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help / color / mirror / Atom feedFrom: Kyotaro Horiguchi <[email protected]>
Subject: [PATCH v5 2/3] Do not use RelationNeedsWAL to identify relation persistence
Date: Mon, 18 Jan 2021 14:47:21 +0900
RelationNeedsWAL() may return false for a permanent relation when
wal_level=minimal and the relation is created or truncated in the
current transaction. Directly examine relpersistence instead of using
the function to know relation persistence.
---
src/backend/catalog/pg_publication.c | 2 +-
src/backend/optimizer/util/plancat.c | 3 ++-
src/include/storage/bufmgr.h | 8 +++++++-
src/include/utils/rel.h | 2 +-
src/include/utils/snapmgr.h | 2 +-
5 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/src/backend/catalog/pg_publication.c b/src/backend/catalog/pg_publication.c
index 5f8e1c64e1..84d2efcfd2 100644
--- a/src/backend/catalog/pg_publication.c
+++ b/src/backend/catalog/pg_publication.c
@@ -67,7 +67,7 @@ check_publication_add_relation(Relation targetrel)
errdetail("System tables cannot be added to publications.")));
/* UNLOGGED and TEMP relations cannot be part of publication. */
- if (!RelationNeedsWAL(targetrel))
+ if (targetrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("table \"%s\" cannot be replicated",
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index da322b453e..177e6e336a 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -126,7 +126,8 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
relation = table_open(relationObjectId, NoLock);
/* Temporary and unlogged relations are inaccessible during recovery. */
- if (!RelationNeedsWAL(relation) && RecoveryInProgress())
+ if (relation->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT &&
+ RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot access temporary or unlogged relations during recovery")));
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index fb00fda6a7..e641174798 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -14,6 +14,7 @@
#ifndef BUFMGR_H
#define BUFMGR_H
+#include "access/xlog.h"
#include "storage/block.h"
#include "storage/buf.h"
#include "storage/bufpage.h"
@@ -278,12 +279,17 @@ TestForOldSnapshot(Snapshot snapshot, Relation relation, Page page)
{
Assert(relation != NULL);
+ /*
+ * While wal_level=minimal, early pruning can happen without updating page
+ * LSN. Don't take the fast-return path while wal_level=minimal so that we
+ * don't miss early pruning.
+ */
if (old_snapshot_threshold >= 0
&& (snapshot) != NULL
&& ((snapshot)->snapshot_type == SNAPSHOT_MVCC
|| (snapshot)->snapshot_type == SNAPSHOT_TOAST)
&& !XLogRecPtrIsInvalid((snapshot)->lsn)
- && PageGetLSN(page) > (snapshot)->lsn)
+ && (!XLogIsNeeded() || PageGetLSN(page) > (snapshot)->lsn))
TestForOldSnapshot_impl(snapshot, relation);
}
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 10b63982c0..f58d65cf28 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -554,7 +554,7 @@ typedef struct ViewOptions
/*
* RelationNeedsWAL
- * True if relation needs WAL.
+ * True if relation needs WAL at the time.
*
* Returns false if wal_level = minimal and this relation is created or
* truncated in the current transaction. See "Skipping WAL for New
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h
index 579be352c5..c21ee3c289 100644
--- a/src/include/utils/snapmgr.h
+++ b/src/include/utils/snapmgr.h
@@ -37,7 +37,7 @@
*/
#define RelationAllowsEarlyPruning(rel) \
( \
- RelationNeedsWAL(rel) \
+ (rel)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT \
&& !IsCatalogRelation(rel) \
&& !RelationIsAccessibleInLogicalDecoding(rel) \
)
--
2.27.0
----Next_Part(Thu_Jan_21_00_28_44_2021_003)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
filename="v5-0003-Poc-Keep-page-LSN-updated-while-WAL-skipping.patch"
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