From: | Filip Rembiałkowski <plk(dot)zuber(at)gmail(dot)com> |
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To: | Tyler Hains <thains(at)profitpointinc(dot)com> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Query Optimizer makes a poor choice |
Date: | 2011-11-29 19:16:27 |
Message-ID: | CAP_rwwkE8pGhGsOXt2LQgE9K9_B4LRaLe7=0pT3ZdRQYeEPixQ@mail.gmail.com |
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2011/11/29 Tyler Hains <thains(at)profitpointinc(dot)com>:
> # explain analyze select * from cards where card_set_id=2850 order by
> card_id limit 1;
> QUERY PLAN
> -----------------------------------------------------------------------------------------------------------------------------------------
> Limit (cost=0.00..105.19 rows=1 width=40) (actual time=6026.947..6026.948
> rows=1 loops=1)
> -> Index Scan using cards_pkey on cards (cost=0.00..2904875.38
> rows=27616 width=40) (actual time=6026.945..6026.945 rows=1 loops=1)
> Filter: (card_set_id = 2850)
> Total runtime: 6026.985 ms
do you have autovacum enabled?
does the plan change when you push stats target for this column?
ALTER TABLE cards ALTER card_set_id SET STATISTICS 500;
ANALYZE cards ( card_set_id );
what happens when you do:
select * from ( select * from cards where card_set_id=2850 ) order by
card_id limit 1
?
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