Only allow heap in a number of contrib modules.

Contrib modules pgrowlocks, pgstattuple and some functionality in
pageinspect currently only supports the heap table AM. As they are all
concerned with low-level details that aren't reasonably exposed via
tableam, error out if invoked on a non heap relation.

Author: Andres Freund
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de

contrib/pageinspect/heapfuncs.c

@@ -30,6 +30,7 @@
 #include "access/htup_details.h"
 #include "access/relation.h"
 #include "funcapi.h"
+#include "catalog/pg_am_d.h"
 #include "catalog/pg_type.h"
 #include "miscadmin.h"
 #include "utils/array.h"
@@ -318,6 +319,10 @@ tuple_data_split_internal(Oid relid, char *tupdata,
 	raw_attrs = initArrayResult(BYTEAOID, CurrentMemoryContext, false);
 	nattrs = tupdesc->natts;
 
+	if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
+		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("only heap AM is supported")));
+
 	if (nattrs < (t_infomask2 & HEAP_NATTS_MASK))
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),

contrib/pgrowlocks/pgrowlocks.c

@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/xact.h"
 #include "catalog/namespace.h"
+#include "catalog/pg_am_d.h"
 #include "catalog/pg_authid.h"
 #include "funcapi.h"
 #include "miscadmin.h"
@@ -101,6 +102,10 @@ pgrowlocks(PG_FUNCTION_ARGS)
 		relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
 		rel = relation_openrv(relrv, AccessShareLock);
 
+		if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
+			ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							errmsg("only heap AM is supported")));
+
 		if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),

contrib/pgstattuple/pgstatapprox.c

@@ -20,6 +20,8 @@
 #include "access/multixact.h"
 #include "access/htup_details.h"
 #include "catalog/namespace.h"
+#include "catalog/pg_am_d.h"
+#include "commands/vacuum.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "storage/bufmgr.h"
@@ -27,7 +29,6 @@
 #include "storage/procarray.h"
 #include "storage/lmgr.h"
 #include "utils/builtins.h"
-#include "commands/vacuum.h"
 
 PG_FUNCTION_INFO_V1(pgstattuple_approx);
 PG_FUNCTION_INFO_V1(pgstattuple_approx_v1_5);
@@ -291,6 +292,10 @@ pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo)
 				 errmsg("\"%s\" is not a table or materialized view",
 						RelationGetRelationName(rel))));
 
+	if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
+		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("only heap AM is supported")));
+
 	statapprox_heap(rel, &stat);
 
 	relation_close(rel, AccessShareLock);

contrib/pgstattuple/pgstattuple.c

@@ -31,7 +31,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "catalog/namespace.h"
-#include "catalog/pg_am.h"
+#include "catalog/pg_am_d.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "storage/bufmgr.h"
@@ -328,6 +328,11 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
 	pgstattuple_type stat = {0};
 	SnapshotData SnapshotDirty;
 
+	if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only heap AM is supported")));
+
 	/* Disable syncscan because we assume we scan from block zero upwards */
 	scan = table_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);
 	hscan = (HeapScanDesc) scan;