From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Thu, 20 Dec 2018 19:42:13 +0000 (-0300)
Subject: Fix lock level used for partition when detaching it
X-Git-Tag: REL_11_2~108
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=053ad56d275d343b407bc5fd389bad6f3e340562;p=postgresql

Fix lock level used for partition when detaching it

For probably bogus reasons, we acquire only AccessShareLock on the
partition when we try to detach it from its parent partitioned table.
This can cause ugly things to happen if another transaction is doing
any sort of DDL to the partition concurrently.

Upgrade that lock to ShareUpdateExclusiveLock, which per discussion
seems to be the minimum needed.

Reported 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
index 6543eedc3a..1dae356360 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -14726,7 +14726,7 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 	if (OidIsValid(defaultPartOid))
 		LockRelationOid(defaultPartOid, AccessExclusiveLock);
 
-	partRel = heap_openrv(name, AccessShareLock);
+	partRel = heap_openrv(name, ShareUpdateExclusiveLock);
 
 	/* All inheritance related checks are performed within the function */
 	RemoveInheritance(partRel, rel);