diff options
| -rw-r--r-- | src/backend/commands/tablecmds.c | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 562c815c63f..f27684f96e4 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -13997,10 +13997,9 @@ QueuePartitionConstraintValidation(List **wqueue, Relation scanrel, List *thisPartConstraint; /* - * This is the minimum lock we need to prevent concurrent data - * additions. + * This is the minimum lock we need to prevent deadlocks. */ - part_rel = heap_open(partdesc->oids[i], ShareLock); + part_rel = heap_open(partdesc->oids[i], AccessExclusiveLock); /* * Adjust the constraint for scanrel so that it matches this @@ -14113,17 +14112,17 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd) * * We do that by checking if rel is a member of the list of attachrel's * partitions provided the latter is partitioned at all. We want to avoid - * having to construct this list again, so we request a lock on all - * partitions. We need ShareLock, preventing data changes, because we - * may decide to scan them if we find out that the table being attached (or - * its leaf partitions) may contain rows that violate the partition - * constraint. If the table has a constraint that would prevent such rows, - * which by definition is present in all the partitions, we need not scan - * the table, nor its partitions. But we cannot risk a deadlock by taking - * a weaker lock now and the stronger one only when needed. + * having to construct this list again, so we request the strongest lock + * on all partitions. We need the strongest lock, because we may decide + * to scan them if we find out that the table being attached (or its leaf + * partitions) may contain rows that violate the partition constraint. If + * the table has a constraint that would prevent such rows, which by + * definition is present in all the partitions, we need not scan the + * table, nor its partitions. But we cannot risk a deadlock by taking a + * weaker lock now and the stronger one only when needed. */ attachrel_children = find_all_inheritors(RelationGetRelid(attachrel), - ShareLock, NULL); + AccessExclusiveLock, NULL); if (list_member_oid(attachrel_children, RelationGetRelid(rel))) ereport(ERROR, (errcode(ERRCODE_DUPLICATE_TABLE), |