Revisit pathman readiness again.

arssher · arssher · commit 16810d9211e8 · 2019-02-01T16:06:23.000+03:00
Most pathman functions break if pathman is disabled: earlier I put defense
checks in split and merge range partitions, now it is
drop_range_partition_expand_next. Looks like the reason is that pathman caches
are not being invalidated if it is disabled: pathman_relcache_hook exits right
away then. This is kinda reasonable: if we want to disable pathman completely,
why maintain the caches? So this time try to bury the readiness check deeper,
in get_pathman_relation_info itself.

BTW, pathman caches are not dropped when it is disabled, which looks suspicious
on its own -- probably if we re-enable it later, caches might be inconsistent.
diff --git a/expected/pathman_calamity.out b/expected/pathman_calamity.out
@@ -1009,7 +1009,7 @@ ERROR:  pg_pathman is disabled
 SELECT * FROM pathman_partition_list;							/* not ok */
 ERROR:  pg_pathman is not initialized yet
 SELECT get_part_range('calamity.survivor', 0, NULL::INT);		/* not ok */
-ERROR:  pg_pathman is not initialized yet
+ERROR:  pg_pathman is disabled
 EXPLAIN (COSTS OFF) SELECT * FROM calamity.survivor;			/* OK */
           QUERY PLAN          
 ------------------------------
diff --git a/src/pl_range_funcs.c b/src/pl_range_funcs.c
@@ -489,9 +489,6 @@ split_range_partition(PG_FUNCTION_ARGS)
 	char			   *query;
 	int					i;
 
-	if (!IsPathmanReady())
-		elog(ERROR, "pg_pathman is disabled");
-
 	if (!PG_ARGISNULL(0))
 	{
 		partition1 = PG_GETARG_OID(0);
@@ -655,9 +652,6 @@ merge_range_partitions(PG_FUNCTION_ARGS)
 	FmgrInfo			finfo;
 	int					i;
 
-	if (!IsPathmanReady())
-		elog(ERROR, "pg_pathman is disabled");
-
 	/* Validate array type */
 	Assert(ARR_ELEMTYPE(arr) == REGCLASSOID);
 
diff --git a/src/relation_info.c b/src/relation_info.c
@@ -320,6 +320,9 @@ get_pathman_relation_info(Oid relid)
 {
 	PartStatusInfo *psin;
 
+	if (!IsPathmanReady())
+		elog(ERROR, "pg_pathman is disabled");
+
 	/* Should always be called in transaction */
 	Assert(IsTransactionState());
 

Original file line number	Diff line number	Diff line change
`@@ -320,6 +320,9 @@ get_pathman_relation_info(Oid relid)`
`320`	`320`	`{`
`321`	`321`	`PartStatusInfo *psin;`
`322`	`322`
	`323`	`+ if (!IsPathmanReady())`
	`324`	`+ elog(ERROR, "pg_pathman is disabled");`
	`325`	`+`
`323`	`326`	`/* Should always be called in transaction */`
`324`	`327`	`Assert(IsTransactionState());`
`325`	`328`