Fix not to create IMMV including other IMMV(#30) (#31)

Previously, IMMV including IMMV in its definition can be created by
create_immv(), but it should not be supported by IMMV because we
cannot maintain it recursively for now. This patch prevents it by raising
an error for such view definition on create_immv().

createas.c

@@ -793,6 +793,11 @@ check_ivm_restriction_walker(Node *node, check_ivm_restriction_context *context)
 						ereport(ERROR,
 								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 								 errmsg("VALUES is not supported on incrementally maintainable materialized view")));
+					if (rte->relkind == RELKIND_RELATION && isImmv(rte->relid))
+						ereport(ERROR,
+								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+								 errmsg("including IMMV in definition is not supported on incrementally maintainable materialized view")));
+
 					if (rte->rtekind == RTE_SUBQUERY)
 					{
 						context->has_subquery = true;

expected/create_immv.out

@@ -26,6 +26,11 @@ SELECT immvrelid, get_immv_def(immvrelid) FROM pg_ivm_immv ORDER BY 1;
            |   WHERE ((i % 2) = 0)
 (2 rows)
 
+-- contain immv
+SELECT create_immv('mv_in_immv01', 'SELECT i FROM mv');
+ERROR:  including IMMV in definition is not supported on incrementally maintainable materialized view
+SELECT create_immv('mv_in_immv02', 'SELECT t.i FROM t INNER JOIN mv2 ON t.i = mv2.x');
+ERROR:  including IMMV in definition is not supported on incrementally maintainable materialized view
 DROP TABLE t;
 ERROR:  cannot drop table t because other objects depend on it
 DETAIL:  table mv depends on table t

pg_ivm.c

@@ -396,3 +396,33 @@ PgIvmObjectAccessHook(ObjectAccessType access, Oid classId,
 		table_close(pgIvmImmv, NoLock);
 	}
 }
+
+/*
+ * isImmv
+ *
+ * Check if this is a IMMV from oid.
+ */
+bool
+isImmv(Oid immv_oid)
+{
+	Relation pgIvmImmv = table_open(PgIvmImmvRelationId(), AccessShareLock);
+	SysScanDesc scan;
+	ScanKeyData key;
+	HeapTuple tup;
+
+	ScanKeyInit(&key,
+			    Anum_pg_ivm_immv_immvrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(immv_oid));
+	scan = systable_beginscan(pgIvmImmv, PgIvmImmvPrimaryKeyIndexId(),
+								  true, NULL, 1, &key);
+	tup = systable_getnext(scan);
+
+	systable_endscan(scan);
+	table_close(pgIvmImmv, NoLock);
+
+	if (!HeapTupleIsValid(tup))
+		return false;
+	else
+		return true;
+}

pg_ivm.h

@@ -30,6 +30,7 @@
 extern void CreateChangePreventTrigger(Oid matviewOid);
 extern Oid PgIvmImmvRelationId(void);
 extern Oid PgIvmImmvPrimaryKeyIndexId(void);
+extern bool isImmv(Oid immv_oid);
 
 /* createas.c */
 

sql/create_immv.sql

@@ -8,6 +8,10 @@ SELECT create_immv('mv3', 'WITH d AS (DELETE FROM t RETURNING NULL) SELECT * FRO
 
 SELECT immvrelid, get_immv_def(immvrelid) FROM pg_ivm_immv ORDER BY 1;
 
+-- contain immv
+SELECT create_immv('mv_in_immv01', 'SELECT i FROM mv');
+SELECT create_immv('mv_in_immv02', 'SELECT t.i FROM t INNER JOIN mv2 ON t.i = mv2.x');
+
 DROP TABLE t;
 
 DROP TABLE mv;