Actually I had a silly bug in the version that attempted to cache a
partdesc that omits detached partitions. This one, while not fully
baked, seems to work correctly (on top of the previous one).
The thing that I don't fully understand is why we have to require to
have built the regular one first.
--
Álvaro Herrera 39°49'30"S 73°17'W
"This is what I like so much about PostgreSQL. Most of the surprises
are of the "oh wow! That's cool" Not the "oh shit!" kind. :)"
Scott Marlowe, http://archives.postgresql.org/pgsql-admin/2008-10/msg00152.php
>From b45e9db9cd08282f7a7fabcef944880cc3a3d415 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Date: Tue, 20 Apr 2021 20:42:30 -0400
Subject: [PATCH] separately cache a partdesc that omits detached partitions,
too
---
src/backend/partitioning/partdesc.c | 21 +++++++++++++++++++--
src/backend/utils/cache/relcache.c | 4 ++++
src/include/utils/rel.h | 1 +
3 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/src/backend/partitioning/partdesc.c b/src/backend/partitioning/partdesc.c
index 7d019a72be..f245cbd664 100644
--- a/src/backend/partitioning/partdesc.c
+++ b/src/backend/partitioning/partdesc.c
@@ -67,10 +67,25 @@ RelationGetPartitionDesc(Relation rel, bool include_detached)
{
Assert(rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
+ /*
+ * The common case is that there are no partitions pending detach and
+ * that the appropriate descriptor has already been built; use that.
+ */
if (likely(rel->rd_partdesc &&
(!rel->rd_partdesc->detached_exist || include_detached)))
return rel->rd_partdesc;
+ /*
+ * If we're asked for a descriptor with detached partitions omitted, and
+ * we have already built it, return that.
+ */
+ if (!include_detached &&
+ rel->rd_partdesc &&
+ rel->rd_partdesc->detached_exist &&
+ rel->rd_partdesc_nodetached)
+ return rel->rd_partdesc_nodetached;
+
+ /* Otherwise build one afresh and store it for next time */
return RelationBuildPartitionDesc(rel, include_detached);
}
@@ -278,9 +293,11 @@ RelationBuildPartitionDesc(Relation rel, bool include_detached)
MemoryContextSetParent(rel->rd_pdcxt, new_pdcxt);
rel->rd_pdcxt = new_pdcxt;
- /* Store it into relcache, but only if no detached partitions exist */
- if (!detached_exist)
+ /* Store it into the appropriate member of the relcache entry */
+ if (!detached_exist || include_detached)
rel->rd_partdesc = partdesc;
+ else
+ rel->rd_partdesc_nodetached = partdesc;
return partdesc;
}
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 29702d6eab..87a7613584 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -1157,6 +1157,7 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
relation->rd_partkey = NULL;
relation->rd_partkeycxt = NULL;
relation->rd_partdesc = NULL;
+ relation->rd_partdesc_nodetached = NULL;
relation->rd_pdcxt = NULL;
relation->rd_partcheck = NIL;
relation->rd_partcheckvalid = false;
@@ -2672,12 +2673,14 @@ RelationClearRelation(Relation relation, bool rebuild)
* newrel.
*/
relation->rd_partdesc = NULL; /* ensure rd_partdesc is invalid */
+ relation->rd_partdesc_nodetached = NULL;
if (relation->rd_pdcxt != NULL) /* probably never happens */
MemoryContextSetParent(newrel->rd_pdcxt, relation->rd_pdcxt);
else
relation->rd_pdcxt = newrel->rd_pdcxt;
/* drop newrel's pointers so we don't destroy it below */
newrel->rd_partdesc = NULL;
+ newrel->rd_partdesc_nodetached = NULL;
newrel->rd_pdcxt = NULL;
}
@@ -5942,6 +5945,7 @@ load_relcache_init_file(bool shared)
rel->rd_partkey = NULL;
rel->rd_partkeycxt = NULL;
rel->rd_partdesc = NULL;
+ rel->rd_partdesc_nodetached = NULL;
rel->rd_pdcxt = NULL;
rel->rd_partcheck = NIL;
rel->rd_partcheckvalid = false;
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 34e25eb597..3d480a3ab2 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -127,6 +127,7 @@ typedef struct RelationData
/* data managed by RelationGetPartitionDesc: */
PartitionDesc rd_partdesc; /* partition descriptor, or NULL */
+ PartitionDesc rd_partdesc_nodetached; /* partition descriptor omitting detached partitions */
MemoryContext rd_pdcxt; /* private context for rd_partdesc, if any */
/* data managed by RelationGetPartitionQual: */
--
2.20.1
