Retain relkind too in RTE_SUBQUERY entries for views.

47bb9db modified the ApplyRetrieveRule()'s conversion of a view's
original RTE_RELATION entry into an RTE_SUBQUERY one to retain relid,
rellockmode, and perminfoindex so that the executor can lock the view
and check its permissions.  It seems better to also retain
relkind for cross-checking that the exception of an
RTE_SUBQUERY entry being allowed to carry relation details only
applies to views, so do so.

Bump catversion because this changes the output format of
RTE_SUBQUERY RTEs.

Suggested-by: David Steele <david@pgmasters.net>
Reviewed-by: David Steele <david@pgmasters.net>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/3953179e-9540-e5d1-a743-4bef368785b0%40pgmasters.net

Author: amitlan

src/backend/executor/execMain.c

@@ -595,6 +595,15 @@ ExecCheckPermissions(List *rangeTable, List *rteperminfos,
 		if (rte->perminfoindex != 0)
 		{
 			/* Sanity checks */
+
+			/*
+			 * Only relation RTEs and subquery RTEs that were once relation
+			 * RTEs (views) have their perminfoindex set.
+			 */
+			Assert(rte->rtekind == RTE_RELATION ||
+				   (rte->rtekind == RTE_SUBQUERY &&
+					rte->relkind == RELKIND_VIEW));
+
 			(void) getRTEPermissionInfo(rteperminfos, rte);
 			/* Many-to-one mapping not allowed */
 			Assert(!bms_is_member(rte->perminfoindex, indexset));

src/backend/nodes/outfuncs.c

@@ -513,6 +513,7 @@ _outRangeTblEntry(StringInfo str, const RangeTblEntry *node)
 			WRITE_BOOL_FIELD(security_barrier);
 			/* we re-use these RELATION fields, too: */
 			WRITE_OID_FIELD(relid);
+			WRITE_CHAR_FIELD(relkind);
 			WRITE_INT_FIELD(rellockmode);
 			WRITE_UINT_FIELD(perminfoindex);
 			break;

src/backend/nodes/readfuncs.c

@@ -503,6 +503,7 @@ _readRangeTblEntry(void)
 			READ_BOOL_FIELD(security_barrier);
 			/* we re-use these RELATION fields, too: */
 			READ_OID_FIELD(relid);
+			READ_CHAR_FIELD(relkind);
 			READ_INT_FIELD(rellockmode);
 			READ_UINT_FIELD(perminfoindex);
 			break;

src/backend/rewrite/rewriteHandler.c

@@ -1851,11 +1851,10 @@ ApplyRetrieveRule(Query *parsetree,
 
 	/*
 	 * Clear fields that should not be set in a subquery RTE.  Note that we
-	 * leave the relid, rellockmode, and perminfoindex fields set, so that the
-	 * view relation can be appropriately locked before execution and its
-	 * permissions checked.
+	 * leave the relid, relkind, rellockmode, and perminfoindex fields set, so
+	 * that the view relation can be appropriately locked before execution and
+	 * its permissions checked.
 	 */
-	rte->relkind = 0;
 	rte->tablesample = NULL;
 	rte->inh = false;			/* must not be set for a subquery */
 

src/include/catalog/catversion.h

@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202305211
+#define CATALOG_VERSION_NO	202306141
 
 #endif

src/include/nodes/parsenodes.h

@@ -1056,13 +1056,13 @@ typedef struct RangeTblEntry
 	 * this RTE in the containing struct's list of same; 0 if permissions need
 	 * not be checked for this RTE.
 	 *
-	 * As a special case, relid, rellockmode, and perminfoindex can also be
-	 * set (nonzero) in an RTE_SUBQUERY RTE.  This occurs when we convert an
-	 * RTE_RELATION RTE naming a view into an RTE_SUBQUERY containing the
-	 * view's query.  We still need to perform run-time locking and permission
-	 * checks on the view, even though it's not directly used in the query
-	 * anymore, and the most expedient way to do that is to retain these
-	 * fields from the old state of the RTE.
+	 * As a special case, relid, relkind, rellockmode, and perminfoindex can
+	 * also be set (nonzero) in an RTE_SUBQUERY RTE.  This occurs when we
+	 * convert an RTE_RELATION RTE naming a view into an RTE_SUBQUERY
+	 * containing the view's query.  We still need to perform run-time locking
+	 * and permission checks on the view, even though it's not directly used
+	 * in the query anymore, and the most expedient way to do that is to
+	 * retain these fields from the old state of the RTE.
 	 *
 	 * As a special case, RTE_NAMEDTUPLESTORE can also set relid to indicate
 	 * that the tuple format of the tuplestore is the same as the referenced