Re: [PERFORM] The usual sequential scan, but with LIMIT !
Pierre-Frédéric Caillaud wrote: Yes, you're right as usual. As usual ? Do you think your father can be wrong on you ? :-) Gaetano ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] The usual sequential scan, but with LIMIT !
Yes, you're right as usual. I had not thought about playing with ORDER BY on a field which has only one value in the result set. If you write it as SELECT WHERE topic_id=2 ORDER BY topic_id DESC,id DESC. then an index on (topic_id, id) will work fine. The mixed ASC/DESC ordering is not compatible with the index. ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] [ADMIN] TOAST tables, cannot truncate
G u i d o B a r o s i o <[EMAIL PROTECTED]> writes: > Ok, problem solved. > A previous ALTER TABLE DROP COLUMN over this table was performed. > By some reason, truncate didn't work then. Would like to know why...it does not > seems to be a very frequent problem, due to the fact I only found one chat on the > mailing lists talking about this issue, and was hard to find :( ! http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/cluster.c (note: cvsweb seems mighty slow today, but it is working...) regards, tom lane ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [PERFORM] The usual sequential scan, but with LIMIT !
=?iso-8859-15?Q?Pierre-Fr=E9d=E9ric_Caillaud?= <[EMAIL PROTECTED]> writes: > suppose I SELECT WHERE topic_id=2 ORDER BY topic_id ASC,id DESC. > Postgres does a seq scan, but it could think a bit more and start at > "first index node which has topic_id>2" (simple to find in a btree) then > go backwards in the index. If you write it as SELECT WHERE topic_id=2 ORDER BY topic_id DESC,id DESC. then an index on (topic_id, id) will work fine. The mixed ASC/DESC ordering is not compatible with the index. regards, tom lane ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
Re: [PERFORM] [ADMIN] TOAST tables, cannot truncate
Ok, problem solved. A previous ALTER TABLE DROP COLUMN over this table was performed. By some reason, truncate didn't work then. Would like to know why...it does not seems to be a very frequent problem, due to the fact I only found one chat on the mailing lists talking about this issue, and was hard to find :( ! A dump of the table schema, passed to the psql command (cat table_dump.sql | psql xxx) worked fine. TRUNCATE is now available. Thanks. Guido > Sorry for crossposting, didn't know where to post. > > Any hint/help on this?! > > db_postgres1=# truncate ref_v2_drs_valid_product ; > ERROR: expected both swapped tables to have TOAST tables > > I need to truncate this table, this is the first time I see this error. > > Regards, > Guido > > > ---(end of broadcast)--- > TIP 8: explain analyze is your friend ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
[PERFORM] TOAST tables, cannot truncate
Sorry for crossposting, didn't know where to post. Any hint/help on this?! db_postgres1=# truncate ref_v2_drs_valid_product ; ERROR: expected both swapped tables to have TOAST tables I need to truncate this table, this is the first time I see this error. Regards, Guido ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
