Re: Performace question
От | Lada 'Ray' Lostak |
---|---|
Тема | Re: Performace question |
Дата | |
Msg-id | 016c01c39e50$9e6b24a0$0d01a8c0@utopia обсуждение исходный текст |
Ответ на | Performace question ("Lada 'Ray' Lostak" <ray@unreal64.net>) |
Список | pgsql-general |
> > >Secondly, the queries that are varying so much, can you post the EXPLAIN > > >ANALYZE output so we can see what is actually going on. > > Thx, ANALYZE was good idea. Here it comes - right now, there is index on > > 'cluster' (BTREE) @ dtditems. But it was not used - I guess because reading > > & seraching will cost more than pure seq scan on 'few' items... > > Hmm... have you tried running VACUUM periodically? Sure.... But I will try 'full'.... Joy ! You hit the right problem... Thank you ! Seq Scan on dtditems (cost=0.00..16.40 rows=113 width=82) (actual time=0.78..3.30 rows=113 loops=1) Filter: ("cluster" = 42) Total runtime: 3.84 msec It required 'full' vacuum.. My bad I guess.... Now is the execution time 'constant' :) ps: my MAJOR problem was: WHY are execution time soo different ? 4 sequential execs: Seq Scan on dtditems (cost=0.00..253.40 rows=150 width=84) (actual time=1534.52..1566.37 rows=113 loops=1) Filter: ("cluster" = 42) Total runtime: 1566.95 msec Seq Scan on dtditems (cost=0.00..253.40 rows=150 width=84) (actual time=29.27..32.29 rows=113 loops=1) Filter: ("cluster" = 42) Total runtime: 32.81 msec Seq Scan on dtditems (cost=0.00..253.40 rows=150 width=84) (actual time=1695.69..1735.83 rows=113 loops=1) Filter: ("cluster" = 42) Total runtime: 1736.36 msec Seq Scan on dtditems (cost=0.00..253.40 rows=150 width=84) (actual time=29.27..32.29 rows=113 loops=1) Filter: ("cluster" = 42) Total runtime: 53.12 msec Any hint why there was this difference ? R.
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