>On Tue, 2005-09-13 at 13:20, Warren Bell wrote: >> I am having problems with performance. I think this is a simple question and >> I am in the right place, if not, please redirect me. >> >> I have a table with 36 fields that slows down quite a bit after some light >> use. There are only 5 clients connected to this DB and they are doing mostly >> table has had no more than 10,000 records and is being accesessd at the rate >> of once per 5 seconds. It will slow down quite a bit. It will take 10 >> seconds to do a `SELECT * FROM` query. I delete all records except one >> perform a VACUUM and this will not speed it up. I drop the table and >> recreate it and insert one record and it speeds right back up takeing only >> 100 ms to do the query. > >This sounds like classic table / index bloat. > >Are you updating all 10,000 rows every 5 seconds? Good lord, that's a >lot of updates. If so, then do a vacuum immediately after the update >(or a delete), or change the system so it doesn't update every row every >time. > >Next time, try a vacuum full instead of a drop and recreate and see if >that helps. > >> >> I am fairly new to Postgres. What do I need to do to keep this table from >> slowing down? > >Vacuum this table more often. You might want to look at using the >autovacuum daemon to do this for you. > >You might want to post a little more info on what, exactly, you're doing >to see if we can spot any obvious problems. > >---------------------------(end of broadcast)--------------------------- >TIP 6: explain analyze is your friend I have three indexes on this table. One index is a 1 column, one index is a 5 column multi and one is a 2 column multi. I have run EXPLAIN ANALYZE on all of my queries and they seem to be taking advantage of these indexes. Would three indexes of this sort be considered "index bloat"? I am updating no more than 200 records at a time. Here are some examples of my queries: UPDATE table SET boolean_col_1 = true WHERE boolean_col_2 = false UPDATE table SET (several columns = something) WHERE char_col_1 = 'blah' AND int4_col_1 = 11 UPDATE table SET boolean_col_1 = true WHERE boolean_col_2 = false AND boolean_col_3 = false AND boolean_col_4 = false AND boolean_col_5 = false AND boolean_col_6 = false Is my use of indexes correct? In the meantime, I will start using autovacuum or VACUUM. Thanks for your help, ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
