Add macro RelationIsPermanent() to report relation permanence

Previously, to check relation permanence, the Relation's Form_pg_class
structure member relpersistence was compared to the value
RELPERSISTENCE_PERMANENT ("p"). This commit adds the macro
RelationIsPermanent() and is used in appropirate places to simplify the
code.  This matches other RelationIs* macros.

This macro will be used in more places in future cluster file encryption
patches.

Discussion: https://postgr.es/m/20210318153134.GH20766@tamriel.snowman.net

src/backend/access/gist/gistutil.c

@@ -1036,7 +1036,7 @@ gistGetFakeLSN(Relation rel)
 
 		return counter++;
 	}
-	else if (rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
+	else if (RelationIsPermanent(rel))
 	{
 		/*
 		 * WAL-logging on this relation will start after commit, so its LSNs

src/backend/access/heap/heapam_handler.c

@@ -662,7 +662,7 @@ heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode)
 			 * WAL log creation if the relation is persistent, or this is the
 			 * init fork of an unlogged relation.
 			 */
-			if (rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT ||
+			if (RelationIsPermanent(rel) ||
 				(rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
 				 forkNum == INIT_FORKNUM))
 				log_smgrcreate(newrnode, forkNum);

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 (targetrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT)
+	if (!RelationIsPermanent(targetrel))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("table \"%s\" cannot be replicated",

src/backend/commands/tablecmds.c

@@ -8650,13 +8650,13 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	switch (rel->rd_rel->relpersistence)
 	{
 		case RELPERSISTENCE_PERMANENT:
-			if (pkrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT)
+			if (!RelationIsPermanent(pkrel))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 						 errmsg("constraints on permanent tables may reference only permanent tables")));
 			break;
 		case RELPERSISTENCE_UNLOGGED:
-			if (pkrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT
+			if (!RelationIsPermanent(pkrel)
 				&& pkrel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
@@ -13712,7 +13712,7 @@ index_copy_data(Relation rel, RelFileNode newrnode)
 			 * WAL log creation if the relation is persistent, or this is the
 			 * init fork of an unlogged relation.
 			 */
-			if (rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT ||
+			if (RelationIsPermanent(rel) ||
 				(rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
 				 forkNum == INIT_FORKNUM))
 				log_smgrcreate(&newrnode, forkNum);
@@ -15230,7 +15230,7 @@ ATPrepChangePersistence(Relation rel, bool toLogged)
 
 			if (toLogged)
 			{
-				if (foreignrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT)
+				if (!RelationIsPermanent(foreignrel))
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 							 errmsg("could not change table \"%s\" to logged because it references unlogged table \"%s\"",
@@ -15240,7 +15240,7 @@ ATPrepChangePersistence(Relation rel, bool toLogged)
 			}
 			else
 			{
-				if (foreignrel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
+				if (RelationIsPermanent(foreignrel))
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 							 errmsg("could not change table \"%s\" to unlogged because it references logged table \"%s\"",

src/backend/optimizer/util/plancat.c

@@ -126,8 +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 (relation->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT &&
-		RecoveryInProgress())
+	if (!RelationIsPermanent(relation) && RecoveryInProgress())
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot access temporary or unlogged relations during recovery")));

src/backend/utils/cache/relcache.c

@@ -2990,7 +2990,7 @@ static void
 AssertPendingSyncConsistency(Relation relation)
 {
 	bool		relcache_verdict =
-	relation->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT &&
+	RelationIsPermanent(relation) &&
 	((relation->rd_createSubid != InvalidSubTransactionId &&
 	  RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) ||
 	 relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId);

src/include/utils/rel.h

@@ -577,6 +577,13 @@ typedef struct PartitionedTableRdOptions
 		(relation)->rd_smgr->smgr_targblock = (targblock); \
 	} while (0)
 
+/*
+ * RelationIsPermanent
+ *		True if relation is permanent.
+ */
+#define RelationIsPermanent(relation) \
+	((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
+
 /*
  * RelationNeedsWAL
  *		True if relation needs WAL.
@@ -586,8 +593,7 @@ typedef struct PartitionedTableRdOptions
  * RelFileNode" in src/backend/access/transam/README.
  */
 #define RelationNeedsWAL(relation)										\
-	((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT &&	\
-	 (XLogIsNeeded() ||													\
+	(RelationIsPermanent(relation) && (XLogIsNeeded() ||				\
 	  (relation->rd_createSubid == InvalidSubTransactionId &&			\
 	   relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)))
 

src/include/utils/snapmgr.h

@@ -37,8 +37,7 @@
  */
 #define RelationAllowsEarlyPruning(rel) \
 ( \
-	 (rel)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT	\
-  && !IsCatalogRelation(rel) \
+	 RelationIsPermanent(rel) && !IsCatalogRelation(rel) \
   && !RelationIsAccessibleInLogicalDecoding(rel) \
 )