mirror of https://github.com/citusdata/citus.git
Add comments for the functions
Sameer Awasekar
parent
5a5505db55
commit
b4f8226f96
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@ -63,10 +63,6 @@ static void CreateAndCopySplitShardsForShardGroup(
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static void CreateSplitShardsForShardGroup(HTAB *mapOfShardToPlacementCreatedByWorkflow,
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List *shardGroupSplitIntervalListList,
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List *workersForPlacementList);
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static void CreateSplitShardsForShardGroupTwo(WorkerNode *sourceShardNode,
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List *sourceColocatedShardIntervalList,
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List *shardGroupSplitIntervalListList,
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List *workersForPlacementList);
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static void CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
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List *shardGroupSplitIntervalListList,
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WorkerNode *sourceWorkerNode,
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@ -113,7 +109,7 @@ static StringInfo CreateSplitShardReplicationSetupUDF(
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List *destinationWorkerNodesList);
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static void AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval);
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static void DropDummyShards(void);
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void TryDropShard(MultiConnection *connection, ShardInterval *shardInterval);
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static void TryDroppingShard(MultiConnection *connection, ShardInterval *shardInterval);
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char * CreateTemplateReplicationSlotAndReturnSnapshot(ShardInterval *shardInterval,
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WorkerNode *sourceWorkerNode,
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MultiConnection **
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@ -123,6 +119,7 @@ static List * ExecuteSplitShardReplicationSetupUDF(WorkerNode *sourceWorkerNode,
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List *sourceColocatedShardIntervalList,
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List *shardGroupSplitIntervalListList,
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List *destinationWorkerNodesList);
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static List * ParseReplicationSlotInfoFromResult(PGresult *result);
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/* Customize error message strings based on operation type */
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static const char *const SplitOperationName[] =
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@ -1400,39 +1397,28 @@ NonBlockingShardSplit(SplitOperation splitOperation,
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}
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/* Create ShardGroup split children on a list of corresponding workers. */
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static void
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CreateSplitShardsForShardGroupTwo(WorkerNode *sourceShardNode,
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List *sourceColocatedShardIntervalList,
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List *shardGroupSplitIntervalListList,
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List *workersForPlacementList)
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{
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/* Iterate on shard interval list for shard group */
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List *shardIntervalList = NULL;
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foreach_ptr(shardIntervalList, shardGroupSplitIntervalListList)
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{
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/* Iterate on split shard interval list and corresponding placement worker */
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ShardInterval *shardInterval = NULL;
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WorkerNode *workerPlacementNode = NULL;
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forboth_ptr(shardInterval, shardIntervalList, workerPlacementNode,
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workersForPlacementList)
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{
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/* Populate list of commands necessary to create shard interval on destination */
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List *splitShardCreationCommandList = GetPreLoadTableCreationCommands(
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shardInterval->relationId,
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false, /* includeSequenceDefaults */
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NULL /* auto add columnar options for cstore tables */);
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splitShardCreationCommandList = WorkerApplyShardDDLCommandList(
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splitShardCreationCommandList,
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shardInterval->shardId);
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/* Create new split child shard on the specified worker node */
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CreateObjectOnPlacement(splitShardCreationCommandList, workerPlacementNode);
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}
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}
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}
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/*
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* Given we are using PG logical replication infrastructure there are some constraints
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* that need to met around matching table names in source and target nodes:
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* The restrictions in context of split are:
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* Constraint 1: Dummy source shard(s) from shard group must exist on all destination nodes.
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* Constraint 2: Dummy target shards from shard group must exist on source node.
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* Example :
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* Shard1[1-200] is co-located with Shard2[1-200] in Worker0.
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* We are splitting 2-way to worker0 (same node) and worker1 (different node).
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*
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* Non-Dummy shards (expected from Split):
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* In Worker0 --> Shard1_1 and Shard2_1.
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* In Worker1 --> Shard1_2 and Shard2_2.
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*
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* Dummy shards:
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* From constraint 1, we need to create: Dummy Shard1 and Shard2 in Worker0. Dummy Shard1 and Shard2 in Worker1
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* Note 1 : Given there is an overlap of source and destination in Worker0, Shard1 and Shard2 need not be created.
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* Be very careful here, dropping Shard1, Shard2 with customer data to create dummy Shard1, Shard2 on worker0 is catastrophic.
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*
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* From constraint 2, we need to create: Dummy Shard1_1, Shard2_1, Shard1_2 and Shard2_2 in Worker0.
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* Note 2 : Given there is an overlap of source and destination in Worker0, Shard1_1 and Shard2_1 need not be created.
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*/
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static void
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CreateDummyShardsForShardGroup(List *sourceColocatedShardIntervalList,
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List *shardGroupSplitIntervalListList,
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@ -1546,89 +1532,13 @@ CreateWorkerForPlacementSet(List *workersForPlacementList)
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}
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static void
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AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval)
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{
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NodeShardMappingKey key;
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key.nodeId = targetNodeId;
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key.tableOwnerId = TableOwnerOid(shardInterval->relationId);
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bool found = false;
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NodeShardMappingEntry *nodeMappingEntry =
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(NodeShardMappingEntry *) hash_search(DummyShardInfoHashMap, &key, HASH_ENTER,
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&found);
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if (!found)
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{
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nodeMappingEntry->shardSplitInfoList = NIL;
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}
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nodeMappingEntry->shardSplitInfoList =
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lappend(nodeMappingEntry->shardSplitInfoList, (ShardInterval *) shardInterval);
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}
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static void
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DropDummyShards()
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{
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/* Return if no dummy shards are created */
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if (DummyShardInfoHashMap == NULL)
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{
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return;
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}
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HASH_SEQ_STATUS status;
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hash_seq_init(&status, DummyShardInfoHashMap);
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NodeShardMappingEntry *entry = NULL;
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while ((entry = (NodeShardMappingEntry *) hash_seq_search(&status)) != NULL)
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{
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uint32 nodeId = entry->key.nodeId;
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WorkerNode *shardToBeDroppedNode = FindNodeWithNodeId(nodeId,
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false /* missingOk */);
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int connectionFlags = FOR_DDL;
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connectionFlags |= OUTSIDE_TRANSACTION;
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connectionFlags |= FORCE_NEW_CONNECTION;
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MultiConnection *connection = GetNodeUserDatabaseConnection(
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connectionFlags,
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shardToBeDroppedNode->workerName,
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shardToBeDroppedNode->workerPort,
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CurrentUserName(),
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NULL /* databaseName */);
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List *dummyShardIntervalList = entry->shardSplitInfoList;
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ShardInterval *shardInterval = NULL;
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foreach_ptr(shardInterval, dummyShardIntervalList)
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{
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TryDropShard(connection, shardInterval);
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}
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CloseConnection(connection);
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}
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}
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void
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TryDropShard(MultiConnection *connection, ShardInterval *shardInterval)
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{
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char *qualifiedShardName = ConstructQualifiedShardName(shardInterval);
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StringInfo dropShardQuery = makeStringInfo();
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/* Caller enforces that foreign tables cannot be split (use DROP_REGULAR_TABLE_COMMAND) */
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appendStringInfo(dropShardQuery, DROP_REGULAR_TABLE_COMMAND,
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qualifiedShardName);
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/*
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* Perform a drop in best effort manner.
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* The shard may or may not exist and the connection could have died.
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* CreateTemplateReplicationSlotAndReturnSnapshot creates a replication slot
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* and returns its snapshot. This slot acts as a 'Template' for creating
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* replication slot copies used for logical replication.
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*
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* The snapshot remains valid till the lifetime of the session that creates it.
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*/
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ExecuteOptionalRemoteCommand(
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connection,
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dropShardQuery->data,
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NULL /* pgResult */);
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}
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char *
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CreateTemplateReplicationSlotAndReturnSnapshot(ShardInterval *shardInterval,
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WorkerNode *sourceWorkerNode,
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@ -1646,17 +1556,25 @@ CreateTemplateReplicationSlotAndReturnSnapshot(ShardInterval *shardInterval,
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CitusExtensionOwnerName(),
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get_database_name(
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MyDatabaseId));
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ClaimConnectionExclusively(sourceConnection);
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/*
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* Try to drop leftover template replication slot if any from previous operation
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* and create new one.
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*/
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char *snapShotName = DropExistingIfAnyAndCreateTemplateReplicationSlot(shardInterval,
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sourceConnection);
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*templateSlotConnection = sourceConnection;
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return snapShotName;
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}
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/*
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* ExecuteSplitShardReplicationSetupUDF executes
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* 'worker_split_shard_replication_setup' UDF on source shard node
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* and returns list of ReplicationSlotInfo.
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*/
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static List *
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ExecuteSplitShardReplicationSetupUDF(WorkerNode *sourceWorkerNode,
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List *sourceColocatedShardIntervalList,
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@ -1668,6 +1586,7 @@ ExecuteSplitShardReplicationSetupUDF(WorkerNode *sourceWorkerNode,
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shardGroupSplitIntervalListList,
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destinationWorkerNodesList);
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/* Force a new connection to execute the UDF */
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int connectionFlags = FORCE_NEW_CONNECTION;
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MultiConnection *sourceConnection = GetNodeUserDatabaseConnection(connectionFlags,
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sourceWorkerNode->
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@ -1784,3 +1703,132 @@ CreateSplitShardReplicationSetupUDF(List *sourceColocatedShardIntervalList,
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return splitShardReplicationUDF;
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}
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/*
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* ParseReplicationSlotInfoFromResult parses custom datatype 'replication_slot_info'.
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* 'replication_slot_info' is a tuple with below format:
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* <targetNodeId, tableOwnerName, replicationSlotName>
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*/
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static List *
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ParseReplicationSlotInfoFromResult(PGresult *result)
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{
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int64 rowCount = PQntuples(result);
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int64 colCount = PQnfields(result);
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List *replicationSlotInfoList = NIL;
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for (int64 rowIndex = 0; rowIndex < rowCount; rowIndex++)
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{
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ReplicationSlotInfo *replicationSlotInfo = (ReplicationSlotInfo *) palloc0(
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sizeof(ReplicationSlotInfo));
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char *targeNodeIdString = PQgetvalue(result, rowIndex, 0 /* nodeId column*/);
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replicationSlotInfo->targetNodeId = strtoul(targeNodeIdString, NULL, 10);
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/* We're using the pstrdup to copy the data into the current memory context */
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replicationSlotInfo->tableOwnerName = pstrdup(PQgetvalue(result, rowIndex,
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1 /* table owner name column */));
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/* Replication slot name */
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replicationSlotInfo->slotName = pstrdup(PQgetvalue(result, rowIndex,
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2 /* slot name column */));
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replicationSlotInfoList = lappend(replicationSlotInfoList, replicationSlotInfo);
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}
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return replicationSlotInfoList;
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}
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/*
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* AddDummyShardEntryInMap adds shard entry into hash map to keep track
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* of dummy shards that are created. These shards are cleanedup after split completes.
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*
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* This is a cautious measure to keep track of dummy shards created for constraints
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* of logical replication. We cautiously delete only the dummy shards added in the DummyShardHashMap.
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*/
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static void
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AddDummyShardEntryInMap(uint32 targetNodeId, ShardInterval *shardInterval)
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{
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NodeShardMappingKey key;
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key.nodeId = targetNodeId;
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key.tableOwnerId = TableOwnerOid(shardInterval->relationId);
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bool found = false;
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NodeShardMappingEntry *nodeMappingEntry =
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(NodeShardMappingEntry *) hash_search(DummyShardInfoHashMap, &key, HASH_ENTER,
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&found);
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if (!found)
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{
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nodeMappingEntry->shardSplitInfoList = NIL;
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}
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nodeMappingEntry->shardSplitInfoList =
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lappend(nodeMappingEntry->shardSplitInfoList, (ShardInterval *) shardInterval);
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}
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static void
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DropDummyShards()
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{
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/* Return if no dummy shards are created */
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if (DummyShardInfoHashMap == NULL)
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{
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return;
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}
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HASH_SEQ_STATUS status;
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hash_seq_init(&status, DummyShardInfoHashMap);
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NodeShardMappingEntry *entry = NULL;
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while ((entry = (NodeShardMappingEntry *) hash_seq_search(&status)) != NULL)
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{
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uint32 nodeId = entry->key.nodeId;
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WorkerNode *shardToBeDroppedNode = FindNodeWithNodeId(nodeId,
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false /* missingOk */);
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int connectionFlags = FOR_DDL;
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connectionFlags |= OUTSIDE_TRANSACTION;
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connectionFlags |= FORCE_NEW_CONNECTION;
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MultiConnection *connection = GetNodeUserDatabaseConnection(
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connectionFlags,
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shardToBeDroppedNode->workerName,
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shardToBeDroppedNode->workerPort,
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CurrentUserName(),
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NULL /* databaseName */);
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List *dummyShardIntervalList = entry->shardSplitInfoList;
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ShardInterval *shardInterval = NULL;
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foreach_ptr(shardInterval, dummyShardIntervalList)
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{
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TryDroppingShard(connection, shardInterval);
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}
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CloseConnection(connection);
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}
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}
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/*
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* TryDroppingShard drops a given shard on the source node connection.
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*/
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static void
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TryDroppingShard(MultiConnection *connection, ShardInterval *shardInterval)
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{
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char *qualifiedShardName = ConstructQualifiedShardName(shardInterval);
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StringInfo dropShardQuery = makeStringInfo();
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/* Caller enforces that foreign tables cannot be split (use DROP_REGULAR_TABLE_COMMAND) */
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appendStringInfo(dropShardQuery, DROP_REGULAR_TABLE_COMMAND,
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qualifiedShardName);
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/*
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* Perform a drop in best effort manner.
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* The shard may or may not exist and the connection could have died.
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*/
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ExecuteOptionalRemoteCommand(
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connection,
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dropShardQuery->data,
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NULL /* pgResult */);
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}
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@ -517,42 +517,6 @@ CreateReplicationSlots(MultiConnection *sourceNodeConnection, char *templateSlot
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}
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/*
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* ParseReplicationSlotInfoFromResult parses custom datatype 'replication_slot_info'.
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* 'replication_slot_info' is a tuple with below format:
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* <targetNodeId, tableOwnerName, replicationSlotName>
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*/
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List *
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ParseReplicationSlotInfoFromResult(PGresult *result)
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{
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int64 rowCount = PQntuples(result);
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int64 colCount = PQnfields(result);
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List *replicationSlotInfoList = NIL;
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for (int64 rowIndex = 0; rowIndex < rowCount; rowIndex++)
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{
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ReplicationSlotInfo *replicationSlotInfo = (ReplicationSlotInfo *) palloc0(
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sizeof(ReplicationSlotInfo));
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char *targeNodeIdString = PQgetvalue(result, rowIndex, 0 /* nodeId column*/);
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replicationSlotInfo->targetNodeId = strtoul(targeNodeIdString, NULL, 10);
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/* We're using the pstrdup to copy the data into the current memory context */
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replicationSlotInfo->tableOwnerName = pstrdup(PQgetvalue(result, rowIndex,
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1 /* table owner name column */));
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/* Replication slot name */
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replicationSlotInfo->slotName = pstrdup(PQgetvalue(result, rowIndex,
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2 /* slot name column */));
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replicationSlotInfoList = lappend(replicationSlotInfoList, replicationSlotInfo);
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}
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return replicationSlotInfoList;
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}
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/*
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* DropAllShardSplitLeftOvers drops shard split subscriptions, publications, roles
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* and replication slots. These might have been left there after
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@ -61,7 +61,6 @@ extern int NodeShardMappingHashCompare(const void *left, const void *right, Size
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extern HTAB * SetupHashMapForShardInfo(void);
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/* Functions for subscriber metadata management */
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extern List * ParseReplicationSlotInfoFromResult(PGresult *result);
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extern List * PopulateShardSplitSubscriptionsMetadataList(HTAB *shardSplitInfoHashMap,
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List *replicationSlotInfoList);
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extern HTAB * CreateShardSplitInfoMapForPublication(
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@ -73,7 +72,7 @@ extern HTAB * CreateShardSplitInfoMapForPublication(
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extern void CreateShardSplitPublications(MultiConnection *sourceConnection,
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HTAB *shardInfoHashMapForPublication);
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extern void CreateShardSplitSubscriptions(List *targetNodeConnectionList,
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List *shardSplitPubSubMetadataList,
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List *shardSplitSubscriberMetadataList,
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WorkerNode *sourceWorkerNode, char *superUser,
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char *databaseName);
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extern void CreateReplicationSlots(MultiConnection *sourceNodeConnection,
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