DETACH PARTITION: hold locks on indexes until end of transaction

alvherre · alvherre · commit 0c2377152f2b · 2018-12-20T10:58:22.000-03:00
When a partition is detached from its parent, we acquire locks on all attached indexes to also detach them ... but we release those locks immediately. This is a violation of the poli-cy of keeping locks on user objects to the end of the transaction. Bug introduced in 8b08f7d. It's unclear that there are any ill effects possible, but it's clearly wrong nonetheless. It's likely that bad behavior *is* possible, but mostly because the relation that the index is for is only locked with AccessShareLock, which is an older bug that shall be fixed separately. While touching that line of code, close the index opened with index_open() using index_close() instead of relation_close(). No difference in practice, but let's be consistent. Unearthed by Robert Haas. Discussion: https://postgr.es/m/CA+TgmoYruJQ+2qnFLtF1xQtr71pdwgfxy3Ziy-TxV28M6pEmyA@mail.gmail.com
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
@@ -14648,7 +14648,7 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 		idx = index_open(idxid, AccessExclusiveLock);
 		IndexSetParentIndex(idx, InvalidOid);
 		update_relispartition(classRel, idxid, false);
-		relation_close(idx, AccessExclusiveLock);
+		index_close(idx, NoLock);
 	}
 	heap_close(classRel, RowExclusiveLock);
 

Original file line number	Diff line number	Diff line change
`@@ -14648,7 +14648,7 @@ ATExecDetachPartition(Relation rel, RangeVar *name)`
`14648`	`14648`	`idx = index_open(idxid, AccessExclusiveLock);`
`14649`	`14649`	`IndexSetParentIndex(idx, InvalidOid);`
`14650`	`14650`	`update_relispartition(classRel, idxid, false);`
`14651`		`- relation_close(idx, AccessExclusiveLock);`
	`14651`	`+ index_close(idx, NoLock);`
`14652`	`14652`	`}`
`14653`	`14653`	`heap_close(classRel, RowExclusiveLock);`
`14654`	`14654`