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Acquire AccessShareLock before updating table statistics (#5155)

pull/5175/head
Naisila Puka 2021-08-12 13:58:15 +03:00 committed by GitHub
parent 6bb4c5e94f
commit e5b32b2c3c
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5 changed files with 192 additions and 6 deletions
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21
src/backend/distributed/metadata/metadata_utility.c
View File

@ -893,11 +893,22 @@ GenerateAllShardStatisticsQueryForNode(WorkerNode *workerNode, List *citusTableI
Oid relationId = InvalidOid;
foreach_oid(relationId, citusTableIds)
{
List *shardIntervalsOnNode = ShardIntervalsOnWorkerGroup(workerNode, relationId);
char *shardStatisticsQuery =
GenerateShardStatisticsQueryForShardList(shardIntervalsOnNode,
useShardMinMaxQuery);
appendStringInfoString(allShardStatisticsQuery, shardStatisticsQuery);
/*
* Ensure the table still exists by trying to acquire a lock on it
* If function returns NULL, it means the table doesn't exist
* hence we should skip
*/
Relation relation = try_relation_open(relationId, AccessShareLock);
if (relation != NULL)
{
List *shardIntervalsOnNode = ShardIntervalsOnWorkerGroup(workerNode,
relationId);
char *shardStatisticsQuery =
GenerateShardStatisticsQueryForShardList(shardIntervalsOnNode,
useShardMinMaxQuery);
appendStringInfoString(allShardStatisticsQuery, shardStatisticsQuery);
relation_close(relation, AccessShareLock);
}
}
/* Add a dummy entry so that UNION ALL doesn't complain */

27
src/backend/distributed/operations/stage_protocol.c
View File

@ -380,7 +380,32 @@ citus_update_table_statistics(PG_FUNCTION_ARGS)
Oid distributedTableId = PG_GETARG_OID(0);
UpdateTableStatistics(distributedTableId);
/*
* Ensure the table still exists by trying to acquire a lock on it
* If function returns NULL, it means the table doesn't exist
* hence we should skip
*/
Relation relation = try_relation_open(distributedTableId, AccessShareLock);
if (relation != NULL)
{
UpdateTableStatistics(distributedTableId);
/*
* We release the lock here since citus_update_table_statistics
* is usually used in the following command:
* SELECT citus_update_table_statistics(logicalrelid) FROM pg_dist_partition;
* In this way we avoid holding the locks on distributed tables for a long time:
* If we close the relation with NoLock, the locks on the distributed tables will
* be held until the above command is finished (all distributed tables are updated).
*/
relation_close(relation, AccessShareLock);
}
else
{
ereport(NOTICE, (errmsg("relation with OID %u does not exist, skipping",
distributedTableId)));
}
PG_RETURN_VOID();
}

90
src/test/regress/expected/isolation_citus_update_table_statistics.out Normal file
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@ -0,0 +1,90 @@
Parsed test spec with 2 sessions
starting permutation: s1-begin s1-drop-table s2-citus-update-table-statistics s1-commit
create_distributed_table
step s1-begin:
BEGIN;
step s1-drop-table:
DROP TABLE dist_table;
step s2-citus-update-table-statistics:
SET client_min_messages TO NOTICE;
SELECT citus_update_table_statistics(logicalrelid) FROM pg_dist_partition;
<waiting ...>
step s1-commit:
COMMIT;
step s2-citus-update-table-statistics: <... completed>
s2: NOTICE: relation with OID XXXX does not exist, skipping
citus_update_table_statistics
starting permutation: s1-begin s1-drop-table s2-citus-shards s1-commit
create_distributed_table
step s1-begin:
BEGIN;
step s1-drop-table:
DROP TABLE dist_table;
step s2-citus-shards:
SELECT 1 AS result FROM citus_shards GROUP BY result;
<waiting ...>
step s1-commit:
COMMIT;
step s2-citus-shards: <... completed>
result
1
starting permutation: s2-begin s2-citus-shards s1-drop-table s2-commit
create_distributed_table
step s2-begin:
BEGIN;
step s2-citus-shards:
SELECT 1 AS result FROM citus_shards GROUP BY result;
result
1
step s1-drop-table:
DROP TABLE dist_table;
step s2-commit:
COMMIT;
starting permutation: s2-begin s2-citus-update-table-statistics s1-drop-table s2-commit
create_distributed_table
step s2-begin:
BEGIN;
step s2-citus-update-table-statistics:
SET client_min_messages TO NOTICE;
SELECT citus_update_table_statistics(logicalrelid) FROM pg_dist_partition;
citus_update_table_statistics
step s1-drop-table:
DROP TABLE dist_table;
<waiting ...>
step s2-commit:
COMMIT;
step s1-drop-table: <... completed>
error in steps s2-commit s1-drop-table: ERROR: tuple concurrently deleted

1
src/test/regress/isolation_schedule
View File

@ -65,6 +65,7 @@ test: isolation_multiuser_locking
test: shared_connection_waits
test: isolation_cancellation
test: isolation_undistribute_table
test: isolation_citus_update_table_statistics
# Rebalancer
test: isolation_blocking_move_single_shard_commands

59
src/test/regress/spec/isolation_citus_update_table_statistics.spec Normal file
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@ -0,0 +1,59 @@
setup
{
CREATE TABLE dist_table(a INT, b INT);
SELECT create_distributed_table('dist_table', 'a');
}
teardown
{
DROP TABLE IF EXISTS dist_table;
}
session "s1"
step "s1-begin"
{
BEGIN;
}
step "s1-drop-table"
{
DROP TABLE dist_table;
}
step "s1-commit"
{
COMMIT;
}
session "s2"
step "s2-begin"
{
BEGIN;
}
step "s2-citus-update-table-statistics"
{
SET client_min_messages TO NOTICE;
SELECT citus_update_table_statistics(logicalrelid) FROM pg_dist_partition;
}
step "s2-citus-shards"
{
SELECT 1 AS result FROM citus_shards GROUP BY result;
}
step "s2-commit"
{
COMMIT;
}
permutation "s1-begin" "s1-drop-table" "s2-citus-update-table-statistics" "s1-commit"
permutation "s1-begin" "s1-drop-table" "s2-citus-shards" "s1-commit"
permutation "s2-begin" "s2-citus-shards" "s1-drop-table" "s2-commit"
// ERROR: tuple concurrently deleted -- is expected in the following permutation
// Check the explanation at PR #5155 in the following comment
// https://github.com/citusdata/citus/pull/5155#issuecomment-897028194
permutation "s2-begin" "s2-citus-update-table-statistics" "s1-drop-table" "s2-commit"