32 taskId = mergeTask->taskId;
StringInfo jobSchemaName = JobSchemaName(jobId);
StringInfo taskTableName = TaskTableName(taskId);
StringInfo aliasNameString = makeStringInfo();
appendStringInfo(aliasNameString, "%s.%s",
jobSchemaName->data, taskTableName->data);
aliasName = aliasNameString->data;
fragmentName = taskTableName->data;
schemaName = jobSchemaName->data;
}
/*
* We need to set the aliasname to relation name, as pg_get_query_def() uses
* the relation name to disambiguate column names from different tables.
*/
alias = rangeTableEntry->alias;
if (alias == NULL)
{
alias = makeNode(Alias);
alias->aliasname = aliasName;
}
ModifyRangeTblExtraData(rangeTableEntry, CITUS_RTE_SHARD,
schemaName, fragmentName, NIL);
return alias;
}
/*
* AnchorShardId walks over each fragment in the given fragment list, finds the
* fragment that corresponds to the given anchor range tableId, and returns this
* fragment's shard identifier. Note that the given tableId must correspond to a
* base relation.
*/
static uint64
AnchorShardId(List *fragmentList, uint32 anchorRangeTableId)
{
uint64 anchorShardId = INVALID_SHARD_ID;
ListCell *fragmentCell = NULL;
foreach(fragmentCell, fragmentList)
{
RangeTableFragment *fragment = (RangeTableFragment *) lfirst(fragmentCell);
if (fragment->rangeTableId == anchorRangeTableId)
{
uint64 *shardIdPointer = NULL;
Assert(fragment->fragmentType == CITUS_RTE_RELATION);
shardIdPointer = (uint64 *) fragment->fragmentReference;
anchorShardId = (*shardIdPointer);
break;
}
}
Assert(anchorShardId != INVALID_SHARD_ID);
return anchorShardId;
}
/*
* PruneSqlTaskDependencies iterates over each sql task from the given sql task
* list, and prunes away any data fetch tasks which are redundant or not needed
* for the completion of that task. Specifically the function prunes away data
* fetch tasks for the anchor shard and any merge-fetch tasks, as the task
* assignment algorithm ensures co-location of these tasks.
*/
static List *
PruneSqlTaskDependencies(List *sqlTaskList)
{
ListCell *sqlTaskCell = NULL;
foreach(sqlTaskCell, sqlTaskList)
{
Task *sqlTask = (Task *) lfirst(sqlTaskCell);
List *dependedTaskList = sqlTask->dependedTaskList;
List *prunedDependedTaskList = NIL;
ListCell *dependedTaskCell = NULL;
foreach(dependedTaskCell, dependedTaskList)
{
Task *dataFetchTask = (Task *) lfirst(dependedTaskCell);
/*
* If we have a shard fetch task for the anchor shard, or if we have
* a merge fetch task, our task assignment algorithm makes sure that
* the sql task is colocated with the anchor shard / merge task. We
* can therefore prune out this data fetch task.
*/
if (dataFetchTask->taskType == SHARD_FETCH_TASK &&
dataFetchTask->shardId != sqlTask->anchorShardId)
{
prunedDependedTaskList = lappend(prunedDependedTaskList, dataFetchTask);
}
else if (dataFetchTask->taskType == MERGE_FETCH_TASK)
{
Task *mergeTaskReference = NULL;
List *mergeFetchDependencyList = dataFetchTask->dependedTaskList;
Assert(list_length(mergeFetchDependencyList) == 1);
mergeTaskReference = (Task *) linitial(mergeFetchDependencyList);
prunedDependedTaskList = lappend(prunedDependedTaskList,
mergeTaskReference);
ereport(DEBUG2, (errmsg("pruning merge fetch taskId %d",
dataFetchTask->taskId),
errdetail("Creating dependency on merge taskId %d",
mergeTaskReference->taskId)));
}
}
sqlTask->dependedTaskList = prunedDependedTaskList;
}
return sqlTaskList;
}
/*
* MapTaskList creates a list of map tasks for the given MapMerge job. For this,
* the function walks over each filter task (sql task) in the given filter task
* list, and wraps this task with a map function call. The map function call
* repartitions the filter task's output according to MapMerge job's parameters.
*/
static List *
MapTaskList(MapMergeJob *mapMergeJob, List *filterTaskList)
{
List *mapTaskList = NIL;
Query *filterQuery = mapMergeJob->job.jobQuery;
List *rangeTableList = filterQuery->rtable;
ListCell *filterTaskCell = NULL;
Var *partitionColumn = mapMergeJob->partitionColumn;
Oid partitionColumnType = partitionColumn->vartype;
int32 partitionColumnTypeMod = partitionColumn->vartypmod;
char *partitionColumnName = NULL;
List *groupClauseList = filterQuery->groupClause;
if (groupClauseList != NIL)
{
List *targetEntryList = filterQuery->targetList;
List *groupTargetEntryList = GroupTargetEntryList(groupClauseList,
targetEntryList);
TargetEntry *groupByTargetEntry = (TargetEntry *) linitial(groupTargetEntryList);
partitionColumnName = groupByTargetEntry->resname;
}
else
{
partitionColumnName = ColumnName(partitionColumn, rangeTableList);
}
foreach(filterTaskCell, filterTaskList)
{
Task *filterTask = (Task *) lfirst(filterTaskCell);
uint64 jobId = filterTask->jobId;
uint32 taskId = filterTask->taskId;
Task *mapTask = NULL;
/* wrap repartition query string around filter query string */
StringInfo mapQueryString = makeStringInfo();
char *filterQueryString = filterTask->queryString;
char *filterQueryEscapedText = quote_literal_cstr(filterQueryString);
PartitionType partitionType = mapMergeJob->partitionType;
if (partitionType == RANGE_PARTITION_TYPE)
{
ShardInterval **intervalArray = mapMergeJob->sortedShardIntervalArray;
uint32 intervalCount = mapMergeJob->partitionCount;
ArrayType *splitPointObject = SplitPointObject(intervalArray, intervalCount);
StringInfo splitPointString = SplitPointArrayString(splitPointObject,
partitionColumnType,
partitionColumnTypeMod);
appendStringInfo(mapQueryString, RANGE_PARTITION_COMMAND, jobId, taskId,
filterQueryEscapedText, partitionColumnName,
partitionColumnType, splitPointString->data);
}
else
{
uint32 partitionCount = mapMergeJob->partitionCount;
appendStringInfo(mapQueryString, HASH_PARTITION_COMMAND, jobId, taskId,
filterQueryEscapedText, partitionColumnName,
partitionColumnType, partitionCount);
}
/* convert filter query task into map task */
mapTask = filterTask;
mapTask->queryString = mapQueryString->data;
mapTask->taskType = MAP_TASK;
mapTaskList = lappend(mapTaskList, mapTask);
}
return mapTaskList;
}
/*
* ColumnName resolves the given column's name. The given column could belong to
* a regular table or to an intermediate table formed to execute a distributed
* query.
*/
static char *
ColumnName(Var *column, List *rangeTableList)
{
char *columnName = NULL;
Index tableId = column->varno;
AttrNumber columnNumber = column->varattno;
RangeTblEntry *rangeTableEntry = rt_fetch(tableId, rangeTableList);
CitusRTEKind rangeTableKind = GetRangeTblKind(rangeTableEntry);
if (rangeTableKind == CITUS_RTE_REMOTE_QUERY)
{
Alias *referenceNames = rangeTableEntry->eref;
List *columnNameList = referenceNames->colnames;
int columnIndex = columnNumber - 1;
Value *columnValue = (Value *) list_nth(columnNameList, columnIndex);
columnName = strVal(columnValue);
}
else if (rangeTableKind == CITUS_RTE_RELATION)
{
Oid relationId = rangeTableEntry->relid;
columnName = get_attname(relationId, columnNumber);
}
Assert(columnName != NULL);
return columnName;
}
/*
* SplitPointArrayString takes the array representation of the given split point
* object, and converts this array (and array's typed elements) to their string
* representations.
*/
static StringInfo
SplitPointArrayString(ArrayType *splitPointObject, Oid columnType, int32 columnTypeMod)
{
StringInfo splitPointArrayString = NULL;
Datum splitPointDatum = PointerGetDatum(splitPointObject);
Oid outputFunctionId = InvalidOid;
bool typeVariableLength = false;
FmgrInfo *arrayOutFunction = NULL;
char *arrayOutputText = NULL;
char *arrayOutputEscapedText = NULL;
char *arrayOutTypeName = NULL;
Oid arrayOutType = get_array_type(columnType);
if (arrayOutType == InvalidOid)
{
char *columnTypeName = format_type_be(columnType);
ereport(ERROR, (errmsg("cannot range repartition table on column type %s",
columnTypeName)));
}
arrayOutFunction = (FmgrInfo *) palloc0(sizeof(FmgrInfo));
getTypeOutputInfo(arrayOutType, &outputFunctionId, &typeVariableLength);
fmgr_info(outputFunctionId, arrayOutFunction);
arrayOutputText = OutputFunctionCall(arrayOutFunction, splitPointDatum);
arrayOutputEscapedText = quote_literal_cstr(arrayOutputText);
/* add an explicit cast to array's string representation */
arrayOutTypeName = format_type_with_typemod(arrayOutType, columnTypeMod);
splitPointArrayString = makeStringInfo();
appendStringInfo(splitPointArrayString, "%s::%s",
arrayOutputEscapedText, arrayOutTypeName);
return splitPointArrayString;
}
/*
* MergeTaskList creates a list of merge tasks for the given MapMerge job. While
* doing this, the function also establishes dependencies between each merge
* task and its downstream map task dependencies by creating "map fetch" tasks.
*/
static List *
MergeTaskList(MapMergeJob *mapMergeJob, List *mapTaskList, uint32 taskIdIndex)
{
List *mergeTaskList = NIL;
uint64 jobId = mapMergeJob->job.jobId;
uint32 partitionCount = mapMergeJob->partitionCount;
uint32 partitionId = 0;
uint32 initialPartitionId = 0;
/* build column name and column type arrays (table schema) */
Query *filterQuery = mapMergeJob->job.jobQuery;
List *targetEntryList = filterQuery->targetList;
/* if all map tasks were pruned away, return NIL for merge tasks */
if (mapTaskList == NIL)
{
return NIL;
}
/*
* XXX: We currently ignore the 0th partition bucket that range partitioning
* generates. This bucket holds all values less than the minimum value or
* NULLs, both of which we can currently ignore. However, when we support
* range re-partitioned OUTER joins, we will need these rows for the
* relation whose rows are retained in the OUTER join.
*/
initialPartitionId = 0;
if (mapMergeJob->partitionType == RANGE_PARTITION_TYPE)
{
initialPartitionId = 1;
partitionCount = partitionCount + 1;
}
/* build merge tasks and their associated "map output fetch" tasks */
for (partitionId = initialPartitionId; partitionId < partitionCount; partitionId++)
{
Task *mergeTask = NULL;
List *mapOutputFetchTaskList = NIL;
ListCell *mapTaskCell = NULL;
uint32 mergeTaskId = taskIdIndex;
Query *reduceQuery = mapMergeJob->reduceQuery;
if (reduceQuery == NULL)
{
uint32 columnCount = (uint32) list_length(targetEntryList);
StringInfo columnNames = ColumnNameArrayString(columnCount, jobId);
StringInfo columnTypes = ColumnTypeArrayString(targetEntryList);
StringInfo mergeQueryString = makeStringInfo();
appendStringInfo(mergeQueryString, MERGE_FILES_INTO_TABLE_COMMAND,
jobId, taskIdIndex, columnNames->data, columnTypes->data);
/* create merge task */
mergeTask = CreateBasicTask(jobId, mergeTaskId, MERGE_TASK,
mergeQueryString->data);
}
else
{
StringInfo mergeTableQueryString =
MergeTableQueryString(taskIdIndex, targetEntryList);
StringInfo intermediateTableQueryString =
IntermediateTableQueryString(jobId, taskIdIndex, reduceQuery);
StringInfo mergeAndRunQueryString = makeStringInfo();
appendStringInfo(mergeAndRunQueryString, MERGE_FILES_AND_RUN_QUERY_COMMAND,
jobId, taskIdIndex, mergeTableQueryString->data,
intermediateTableQueryString->data);
mergeTask = CreateBasicTask(jobId, mergeTaskId, MERGE_TASK,
mergeAndRunQueryString->data);
}
mergeTask->partitionId = partitionId;
taskIdIndex++;
/* create tasks to fetch map outputs to this merge task */
foreach(mapTaskCell, mapTaskList)
{
Task *mapTask = (Task *) lfirst(mapTaskCell);
/* we need node names for the query, and we'll resolve them later */
char *undefinedQueryString = NULL;
Task *mapOutputFetchTask = CreateBasicTask(jobId, taskIdIndex,
MAP_OUTPUT_FETCH_TASK,
undefinedQueryString);
mapOutputFetchTask->partitionId = partitionId;
mapOutputFetchTask->upstreamTaskId = mergeTaskId;
mapOutputFetchTask->dependedTaskList = list_make1(mapTask);
taskIdIndex++;
mapOutputFetchTaskList = lappend(mapOutputFetchTaskList, mapOutputFetchTask);
}
/* merge task depends on completion of fetch tasks */
mergeTask->dependedTaskList = mapOutputFetchTaskList;
/* if range repartitioned, each merge task represents an interval */
if (mapMergeJob->partitionType == RANGE_PARTITION_TYPE)
{
int32 mergeTaskIntervalId = partitionId - 1;
ShardInterval **mergeTaskIntervals = mapMergeJob->sortedShardIntervalArray;
Assert(mergeTaskIntervalId >= 0);
mergeTask->shardInterval = mergeTaskIntervals[mergeTaskIntervalId];
}
mergeTaskList = lappend(mergeTaskList, mergeTask);
}
return mergeTaskList;
}
/*
* ColumnNameArrayString creates a list of column names for a merged table, and
* outputs this list of column names in their (array) string representation.
*/
static StringInfo
ColumnNameArrayString(uint32 columnCount, uint64 generatingJobId)
{
StringInfo columnNameArrayString = NULL;
Datum *columnNameArray = palloc0(columnCount * sizeof(Datum));
uint32 columnNameIndex = 0;
/* build list of intermediate column names, generated by given jobId */
List *columnNameList = DerivedColumnNameList(columnCount, generatingJobId);
ListCell *columnNameCell = NULL;
foreach(columnNameCell, columnNameList)
{
Value *columnNameValue = (Value *) lfirst(columnNameCell);
char *columnNameString = strVal(columnNameValue);
Datum columnName = CStringGetDatum(columnNameString);
columnNameArray[columnNameIndex] = columnName;
columnNameIndex++;
}
columnNameArrayString = DatumArrayString(columnNameArray, columnCount, CSTRINGOID);
return columnNameArrayString;
}
/*
* ColumnTypeArrayString resolves a list of column types for a merged table, and
* outputs this list of column types in their (array) string representation.
*/
static StringInfo
ColumnTypeArrayString(List *targetEntryList)
{
StringInfo columnTypeArrayString = NULL;
ListCell *targetEntryCell = NULL;
uint32 columnCount = (uint32) list_length(targetEntryList);
Datum *columnTypeArray = palloc0(columnCount * sizeof(Datum));
uint32 columnTypeIndex = 0;
foreach(targetEntryCell, targetEntryList)
{
TargetEntry *targetEntry = (TargetEntry *) lfirst(targetEntryCell);
Node *columnExpression = (Node *) targetEntry->expr;
Oid columnTypeId = exprType(columnExpression);
int32 columnTypeMod = exprTypmod(columnExpression);
char *columnTypeName = format_type_with_typemod(columnTypeId, columnTypeMod);
Datum columnType = CStringGetDatum(columnTypeName);
columnTypeArray[columnTypeIndex] = columnType;
columnTypeIndex++;
}
columnTypeArrayString = DatumArrayString(columnTypeArray, columnCount, CSTRINGOID);
return columnTypeArrayString;
}
/*
* AssignTaskList assigns locations to given tasks based on dependencies between
* tasks and configured task assignment policies. The function also handles the
* case where multiple SQL tasks depend on the same merge task, and makes sure
* that this group of multiple SQL tasks and the merge task are assigned to the
* same location.
*/
static List *
AssignTaskList(List *sqlTaskList)
{
List *assignedSqlTaskList = NIL;
Task *firstSqlTask = NULL;
bool hasAnchorShardId = false;
bool hasMergeTaskDependencies = false;
ListCell *sqlTaskCell = NULL;
List *primarySqlTaskList = NIL;
ListCell *primarySqlTaskCell = NULL;
List *constrainedSqlTaskList = NIL;
ListCell *constrainedSqlTaskCell = NULL;
/* no tasks to assign */
if (sqlTaskList == NIL)
{
return NIL;
}
firstSqlTask = (Task *) linitial(sqlTaskList);
if (firstSqlTask->anchorShardId != INVALID_SHARD_ID)
{
hasAnchorShardId = true;
}
/*
* If these SQL tasks don't depend on any merge tasks, we can assign each
* one independently of the other. We therefore go ahead and assign these
* SQL tasks using the "anchor shard based" assignment algorithms.
*/
hasMergeTaskDependencies = HasMergeTaskDependencies(sqlTaskList);
if (!hasMergeTaskDependencies)
{
Assert(hasAnchorShardId);
assignedSqlTaskList = AssignAnchorShardTaskList(sqlTaskList);
return assignedSqlTaskList;
}
/*
* SQL tasks can depend on merge tasks in one of two ways: (1) each SQL task
* depends on merge task(s) that no other SQL task depends upon, (2) several
* SQL tasks depend on the same merge task(s) and all need to be assigned to
* the same worker node. To handle the second case, we first pick a primary
* SQL task among those that depend on the same merge task, and assign it.
*/
foreach(sqlTaskCell, sqlTaskList)
{
Task *sqlTask = (Task *) lfirst(sqlTaskCell);
List *mergeTaskList = FindDependedMergeTaskList(sqlTask);
Task *firstMergeTask = (Task *) linitial(mergeTaskList);
if (!firstMergeTask->assignmentConstrained)
{
firstMergeTask->assignmentConstrained = true;
primarySqlTaskList = lappend(primarySqlTaskList, sqlTask);
}
}
if (hasAnchorShardId)
{
primarySqlTaskList = AssignAnchorShardTaskList(primarySqlTaskList);
}
else
{
primarySqlTaskList = AssignDualHashTaskList(primarySqlTaskList);
}
/* propagate SQL task assignments to the merge tasks we depend upon */
foreach(primarySqlTaskCell, primarySqlTaskList)
{
Task *sqlTask = (Task *) lfirst(primarySqlTaskCell);
List *mergeTaskList = FindDependedMergeTaskList(sqlTask);
ListCell *mergeTaskCell = NULL;
foreach(mergeTaskCell, mergeTaskList)
{
Task *mergeTask = (Task *) lfirst(mergeTaskCell);
Assert(mergeTask->taskPlacementList == NIL);
mergeTask->taskPlacementList = list_copy(sqlTask->taskPlacementList);
}
assignedSqlTaskList = lappend(assignedSqlTaskList, sqlTask);
}
/*
* If we had a set of SQL tasks depending on the same merge task, we only
* assigned one SQL task from that set. We call the assigned SQL task the
* primary, and note that the remaining SQL tasks are constrained by the
* primary's task assignment. We propagate the primary's task assignment in
* each set to the remaining (constrained) tasks.
*/
constrainedSqlTaskList = TaskListDifference(sqlTaskList, primarySqlTaskList);
foreach(constrainedSqlTaskCell, constrainedSqlTaskList)
{
Task *sqlTask = (Task *) lfirst(constrainedSqlTaskCell);
List *mergeTaskList = FindDependedMergeTaskList(sqlTask);
List *mergeTaskPlacementList = NIL;
ListCell *mergeTaskCell = NULL;
foreach(mergeTaskCell, mergeTaskList)
{
Task *mergeTask = (Task *) lfirst(mergeTaskCell);
/*
* If we have more than one merge task, both of them should have the
* same task placement list.
*/
mergeTaskPlacementList = mergeTask->taskPlacementList;
Assert(mergeTaskPlacementList != NIL);
ereport(DEBUG3, (errmsg("propagating assignment from merge task %d "
"to constrained sql task %d",
mergeTask->taskId, sqlTask->taskId)));
}
sqlTask->taskPlacementList = list_copy(mergeTaskPlacementList);
assignedSqlTaskList = lappend(assignedSqlTaskList, sqlTask);
}
return assignedSqlTaskList;
}
/*
* HasMergeTaskDependencies checks if sql tasks in the given sql task list have
* any dependencies on merge tasks. If they do, the function returns true.
*/
static bool
HasMergeTaskDependencies(List *sqlTaskList)
{
bool hasMergeTaskDependencies = false;
Task *sqlTask = (Task *) linitial(sqlTaskList);
List *dependedTaskList = sqlTask->dependedTaskList;
ListCell *dependedTaskCell = NULL;
foreach(dependedTaskCell, dependedTaskList)
{
Task *dependedTask = (Task *) lfirst(dependedTaskCell);
if (dependedTask->taskType == MERGE_TASK)
{
hasMergeTaskDependencies = true;
break;
}
}
return hasMergeTaskDependencies;
}
/* Return true if two tasks are equal, false otherwise. */
bool
TasksEqual(const Task *a, const Task *b)
{
Assert(CitusIsA(a, Task));
Assert(CitusIsA(b, Task));
if (a->taskType != b->taskType)
{
return false;
}
if (a->jobId != b->jobId)
{
return false;
}
if (a->taskId != b->taskId)
{
return false;
}
return true;
}
/*
* TaskListAppendUnique returns a list that contains the elements of the
* input task list and appends the input task parameter if it doesn't already
* exists the list.
*/
List *
TaskListAppendUnique(List *list, Task *task)
{
if (TaskListMember(list, task))
{
return list;
}
return lappend(list, task);
}
/*
* TaskListConcatUnique append to list1 each member of list2 that isn't
* already in list1. Whether an element is already a member of the list
* is determined via TaskListMember().
*/
List *
TaskListConcatUnique(List *list1, List *list2)
{
ListCell *taskCell = NULL;
foreach(taskCell, list2)
{
Task *currentTask = (Task *) lfirst(taskCell);
if (!TaskListMember(list1, currentTask))
{
list1 = lappend(list1, currentTask);
}
}
return list1;
}
/* Is the passed in Task a member of the list. */
bool
TaskListMember(const List *taskList, const Task *task)
{
const ListCell *taskCell = NULL;
foreach(taskCell, taskList)
{
if (TasksEqual((Task *) lfirst(taskCell), task))
{
return true;
}
}
return false;
}
/*
* TaskListDifference returns a list that contains all the tasks in taskList1
* that are not in taskList2. The returned list is freshly allocated via
* palloc(), but the cells themselves point to the same objects as the cells
* of the input lists.
*/
List *
TaskListDifference(const List *list1, const List *list2)
{
const ListCell *taskCell = NULL;
List *resultList = NIL;
if (list2 == NIL)
{
return list_copy(list1);
}
foreach(taskCell, list1)
{
if (!TaskListMember(list2, lfirst(taskCell)))
{
resultList = lappend(resultList, lfirst(taskCell));
}
}
return resultList;
}
/*
* TaskListUnion generate the union of two tasks lists. This is calculated by
* copying list1 via list_copy(), then adding to it all the members of list2
* that aren't already in list1.
*/
List *
TaskListUnion(const List *list1, const List *list2)
{
const ListCell *taskCell = NULL;
List *resultList = NIL;
resultList = list_copy(list1);
foreach(taskCell, list2)
{
if (!TaskListMember(resultList, lfirst(taskCell)))
{
resultList = lappend(resultList, lfirst(taskCell));
}
}
return resultList;
}
/*
* AssignAnchorShardTaskList assigns locations to the given tasks based on the
* configured task assignment policy. The distributed executor later sends these
* tasks to their assigned locations for remote execution.
*/
static List *
AssignAnchorShardTaskList(List *taskList)
{
List *assignedTaskList = NIL;
/* choose task assignment policy based on config value */
if (TaskAssignmentPolicy == TASK_ASSIGNMENT_GREEDY)
{
assignedTaskList = GreedyAssignTaskList(taskList);
}
else if (TaskAssignmentPolicy == TASK_ASSIGNMENT_FIRST_REPLICA)
{
assignedTaskList = FirstReplicaAssignTaskList(taskList);
}
else if (TaskAssignmentPolicy == TASK_ASSIGNMENT_ROUND_ROBIN)
{
assignedTaskList = RoundRobinAssignTaskList(taskList);
}
Assert(assignedTaskList != NIL);
return assignedTaskList;
}
/*
* GreedyAssignTaskList uses a greedy algorithm similar to Hadoop's, and assigns
* locations to the given tasks. The ideal assignment algorithm balances three
* properties: (a) determinism, (b) even load distribution, and (c) consistency
* across similar task lists. To maintain these properties, the algorithm sorts
* all its input lists.
*/
static List *
GreedyAssignTaskList(List *taskList)
{
List *assignedTaskList = NIL;
List *activeShardPlacementLists = NIL;
uint32 assignedTaskCount = 0;
uint32 taskCount = list_length(taskList);
/* get the worker node list and sort the list */
List *workerNodeList = WorkerNodeList();
workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
/*
* We first sort tasks by their anchor shard id. We then walk over each task
* in the sorted list, get the task's anchor shard id, and look up the shard
* placements (locations) for this shard id. Next, we sort the placements by
* their insertion time, and append them to a new list.
*/
taskList = SortList(taskList, CompareTasksByShardId);
activeShardPlacementLists = ActiveShardPlacementLists(taskList);
while (assignedTaskCount < taskCount)
{
ListCell *workerNodeCell = NULL;
uint32 loopStartTaskCount = assignedTaskCount;
/* walk over each node and check if we can assign a task to it */
foreach(workerNodeCell, workerNodeList)
{
WorkerNode *workerNode = (WorkerNode *) lfirst(workerNodeCell);
Task *assignedTask = GreedyAssignTask(workerNode, taskList,
activeShardPlacementLists);
if (assignedTask != NULL)
{
assignedTaskList = lappend(assignedTaskList, assignedTask);
assignedTaskCount++;
}
}
/* if we could not assign any new tasks, avoid looping forever */
if (assignedTaskCount == loopStartTaskCount)
{
uint32 remainingTaskCount = taskCount - assignedTaskCount;
ereport(ERROR, (errmsg("failed to assign %u task(s) to worker nodes",
remainingTaskCount)));
}
}
return assignedTaskList;
}
/*
* GreedyAssignTask tries to assign a task to the given worker node. To do this,
* the function walks over tasks' anchor shard ids, and finds the first set of
* nodes the shards were replicated to. If any of these replica nodes and the
* given worker node match, the corresponding task is assigned to that node. If
* not, the function goes on to search the second set of replicas and so forth.
*
* Note that this function has side-effects; when the function assigns a new
* task, it overwrites the corresponding task list pointer.
*/
static Task *
GreedyAssignTask(WorkerNode *workerNode, List *taskList, List *activeShardPlacementLists)
{
Task *assignedTask = NULL;
List *taskPlacementList = NIL;
ShardPlacement *primaryPlacement = NULL;
uint32 rotatePlacementListBy = 0;
uint32 replicaIndex = 0;
uint32 replicaCount = ShardReplicationFactor;
const char *workerName = workerNode->workerName;
const uint32 workerPort = workerNode->workerPort;
while ((assignedTask == NULL) && (replicaIndex < replicaCount))
{
/* walk over all tasks and try to assign one */
ListCell *taskCell = NULL;
ListCell *placementListCell = NULL;
forboth(taskCell, taskList, placementListCell, activeShardPlacementLists)
{
Task *task = (Task *) lfirst(taskCell);
List *placementList = (List *) lfirst(placementListCell);
ShardPlacement *placement = NULL;
uint32 placementCount = 0;
/* check if we already assigned this task */
if (task == NULL)
{
continue;
}
/* check if we have enough replicas */
placementCount = list_length(placementList);
if (placementCount <= replicaIndex)
{
continue;
}
placement = (ShardPlacement *) list_nth(placementList, replicaIndex);
if ((strncmp(placement->nodeName, workerName, WORKER_LENGTH) == 0) &&
(placement->nodePort == workerPort))
{
/* we found a task to assign to the given worker node */
assignedTask = task;
taskPlacementList = placementList;
rotatePlacementListBy = replicaIndex;
/* overwrite task list to signal that this task is assigned */
taskCell->data.ptr_value = NULL;
break;
}
}
/* go over the next set of shard replica placements */
replicaIndex++;
}
/* if we found a task placement list, rotate and assign task placements */
if (assignedTask != NULL)
{
taskPlacementList = LeftRotateList(taskPlacementList, rotatePlacementListBy);
assignedTask->taskPlacementList = taskPlacementList;
primaryPlacement = (ShardPlacement *) linitial(assignedTask->taskPlacementList);
ereport(DEBUG3, (errmsg("assigned task %u to node %s:%u", assignedTask->taskId,
primaryPlacement->nodeName,
primaryPlacement->nodePort)));
}
return assignedTask;
}
/*
* FirstReplicaAssignTaskList assigns locations to the given tasks simply by
* looking at placements for a given shard. A particular task's assignments are
* then ordered by the insertion order of the relevant placements rows. In other
* words, a task for a specific shard is simply assigned to the first replica
* for that shard. This algorithm is extremely simple and intended for use when
* a customer has placed shards carefully and wants strong guarantees about
* which shards will be used by what nodes (i.e. for stronger memory residency
* guarantees).
*/
List *
FirstReplicaAssignTaskList(List *taskList)
{
/* No additional reordering need take place for this algorithm */
List *(*reorderFunction)(Task *, List *) = NULL;
taskList = ReorderAndAssignTaskList(taskList, reorderFunction);
return taskList;
}
/*
* RoundRobinAssignTaskList uses a round-robin algorithm to assign locations to
* the given tasks. An ideal round-robin implementation requires keeping shared
* state for task assignments; and we instead approximate our implementation by
* relying on the sequentially increasing jobId. For each task, we mod its jobId
* by the number of active shard placements, and ensure that we rotate between
* these placements across subsequent queries.
*/
static List *
RoundRobinAssignTaskList(List *taskList)
{
taskList = ReorderAndAssignTaskList(taskList, RoundRobinReorder);
return taskList;
}
/*
* RoundRobinReorder implements the core of the round-robin assignment policy.
* It takes a task and placement list and rotates a copy of the placement list
* based on the task's jobId. The rotated copy is returned.
*/
static List *
RoundRobinReorder(Task *task, List *placementList)
{
uint64 jobId = task->jobId;
uint32 activePlacementCount = list_length(placementList);
uint32 roundRobinIndex = (jobId % activePlacementCount);
placementList = LeftRotateList(placementList, roundRobinIndex);
return placementList;
}
/*
* ReorderAndAssignTaskList finds the placements for a task based on its anchor
* shard id and then sorts them by insertion time. If reorderFunction is given,
* it is used to reorder the placements list in a custom fashion (for instance,
* by rotation or shuffling). Returns the task list with placements assigned.
*/
static List *
ReorderAndAssignTaskList(List *taskList, List * (*reorderFunction)(Task *, List *))
{
List *assignedTaskList = NIL;
List *activeShardPlacementLists = NIL;
ListCell *taskCell = NULL;
ListCell *placementListCell = NULL;
uint32 unAssignedTaskCount = 0;
/*
* We first sort tasks by their anchor shard id. We then sort placements for
* each anchor shard by the placement's insertion time. Note that we sort
* these lists just to make our policy more deterministic.
*/
taskList = SortList(taskList, CompareTasksByShardId);
activeShardPlacementLists = ActiveShardPlacementLists(taskList);
forboth(taskCell, taskList, placementListCell, activeShardPlacementLists)
{
Task *task = (Task *) lfirst(taskCell);
List *placementList = (List *) lfirst(placementListCell);
/* inactive placements are already filtered out */
uint32 activePlacementCount = list_length(placementList);
if (activePlacementCount > 0)
{
ShardPlacement *primaryPlacement = NULL;
if (reorderFunction != NULL)
{
placementList = reorderFunction(task, placementList);
}
task->taskPlacementList = placementList;
primaryPlacement = (ShardPlacement *) linitial(task->taskPlacementList);
ereport(DEBUG3, (errmsg("assigned task %u to node %s:%u", task->taskId,
primaryPlacement->nodeName,
primaryPlacement->nodePort)));
assignedTaskList = lappend(assignedTaskList, task);
}
else
{
unAssignedTaskCount++;
}
}
/* if we have unassigned tasks, error out */
if (unAssignedTaskCount > 0)
{
ereport(ERROR, (errmsg("failed to assign %u task(s) to worker nodes",
unAssignedTaskCount)));
}
return assignedTaskList;
}
/* Helper function to compare two tasks by their anchor shardId. */
static int
CompareTasksByShardId(const void *leftElement, const void *rightElement)
{
const Task *leftTask = *((const Task **) leftElement);
const Task *rightTask = *((const Task **) rightElement);
uint64 leftShardId = leftTask->anchorShardId;
uint64 rightShardId = rightTask->anchorShardId;
/* we compare 64-bit integers, instead of casting their difference to int */
if (leftShardId > rightShardId)
{
return 1;
}
else if (leftShardId < rightShardId)
{
return -1;
}
else
{
return 0;
}
}
/*
* ActiveShardPlacementLists finds the active shard placement list for each task in
* the given task list, sorts each shard placement list by tuple insertion time,
* and adds the sorted placement list into a new list of lists. The function also
* ensures a one-to-one mapping between each placement list in the new list of
* lists and each task in the given task list.
*/
static List *
ActiveShardPlacementLists(List *taskList)
{
List *shardPlacementLists = NIL;
ListCell *taskCell = NULL;
foreach(taskCell, taskList)
{
Task *task = (Task *) lfirst(taskCell);
uint64 anchorShardId = task->anchorShardId;
List *shardPlacementList = FinalizedShardPlacementList(anchorShardId);
/* filter out shard placements that reside in inactive nodes */
List *activeShardPlacementList = ActivePlacementList(shardPlacementList);
/* sort shard placements by their insertion time */
activeShardPlacementList = SortList(activeShardPlacementList,
CompareShardPlacements);
shardPlacementLists = lappend(shardPlacementLists, activeShardPlacementList);
}
return shardPlacementLists;
}
/*
* CompareShardPlacements compares two shard placements by their tuple oid; this
* oid reflects the tuple's insertion order into pg_dist_shard_placement.
*/
int
CompareShardPlacements(const void *leftElement, const void *rightElement)
{
const ShardPlacement *leftPlacement = *((const ShardPlacement **) leftElement);
const ShardPlacement *rightPlacement = *((const ShardPlacement **) rightElement);
Oid leftTupleOid = leftPlacement->tupleOid;
Oid rightTupleOid = rightPlacement->tupleOid;
/* tuples that are inserted earlier appear first */
int tupleOidDiff = leftTupleOid - rightTupleOid;
return tupleOidDiff;
}
/*
* ActivePlacementList walks over shard placements in the given list, and finds
* the corresponding worker node for each placement. The function then checks if
* that worker node is active, and if it is, appends the placement to a new list.
* The function last returns the new placement list.
*/
static List *
ActivePlacementList(List *placementList)
{
List *activePlacementList = NIL;
ListCell *placementCell = NULL;
foreach(placementCell, placementList)
{
ShardPlacement *placement = (ShardPlacement *) lfirst(placementCell);
bool workerNodeActive = false;
/* check if the worker node for this shard placement is active */
workerNodeActive = WorkerNodeActive(placement->nodeName, placement->nodePort);
if (workerNodeActive)
{
activePlacementList = lappend(activePlacementList, placement);
}
}
return activePlacementList;
}
/*
* LeftRotateList returns a copy of the given list that has been cyclically
* shifted to the left by the given rotation count. For this, the function
* repeatedly moves the list's first element to the end of the list, and
* then returns the newly rotated list.
*/
static List *
LeftRotateList(List *list, uint32 rotateCount)
{
List *rotatedList = list_copy(list);
uint32 rotateIndex = 0;
for (rotateIndex = 0; rotateIndex < rotateCount; rotateIndex++)
{
void *firstElement = linitial(rotatedList);
rotatedList = list_delete_first(rotatedList);
rotatedList = lappend(rotatedList, firstElement);
}
return rotatedList;
}
/*
* FindDependedMergeTaskList walks over the given task's depended task list,
* finds the merge tasks in the list, and returns those found tasks in a new
* list.
*/
static List *
FindDependedMergeTaskList(Task *sqlTask)
{
List *dependedMergeTaskList = NIL;
List *dependedTaskList = sqlTask->dependedTaskList;
ListCell *dependedTaskCell = NULL;
foreach(dependedTaskCell, dependedTaskList)
{
Task *dependedTask = (Task *) lfirst(dependedTaskCell);
if (dependedTask->taskType == MERGE_TASK)
{
dependedMergeTaskList = lappend(dependedMergeTaskList, dependedTask);
}
}
return dependedMergeTaskList;
}
/*
* AssignDualHashTaskList uses a round-robin algorithm to assign locations to
* tasks; these tasks don't have any anchor shards and instead operate on (hash
* repartitioned) merged tables.
*/
static List *
AssignDualHashTaskList(List *taskList)
{
List *assignedTaskList = NIL;
ListCell *taskCell = NULL;
Task *firstTask = (Task *) linitial(taskList);
uint64 jobId = firstTask->jobId;
uint32 assignedTaskIndex = 0;
/*
* We start assigning tasks at an index determined by the jobId. This way,
* if subsequent jobs have a small number of tasks, we won't allocate the
* tasks to the same worker repeatedly.
*/
List *workerNodeList = WorkerNodeList();
uint32 workerNodeCount = (uint32) list_length(workerNodeList);
uint32 beginningNodeIndex = jobId % workerNodeCount;
/* sort worker node list and task list for deterministic results */
workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
taskList = SortList(taskList, CompareTasksByTaskId);
foreach(taskCell, taskList)
{
Task *task = (Task *) lfirst(taskCell);
List *taskPlacementList = NIL;
ShardPlacement *primaryPlacement = NULL;
uint32 replicaIndex = 0;
for (replicaIndex = 0; replicaIndex < ShardReplicationFactor; replicaIndex++)
{
uint32 assignmentOffset = beginningNodeIndex + assignedTaskIndex +
replicaIndex;
uint32 assignmentIndex = assignmentOffset % workerNodeCount;
WorkerNode *workerNode = list_nth(workerNodeList, assignmentIndex);
ShardPlacement *taskPlacement = CitusMakeNode(ShardPlacement);
taskPlacement->nodeName = pstrdup(workerNode->workerName);
taskPlacement->nodePort = workerNode->workerPort;
taskPlacementList = lappend(taskPlacementList, taskPlacement);
}
task->taskPlacementList = taskPlacementList;
primaryPlacement = (ShardPlacement *) linitial(task->taskPlacementList);
ereport(DEBUG3, (errmsg("assigned task %u to node %s:%u", task->taskId,
primaryPlacement->nodeName,
primaryPlacement->nodePort)));
assignedTaskList = lappend(assignedTaskList, task);
assignedTaskIndex++;
}
return assignedTaskList;
}
/* Helper function to compare two tasks by their taskId. */
static int
CompareTasksByTaskId(const void *leftElement, const void *rightElement)
{
const Task *leftTask = *((const Task **) leftElement);
const Task *rightTask = *((const Task **) rightElement);
uint32 leftTaskId = leftTask->taskId;
uint32 rightTaskId = rightTask->taskId;
int taskIdDiff = leftTaskId - rightTaskId;
return taskIdDiff;
}
/*
* AssignDataFetchDependencies walks over tasks in the given sql or merge task
* list. The function then propagates worker node assignments from each sql or
* merge task to the task's data fetch dependencies.
*/
static void
AssignDataFetchDependencies(List *taskList)
{
ListCell *taskCell = NULL;
foreach(taskCell, taskList)
{
Task *task = (Task *) lfirst(taskCell);
List *dependedTaskList = task->dependedTaskList;
ListCell *dependedTaskCell = NULL;
Assert(task->taskPlacementList != NIL);
Assert(task->taskType == SQL_TASK || task->taskType == MERGE_TASK);
foreach(dependedTaskCell, dependedTaskList)
{
Task *dependedTask = (Task *) lfirst(dependedTaskCell);
if (dependedTask->taskType == SHARD_FETCH_TASK ||
dependedTask->taskType == MAP_OUTPUT_FETCH_TASK)
{
dependedTask->taskPlacementList = task->taskPlacementList;
}
}
}
}
/*
* TaskListHighestTaskId walks over tasks in the given task list, finds the task
* that has the largest taskId, and returns that taskId.
*
* Note: This function assumes that the depended taskId's are set before the
* taskId's for the given task list.
*/
static uint32
TaskListHighestTaskId(List *taskList)
{
uint32 highestTaskId = 0;
ListCell *taskCell = NULL;
foreach(taskCell, taskList)
{
Task *task = (Task *) lfirst(taskCell);
if (task->taskId > highestTaskId)
{
highestTaskId = task->taskId;
}
}
return highestTaskId;
}
/*
* MergeTableQueryString builds a query string which creates a merge task table
* within the job's schema, which should have already been created by the task
* tracker protocol.
*/
static StringInfo
MergeTableQueryString(uint32 taskIdIndex, List *targetEntryList)
{
StringInfo taskTableName = TaskTableName(taskIdIndex);
StringInfo mergeTableQueryString = makeStringInfo();
StringInfo mergeTableName = makeStringInfo();
StringInfo columnsString = makeStringInfo();
ListCell *targetEntryCell = NULL;
uint32 columnCount = 0;
uint32 columnIndex = 0;
appendStringInfo(mergeTableName, "%s%s", taskTableName->data, MERGE_TABLE_SUFFIX);
columnCount = (uint32) list_length(targetEntryList);
foreach(targetEntryCell, targetEntryList)
{
TargetEntry *targetEntry = (TargetEntry *) lfirst(targetEntryCell);
Node *columnExpression = (Node *) targetEntry->expr;
Oid columnTypeId = exprType(columnExpression);
int32 columnTypeMod = exprTypmod(columnExpression);
char *columnName = NULL;
char *columnType = NULL;
StringInfo columnNameString = makeStringInfo();
appendStringInfo(columnNameString, MERGE_COLUMN_FORMAT, columnIndex);
columnName = columnNameString->data;
columnType = format_type_with_typemod(columnTypeId, columnTypeMod);
appendStringInfo(columnsString, "%s %s", columnName, columnType);
columnIndex++;
if (columnIndex != columnCount)
{
appendStringInfo(columnsString, ", ");
}
}
appendStringInfo(mergeTableQueryString, CREATE_TABLE_COMMAND, mergeTableName->data,
columnsString->data);
return mergeTableQueryString;
}
/*
* IntermediateTableQueryString builds a query string which creates a task table
* by running reduce query on already created merge table.
*/
static StringInfo
IntermediateTableQueryString(uint64 jobId, uint32 taskIdIndex, Query *reduceQuery)
{
StringInfo taskTableName = TaskTableName(taskIdIndex);
StringInfo intermediateTableQueryString = makeStringInfo();
StringInfo mergeTableName = makeStringInfo();
StringInfo columnsString = makeStringInfo();
StringInfo taskReduceQueryString = makeStringInfo();
Query *taskReduceQuery = copyObject(reduceQuery);
RangeTblEntry *rangeTableEntry = NULL;
Alias *referenceNames = NULL;
List *columnNames = NIL;
List *rangeTableList = NIL;
ListCell *columnNameCell = NULL;
uint32 columnCount = 0;
uint32 columnIndex = 0;
columnCount = FinalTargetEntryCount(reduceQuery->targetList);
columnNames = DerivedColumnNameList(columnCount, jobId);
foreach(columnNameCell, columnNames)
{
Value *columnNameValue = (Value *) lfirst(columnNameCell);
char *columnName = strVal(columnNameValue);
appendStringInfo(columnsString, "%s", columnName);
columnIndex++;
if (columnIndex != columnCount)
{
appendStringInfo(columnsString, ", ");
}
}
appendStringInfo(mergeTableName, "%s%s", taskTableName->data, MERGE_TABLE_SUFFIX);
rangeTableList = taskReduceQuery->rtable;
rangeTableEntry = (RangeTblEntry *) linitial(rangeTableList);
referenceNames = rangeTableEntry->eref;
referenceNames->aliasname = mergeTableName->data;
rangeTableEntry->alias = rangeTableEntry->eref;
ModifyRangeTblExtraData(rangeTableEntry, GetRangeTblKind(rangeTableEntry),
NULL, mergeTableName->data, NIL);
pg_get_query_def(taskReduceQuery, taskReduceQueryString);
appendStringInfo(intermediateTableQueryString, CREATE_TABLE_AS_COMMAND,
taskTableName->data, columnsString->data,
taskReduceQueryString->data);
return intermediateTableQueryString;
}
/*
* FinalTargetEntryCount returns count of target entries in the final target
* entry list.
*/
static uint32
FinalTargetEntryCount(List *targetEntryList)
{
uint32 finalTargetEntryCount = 0;
ListCell *targetEntryCell = NULL;
foreach(targetEntryCell, targetEntryList)
{
TargetEntry *targetEntry = (TargetEntry *) lfirst(targetEntryCell);
if (!targetEntry->resjunk)
{
finalTargetEntryCount++;
}
}
return finalTargetEntryCount;
}