Update AO visimap char from 'm' to 'M' in pg_upgrade

Relkind 'm' stands for materialized view now. This addressed a
GPDB_93_MERGE_FIXME.
Co-authored-by: NAlexandra Wang <lewang@pivotal.io>
Co-authored-by: NJimmy Yih <jyih@pivotal.io>

contrib/pg_upgrade/info.c

@@ -532,7 +532,7 @@ get_rel_infos(ClusterInfo *cluster, DbInfo *dbinfo)
 			 "	   ON c.relnamespace = n.oid "
 			 "LEFT OUTER JOIN pg_catalog.pg_index i "
 			 "	   ON c.oid = i.indexrelid "
-			 "WHERE relkind IN ('r', 'o', 'm', 'b', 'i'%s) AND "
+			 "WHERE relkind IN ('r', 'o', 'b', 'i'%s%s) AND "
 
 	/*
 	 * pg_dump only dumps valid indexes;  testing indisready is necessary in
@@ -551,6 +551,9 @@ get_rel_infos(ClusterInfo *cluster, DbInfo *dbinfo)
 			 "	  c.oid >= %u) "
 			 "  OR (n.nspname = 'pg_catalog' AND "
 	"    relname IN ('pg_largeobject', 'pg_largeobject_loid_pn_index'%s) ));",
+	/* Greenplum 4.3/5X use 'm' as aovisimap which is now matview in 6X and above. */
+			 (GET_MAJOR_VERSION(old_cluster.major_version) <= 803) ?
+			 ", 'm'" : ", 'M'",
 	/* see the comment at the top of old_8_3_create_sequence_script() */
 			 (GET_MAJOR_VERSION(old_cluster.major_version) <= 803) ?
 			 "" : ", 'S'",

contrib/pg_upgrade/pg_upgrade.c

@@ -995,10 +995,14 @@ set_frozenxids(bool minmxid_only)
 			 *
 			 * The logic here should keep consistent with function
 			 * should_have_valid_relfrozenxid().
+			 *
+			 * Notes: if we ever backport this to Greenplum 5X, remove 'm' first
+			 * and then replace 'M' with 'm', because 'm' used to be RELKIND
+			 * visimap in 4.3/5X, not matview
 			 */
 									  "WHERE	(relkind IN ('r', 'm', 't') "
 									  "AND NOT relfrozenxid = 0) "
-									  "OR (relkind IN ('t', 'o', 'b', 'm'))",
+									  "OR (relkind IN ('t', 'o', 'b', 'M'))",
 									  old_cluster.controldata.chkpnt_nxtxid));
 
 		/* set pg_class.relminmxid */

src/include/catalog/pg_class.h

@@ -172,10 +172,6 @@ DESCR("");
 #define		  RELKIND_AOSEGMENTS	  'o'		/* AO segment files and eof's */
 #define		  RELKIND_AOBLOCKDIR	  'b'		/* AO block directory */
 #define		  RELKIND_AOVISIMAP		  'M'		/* AO visibility map */
-// GPDB_93_MERGE_FIXME: RELKIND_AOVISIMAP used to be 'm', but that means MATVIEW now.
-// Find all the places where it might be referred to using just 'm', without using this
-// macro. E.g. pg_dump and psql. They might need to also work differently depending
-// on version.
 
 #define		  RELPERSISTENCE_PERMANENT	'p'		/* regular table */
 #define		  RELPERSISTENCE_UNLOGGED	'u'		/* unlogged permanent table */