Hi Chao,
Thanks for the thorough review.
On 25/03/2026 02:55, Chao Li wrote:
> It uses isTempOrTempToastNamespace(relation->rd_rel->relnamespace) to decide
> relation->rd_islocaltemp.
>
> So, I think this patch should also use
> "!isTempOrTempToastNamespace(classForm->relnamespace)" instead of
> isOtherTempNamespace(class->relnamespace). I tried that locally, and it works
> for me.
I agree. In get_all_vacuum_rels() and the pg_class scan branch of
get_tables_to_repack(), relpersistence == RELPERSISTENCE_TEMP already
establishes the relation is a temp table, so
!isTempOrTempToastNamespace() alone is sufficient to identify
other-session temp tables.
In the usingindex path of get_tables_to_repack(), Form_pg_class is not
available, so there is no relpersistence to use as a pre-filter. The
explicit isAnyTempNamespace() check is required to avoid incorrectly
skipping permanent tables. This is pretty much what
isOtherTempNamespace() does internally -- the only change is inlining it
to avoid the obsolete wrapper.
* Skip temp relations belonging to other sessions */
{
Oid nsp = get_rel_namespace(index->indrelid);
if (!isTempOrTempToastNamespace(nsp) && isAnyTempNamespace(nsp))
{
UnlockRelationOid(index->indrelid, AccessShareLock);
continue;
}
}
v2 attached.
Thanks!
Best, JimFrom 5f8528db5d457ddc3158b00b7768c8e088e1e577 Mon Sep 17 00:00:00 2001
From: Jim Jones <[email protected]>
Date: Wed, 25 Mar 2026 09:34:06 +0100
Subject: [PATCH v2] Skip other sessions' temp tables in REPACK, CLUSTER, and
VACUUM FULL
get_tables_to_repack() was including other sessions' temporary tables
in the work list, causing REPACK and CLUSTER (without arguments) to
attempt to acquire AccessExclusiveLock on them, potentially blocking
for an extended time. Fix by skipping other-session temp tables early
in get_tables_to_repack(), before they are added to the list. Because
an AccessShareLock has already been acquired per relation at that
point, release it before continuing.
Similarly, get_all_vacuum_rels() suffered from the same problem for
VACUUM FULL. Since no per-relation lock is held during list-building
there, a plain skip suffices.
Author: Jim Jones <[email protected]>
Reviewed-by: Chao Li <[email protected]>
---
src/backend/commands/cluster.c | 19 +++++++++++++++++++
src/backend/commands/vacuum.c | 5 +++++
2 files changed, 24 insertions(+)
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 09066db0956..386bd34c16b 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1699,6 +1699,17 @@ get_tables_to_repack(RepackCommand cmd, bool usingindex, MemoryContext permcxt)
continue;
}
+ /* Skip temp relations belonging to other sessions */
+ {
+ Oid nsp = get_rel_namespace(index->indrelid);
+
+ if (!isTempOrTempToastNamespace(nsp) && isAnyTempNamespace(nsp))
+ {
+ UnlockRelationOid(index->indrelid, AccessShareLock);
+ continue;
+ }
+ }
+
/* noisily skip rels which the user can't process */
if (!repack_is_permitted_for_relation(cmd, index->indrelid,
GetUserId()))
@@ -1753,6 +1764,14 @@ get_tables_to_repack(RepackCommand cmd, bool usingindex, MemoryContext permcxt)
continue;
}
+ /* Skip temp relations belonging to other sessions */
+ if (class->relpersistence == RELPERSISTENCE_TEMP &&
+ !isTempOrTempToastNamespace(class->relnamespace))
+ {
+ UnlockRelationOid(class->oid, AccessShareLock);
+ continue;
+ }
+
/* noisily skip rels which the user can't process */
if (!repack_is_permitted_for_relation(cmd, class->oid,
GetUserId()))
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index bce3a2daa24..9b0a5a38a8a 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -1062,6 +1062,11 @@ get_all_vacuum_rels(MemoryContext vac_context, int options)
classForm->relkind != RELKIND_PARTITIONED_TABLE)
continue;
+ /* Skip temp relations belonging to other sessions */
+ if (classForm->relpersistence == RELPERSISTENCE_TEMP &&
+ !isTempOrTempToastNamespace(classForm->relnamespace))
+ continue;
+
/* check permissions of relation */
if (!vacuum_is_permitted_for_relation(relid, classForm, options))
continue;
--
2.43.0
