Fix tablespace inheritance for partitioned rels

Commit ca4103025dfe left a few loose ends.  The most important one
(broken pg_dump output) is already fixed by virtue of commit
3b23552ad8bb, but some things remained:

* When ALTER TABLE rewrites tables, the indexes must remain in the
  tablespace they were originally in.  This didn't work because
  index recreation during ALTER TABLE runs manufactured SQL (yuck),
  which runs afoul of default_tablespace in competition with the parent
  relation tablespace.  To fix, reset default_tablespace to the empty
  string temporarily, and add the TABLESPACE clause as appropriate.

* Setting a partitioned rel's tablespace to the database default is
  confusing; if it worked, it would direct the partitions to that
  tablespace regardless of default_tablespace.  But in reality it does
  not work, and making it work is a larger project.  Therefore, throw
  an error when this condition is detected, to alert the unwary.

Add some docs and tests, too.

Author: Álvaro Herrera
Discussion: https://postgr.es/m/CAKJS1f_1c260nOt_vBJ067AZ3JXptXVRohDVMLEBmudX1YEx-A@mail.gmail.com

1 files changed, 26 insertions, 1 deletions

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index a1c91b5fb87..3599c0d8ce0 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -467,8 +467,21 @@ DefineIndex(Oid relationId,
 	LOCKTAG		heaplocktag;
 	LOCKMODE	lockmode;
 	Snapshot	snapshot;
+	int			save_nestlevel = -1;
 	int			i;
 
+	/*
+	 * Some callers need us to run with an empty default_tablespace; this is a
+	 * necessary hack to be able to reproduce catalog state accurately when
+	 * recreating indexes after table-rewriting ALTER TABLE.
+	 */
+	if (stmt->reset_default_tblspc)
+	{
+		save_nestlevel = NewGUCNestLevel();
+		(void) set_config_option("default_tablespace", "",
+								 PGC_USERSET, PGC_S_SESSION,
+								 GUC_ACTION_SAVE, true, 0, false);
+	}
 
 	/*
 	 * Start progress report.  If we're building a partition, this was already
@@ -622,10 +635,15 @@ DefineIndex(Oid relationId,
 	if (stmt->tableSpace)
 	{
 		tablespaceId = get_tablespace_oid(stmt->tableSpace, false);
+		if (partitioned && tablespaceId == MyDatabaseTableSpace)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot specify default tablespace for partitioned relation")));
 	}
 	else
 	{
-		tablespaceId = GetDefaultTablespace(rel->rd_rel->relpersistence);
+		tablespaceId = GetDefaultTablespace(rel->rd_rel->relpersistence,
+											partitioned);
 		/* note InvalidOid is OK in this case */
 	}
 
@@ -980,6 +998,13 @@ DefineIndex(Oid relationId,
 
 	ObjectAddressSet(address, RelationRelationId, indexRelationId);
 
+	/*
+	 * Revert to original default_tablespace.  Must do this before any return
+	 * from this function, but after index_create, so this is a good time.
+	 */
+	if (save_nestlevel >= 0)
+		AtEOXact_GUC(true, save_nestlevel);
+
 	if (!OidIsValid(indexRelationId))
 	{
 		table_close(rel, NoLock);