database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-05-12 16:21:30 +03:00
Code

Have DISCARD ALL/TEMP remove leftover temp tables

Browse Source 
Previously, it would only remove temp tables created in the same
session; but if the session uses the BackendId of a previously crashed
backend that left temp tables around, those would not get removed.
Since autovacuum would not drop them either (because it sees that the
BackendId is in use by the current session) these can cause annoying
xid-wraparound warnings.

Apply to branches 9.4 to 10.  This is not a problem since version 11,
because commit 943576bddcb5 added state tracking that makes autovacuum
realize that those temp tables are not ours, so it removes them.

This is useful to handle in DISCARD, because even though it does not
handle all situations, it does handle the common one where a connection
pooler keeps the same session open for an indefinitely long time.

Discussion: https://postgr.es/m/20181226190834.wsk2wzott5yzrjiq@alvherre.pgsql
Reviewed-by: Takayuki Tsunakawa, Michaël Paquier
This commit is contained in:
Alvaro Herrera 2018-12-27 16:17:40 -03:00
parent 7fc2363a61
commit aa2e84d2cc
1 changed files with 19 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/backend/catalog/namespace.c
View File

@ -3902,12 +3902,31 @@ RemoveTempRelationsCallback(int code, Datum arg)
/* /*
* Remove all temp tables from the temporary namespace. * Remove all temp tables from the temporary namespace.
*
* If we haven't set up one yet, but one exists from a previous crashed
* backend, clean that one; but only do this once in a session's life.
*/ */
void void
ResetTempTableNamespace(void) ResetTempTableNamespace(void)
{ {
static bool TempNamespaceCleaned = false;
if (OidIsValid(myTempNamespace)) if (OidIsValid(myTempNamespace))
RemoveTempRelations(myTempNamespace); RemoveTempRelations(myTempNamespace);
else if (MyBackendId != InvalidBackendId && !RecoveryInProgress() &&
!TempNamespaceCleaned)
{
char namespaceName[NAMEDATALEN];
Oid namespaceId;
snprintf(namespaceName, sizeof(namespaceName), "pg_temp_%d",
MyBackendId);
namespaceId = get_namespace_oid(namespaceName, true);
if (OidIsValid(namespaceId))
RemoveTempRelations(namespaceId);
}
TempNamespaceCleaned = true;
} }