My understanding is that having NULL values in an index breaks it completely. Meaning it won't be used in any query planning. Maybe I'm wrong though...
-----Original Message----- From: Marinos J. Yannikos [mailto:[EMAIL PROTECTED] Sent: Tue 1/27/2004 12:26 PM To: [EMAIL PROTECTED] Cc: Subject: [PERFORM] (partial?) indexes, LIKE and NULL Hi, with the following table: Table "public.foo" Column | Type | Modifiers --------+------+----------- t | text | Indexes: "a" btree (t) Shouldn't queries that use ... where t like '%something%' benefit from "a" when t is NULL in almost all cases, since the query planner could use "a" to access the few non-NULL rows quickly? It doesn't seem to work right now. (I assume that it would make no difference if the index "a" was partial, excluding NULLs) Regards, -mjy ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
