Subject: [PATCH] Fix misuses of RelationNeedsWAL

From: Kyotaro Horiguchi <[email-masked]>
Date: Wed, 13 Jan 2021 15:52:03 +0900

The definition of the macro RelationNeedsWAL has been changed by
c6b92041d3 to include conditions related to the WAL-skip optimization
but some uses of the macro are not relevant to the optimization. That
misuses are harmless for now as they are only executed while wal_level
>= replica or WAL-skipping is inactive. However, this should be
corrected to prevent future hazard.
---
 src/backend/catalog/pg_publication.c |  2 +-
 src/backend/optimizer/util/plancat.c |  2 +-
 src/include/utils/rel.h              | 15 +++++++++++----
 src/include/utils/snapmgr.h          |  2 +-
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/backend/catalog/pg_publication.c b/src/backend/catalog/pg_publication.c
index 5f8e1c64e1..f3060a4cf1 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 (!RelationIsWalLogged(targetrel))
 		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..0500efcdb9 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -126,7 +126,7 @@ 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 (!RelationIsWalLogged(relation) && RecoveryInProgress())
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot access temporary or unlogged relations during recovery")));
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 10b63982c0..810806a542 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -552,16 +552,23 @@ typedef struct ViewOptions
 		(relation)->rd_smgr->smgr_targblock = (targblock); \
 	} while (0)
 
+/*
+ * RelationIsPermanent
+ *		True if relation is WAL-logged.
+ */
+#define RelationIsWalLogged(relation)									\
+	((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
+
 /*
  * 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
  * RelFileNode" in src/backend/access/transam/README.
  */
 #define RelationNeedsWAL(relation)										\
-	((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT &&	\
+	(RelationIsWalLogged(relation) &&									\
 	 (XLogIsNeeded() ||													\
 	  (relation->rd_createSubid == InvalidSubTransactionId &&			\
 	   relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)))
@@ -619,7 +626,7 @@ typedef struct ViewOptions
  */
 #define RelationIsAccessibleInLogicalDecoding(relation) \
 	(XLogLogicalInfoActive() && \
-	 RelationNeedsWAL(relation) && \
+	 RelationIsWalLogged(relation) && \
 	 (IsCatalogRelation(relation) || RelationIsUsedAsCatalogTable(relation)))
 
 /*
@@ -635,7 +642,7 @@ typedef struct ViewOptions
  */
 #define RelationIsLogicallyLogged(relation) \
 	(XLogLogicalInfoActive() && \
-	 RelationNeedsWAL(relation) && \
+	 RelationIsWalLogged(relation) && \
 	 !IsCatalogRelation(relation))
 
 /* routines in utils/cache/relcache.c */
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h
index 579be352c5..7be922a9f1 100644
--- a/src/include/utils/snapmgr.h
+++ b/src/include/utils/snapmgr.h
@@ -37,7 +37,7 @@
  */
 #define RelationAllowsEarlyPruning(rel) \
 ( \
-	 RelationNeedsWAL(rel) \
+	 RelationIsWalLogged(rel) \
   && !IsCatalogRelation(rel) \
   && !RelationIsAccessibleInLogicalDecoding(rel) \
 )
-- 
2.27.0

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