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Fix locking in create_distributed_table

pull/1503/head
Marco Slot 2017-08-10 17:58:44 +03:00 committed by velioglu
parent 7c65001e23
commit 53584affa8
2 changed files with 28 additions and 10 deletions
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29
src/backend/distributed/commands/create_distributed_table.c
View File

@ -311,14 +311,6 @@ CreateDistributedTable(Oid relationId, Var *distributionColumn, char distributio
/* we need to calculate these variables before creating distributed metadata */
localTableEmpty = LocalTableEmpty(relationId);
colocatedTableId = ColocatedTableId(colocationId);
if (colocatedTableId != InvalidOid)
{
/*
* We take lock on colocatedTableId, because we want to ensure that colocated
* table is not dropped until we create all colocated shards.
*/
colocatedRelation = relation_open(colocatedTableId, AccessShareLock);
}
/* create an entry for distributed table in pg_dist_partition */
InsertIntoPgDistPartition(relationId, distributionMethod, distributionColumn,
@ -530,6 +522,7 @@ ColocationIdForNewTable(Oid relationId, Var *distributionColumn,
Relation pgDistColocation = heap_open(DistColocationRelationId(), ExclusiveLock);
Oid distributionColumnType = distributionColumn->vartype;
bool createdColocationGroup = false;
if (pg_strncasecmp(colocateWithTableName, "default", NAMEDATALEN) == 0)
{
@ -541,11 +534,14 @@ ColocationIdForNewTable(Oid relationId, Var *distributionColumn,
{
colocationId = CreateColocationGroup(ShardCount, ShardReplicationFactor,
distributionColumnType);
createdColocationGroup = true;
}
}
else if (pg_strncasecmp(colocateWithTableName, "none", NAMEDATALEN) == 0)
{
colocationId = GetNextColocationId();
createdColocationGroup = true;
}
else
{
@ -558,7 +554,22 @@ ColocationIdForNewTable(Oid relationId, Var *distributionColumn,
colocationId = TableColocationId(sourceRelationId);
}
heap_close(pgDistColocation, NoLock);
/*
* If we created a new colocation group then we need to keep the lock to
* prevent a concurrent create_distributed_table call from creating another
* colocation group with the same parameters. If we're using an existing
* colocation group then other transactions will use the same one.
*/
if (createdColocationGroup)
{
/* keep the exclusive lock */
heap_close(pgDistColocation, NoLock);
}
else
{
/* release the exclusive lock */
heap_close(pgDistColocation, ExclusiveLock);
}
}
return colocationId;

9
src/backend/distributed/utils/colocation_utils.c
View File

@ -31,6 +31,7 @@
#include "distributed/shardinterval_utils.h"
#include "distributed/worker_protocol.h"
#include "distributed/worker_transaction.h"
#include "storage/lmgr.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
@ -929,6 +930,9 @@ ColocatedShardIntervalList(ShardInterval *shardInterval)
/*
* ColocatedTableId returns an arbitrary table which belongs to given colocation
* group. If there is not such a colocation group, it returns invalid oid.
*
* This function also takes an AccessShareLock on the co-colocated table to
* guarantee that the table isn't dropped for the remainder of the transaction.
*/
Oid
ColocatedTableId(Oid colocationId)
@ -955,7 +959,7 @@ ColocatedTableId(Oid colocationId)
ScanKeyInit(&scanKey[0], Anum_pg_dist_partition_colocationid,
BTEqualStrategyNumber, F_INT4EQ, ObjectIdGetDatum(colocationId));
/* prevent DELETE statements */
/* do not allow any tables to be dropped while we read from pg_dist_partition */
pgDistPartition = heap_open(DistPartitionRelationId(), ShareLock);
tupleDescriptor = RelationGetDescr(pgDistPartition);
scanDescriptor = systable_beginscan(pgDistPartition,
@ -967,6 +971,9 @@ ColocatedTableId(Oid colocationId)
{
colocatedTableId = heap_getattr(heapTuple, Anum_pg_dist_partition_logicalrelid,
tupleDescriptor, &isNull);
/* make sure the table isn't dropped for the remainder of the transaction */
LockRelationOid(colocatedTableId, AccessShareLock);
}
systable_endscan(scanDescriptor);