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Refactor WrapRteRelationIntoSubquery

pull/4358/head
Sait Talha Nisanci 2020-12-14 21:07:02 +03:00
parent 0e53aa5d3b
commit 7951273f74
5 changed files with 163 additions and 101 deletions
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218
src/backend/distributed/planner/query_colocation_checker.c
View File

@ -47,7 +47,14 @@
static RangeTblEntry * AnchorRte(Query *subquery);
static List * UnionRelationRestrictionLists(List *firstRelationList,
List *secondRelationList);
static void MakeVarAttNosSequential(List *targetList);
static List * CreateFilteredTargetListForRelation(Oid relationId,
List *requiredAttributes);
static List * CreateDummyTargetList(Oid relationId, List *requiredAttributes);
static TargetEntry * CreateTargetEntryForColumn(Form_pg_attribute attributeTuple, Index
rteIndex,
int attributeNumber, int resno);
static TargetEntry * CreateTargetEntryForNullCol(Form_pg_attribute attributeTuple, int
resno);
/*
@ -78,9 +85,7 @@ CreateColocatedJoinChecker(Query *subquery, PlannerRestrictionContext *restricti
* functions (i.e., FilterPlannerRestrictionForQuery()) rely on queries
* not relations.
*/
List *allTargetList = NIL;
anchorSubquery = WrapRteRelationIntoSubquery(anchorRangeTblEntry, NIL,
&allTargetList);
anchorSubquery = WrapRteRelationIntoSubquery(anchorRangeTblEntry, NIL);
}
else if (anchorRangeTblEntry->rtekind == RTE_SUBQUERY)
{
@ -262,13 +267,9 @@ SubqueryColocated(Query *subquery, ColocatedJoinChecker *checker)
* Note that the query returned by this function does not contain any filters or
* projections. The returned query should be used cautiosly and it is mostly
* designed for generating a stub query.
*
* allTargetList will contain all columns for the given rteRelation but for the ones
* that are not required, it will have NULL entries.
*/
Query *
WrapRteRelationIntoSubquery(RangeTblEntry *rteRelation, List *requiredAttributes,
List **allTargetList)
WrapRteRelationIntoSubquery(RangeTblEntry *rteRelation, List *requiredAttributes)
{
Query *subquery = makeNode(Query);
RangeTblRef *newRangeTableRef = makeNode(RangeTblRef);
@ -281,93 +282,150 @@ WrapRteRelationIntoSubquery(RangeTblEntry *rteRelation, List *requiredAttributes
/* set the FROM expression to the subquery */
newRangeTableRef = makeNode(RangeTblRef);
newRangeTableRef->rtindex = 1;
newRangeTableRef->rtindex = SINGLE_RTE_INDEX;
subquery->jointree = makeFromExpr(list_make1(newRangeTableRef), NULL);
Relation relation = relation_open(rteRelation->relid, AccessShareLock);
int numberOfAttributes = RelationGetNumberOfAttributes(relation);
subquery->targetList =
CreateFilteredTargetListForRelation(rteRelation->relid, requiredAttributes);
bool shouldAssignDummyNullColumn = list_length(requiredAttributes) == 0;
bool assignedDummyNullColumn = false;
int attributeNumber = 1;
int resultNo = 1;
for (; attributeNumber <= numberOfAttributes; attributeNumber++)
if (list_length(subquery->targetList) == 0)
{
Form_pg_attribute attributeTuple =
TupleDescAttr(relation->rd_att, attributeNumber - 1);
Var *targetColumn =
makeVar(newRangeTableRef->rtindex, attributeNumber, attributeTuple->atttypid,
attributeTuple->atttypmod, attributeTuple->attcollation, 0);
TargetEntry *targetEntry =
makeTargetEntry((Expr *) targetColumn, attributeNumber,
strdup(attributeTuple->attname.data), false);
if (shouldAssignDummyNullColumn && !assignedDummyNullColumn)
{
/*
* in case there is no required column, we assign one dummy NULL target entry
* to the subquery targetList so that it has at least one target.
* (targetlist should have at least one element)
*/
subquery->targetList = lappend(subquery->targetList, targetEntry);
assignedDummyNullColumn = true;
}
if (!list_member_int(requiredAttributes, attributeNumber))
{
/*
* We add a null target entry because we don't have an easy
* way of changing all the references to this column and
* we don't want to break postgres query.
*/
targetEntry->expr =
(Expr *) makeNullConst(attributeTuple->atttypid,
attributeTuple->atttypmod,
attributeTuple->attcollation);
*allTargetList = lappend(*allTargetList, targetEntry);
}
else
{
TargetEntry *copyTargetEntry = copyObject(targetEntry);
*allTargetList = lappend(*allTargetList, copyTargetEntry);
/* In the subquery with only required attribute numbers, the result no
* corresponds to the ordinal index of it in targetList.
*/
targetEntry->resno = resultNo++;
subquery->targetList = lappend(subquery->targetList, targetEntry);
}
/*
* in case there is no required column, we assign one dummy NULL target entry
* to the subquery targetList so that it has at least one target.
* (targetlist should have at least one element)
*/
subquery->targetList = CreateDummyTargetList(rteRelation->relid,
requiredAttributes);
}
MakeVarAttNosSequential(*allTargetList);
relation_close(relation, NoLock);
return subquery;
}
/*
* MakeVarAttNosSequential changes the attribute numbers of the given targetList
* to sequential numbers, [1, 2, 3] ...
* CreateAllTargetListForRelation creates a target list which contains all the columns
* of the given relation. If the column is not in required columns, then it is added
* as a NULL column.
*/
static void
MakeVarAttNosSequential(List *targetList)
List *
CreateAllTargetListForRelation(Oid relationId, List *requiredAttributes)
{
TargetEntry *entry = NULL;
int attrNo = 1;
foreach_ptr(entry, targetList)
{
if (IsA(entry->expr, Var))
{
Var *var = (Var *) entry->expr;
Relation relation = relation_open(relationId, AccessShareLock);
int numberOfAttributes = RelationGetNumberOfAttributes(relation);
/*
* the inner subquery is an intermediate result hence
* the attribute no's should be in ordinal order. [1, 2, 3...]
*/
var->varattno = attrNo++;
List *targetList = NIL;
int varAttrNo = 1;
for (int attrNum = 1; attrNum <= numberOfAttributes; attrNum++)
{
Form_pg_attribute attributeTuple =
TupleDescAttr(relation->rd_att, attrNum - 1);
int resNo = attrNum;
if (!list_member_int(requiredAttributes, attrNum))
{
TargetEntry *nullTargetEntry =
CreateTargetEntryForNullCol(attributeTuple, resNo);
targetList = lappend(targetList, nullTargetEntry);
}
else
{
TargetEntry *targetEntry =
CreateTargetEntryForColumn(attributeTuple, SINGLE_RTE_INDEX, varAttrNo++,
resNo);
targetList = lappend(targetList, targetEntry);
}
}
relation_close(relation, NoLock);
return targetList;
}
/*
* CreateFilteredTargetListForRelation creates a target list which contains
* only the required columns of the given relation. If there is not required
* columns then a dummy NULL column is put as the only entry.
*/
static List *
CreateFilteredTargetListForRelation(Oid relationId, List *requiredAttributes)
{
Relation relation = relation_open(relationId, AccessShareLock);
int numberOfAttributes = RelationGetNumberOfAttributes(relation);
List *targetList = NIL;
int resultNo = 1;
for (int attrNum = 1; attrNum <= numberOfAttributes; attrNum++)
{
Form_pg_attribute attributeTuple =
TupleDescAttr(relation->rd_att, attrNum - 1);
if (list_member_int(requiredAttributes, attrNum))
{
/* In the subquery with only required attribute numbers, the result no
* corresponds to the ordinal index of it in targetList.
*/
TargetEntry *targetEntry =
CreateTargetEntryForColumn(attributeTuple, SINGLE_RTE_INDEX, attrNum,
resultNo++);
targetList = lappend(targetList, targetEntry);
}
}
relation_close(relation, NoLock);
return targetList;
}
/*
* CreateDummyTargetList creates a target list which contains only a
* NULL entry.
*/
static List *
CreateDummyTargetList(Oid relationId, List *requiredAttributes)
{
Relation relation = relation_open(relationId, AccessShareLock);
Form_pg_attribute attributeTuple =
TupleDescAttr(relation->rd_att, 0);
TargetEntry *nullTargetEntry =
CreateTargetEntryForNullCol(attributeTuple, 1);
relation_close(relation, NoLock);
return list_make1(nullTargetEntry);
}
/*
* CreateTargetEntryForColumn creates a target entry for the given
* column.
*/
static TargetEntry *
CreateTargetEntryForColumn(Form_pg_attribute attributeTuple, Index rteIndex,
int attributeNumber, int resno)
{
Var *targetColumn =
makeVar(rteIndex, attributeNumber, attributeTuple->atttypid,
attributeTuple->atttypmod, attributeTuple->attcollation, 0);
TargetEntry *targetEntry =
makeTargetEntry((Expr *) targetColumn, resno,
strdup(attributeTuple->attname.data), false);
return targetEntry;
}
/*
* CreateTargetEntryForNullCol creates a target entry that has a NULL expression.
*/
static TargetEntry *
CreateTargetEntryForNullCol(Form_pg_attribute attributeTuple, int resno)
{
Expr *nullExpr = (Expr *) makeNullConst(attributeTuple->atttypid,
attributeTuple->atttypmod,
attributeTuple->attcollation);
TargetEntry *targetEntry =
makeTargetEntry(nullExpr, resno,
strdup(attributeTuple->attname.data), false);
return targetEntry;
}

7
src/backend/distributed/planner/recursive_planning.c
View File

@ -1403,9 +1403,10 @@ ReplaceRTERelationWithRteSubquery(RangeTblEntry *rangeTableEntry,
List *requiredAttrNumbers,
RecursivePlanningContext *context)
{
List *outerQueryTargetList = NIL;
Query *subquery = WrapRteRelationIntoSubquery(rangeTableEntry, requiredAttrNumbers,
&outerQueryTargetList);
Query *subquery = WrapRteRelationIntoSubquery(rangeTableEntry, requiredAttrNumbers);
List *outerQueryTargetList = CreateAllTargetListForRelation(rangeTableEntry->relid,
requiredAttrNumbers);
List *restrictionList =
GetRestrictInfoListForRelation(rangeTableEntry,
context->plannerRestrictionContext);

5
src/include/distributed/query_colocation_checker.h
View File

@ -35,8 +35,7 @@ extern ColocatedJoinChecker CreateColocatedJoinChecker(Query *subquery,
restrictionContext);
extern bool SubqueryColocated(Query *subquery, ColocatedJoinChecker *context);
extern Query * WrapRteRelationIntoSubquery(RangeTblEntry *rteRelation,
List *requiredAttributes,
List **allTargetList);
List *requiredAttributes);
extern List * CreateAllTargetListForRelation(Oid relationId, List *requiredAttributes);
#endif /* QUERY_COLOCATION_CHECKER_H */

12
src/test/regress/expected/local_dist_join_mixed.out
View File

@ -665,16 +665,20 @@ select (SELECT local.id) FROM local, distributed WHERE distributed.id != 1 LIMIT
DEBUG: Wrapping relation "local" to a subquery
DEBUG: generating subplan XXX_1 for subquery SELECT id FROM local_dist_join_mixed.local WHERE true
DEBUG: Plan XXX query after replacing subqueries and CTEs: SELECT (SELECT local.id) AS id FROM (SELECT local_1.id, NULL::text AS title FROM (SELECT intermediate_result.id FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(id bigint)) local_1) local, local_dist_join_mixed.distributed WHERE (distributed.id OPERATOR(pg_catalog.<>) 1) LIMIT 1
ERROR: could not run distributed query with subquery outside the FROM, WHERE and HAVING clauses
HINT: Consider using an equality filter on the distributed table's partition column.
DEBUG: push down of limit count: 1
id
---------------------------------------------------------------------
0
(1 row)
-- currently not supported, but should work with https://github.com/citusdata/citus/pull/4360/files
SELECT
name, (SELECT id FROM local WHERE id = e.id)
FROM
distributed e
ORDER BY 1,2 LIMIT 1;
ERROR: could not run distributed query with subquery outside the FROM, WHERE and HAVING clauses
HINT: Consider using an equality filter on the distributed table's partition column.
ERROR: direct joins between distributed and local tables are not supported
HINT: Use CTE's or subqueries to select from local tables and use them in joins
-- set operations
SELECT local.* FROM distributed JOIN local USING (id)
EXCEPT