Re: [repost] partial index / funxtional idx or bad sql? - Mailing list pgsql-performance

From Josh Berkus
Subject Re: [repost] partial index / funxtional idx or bad sql?
Date
Msg-id 200305122032.10928.josh@agliodbs.com
Whole thread Raw
In response to Re: [repost] partial index / funxtional idx or bad sql?  (csajl <csajl@yahoo.com>)
Responses Re: [repost] partial index / funxtional idx or bad sql?
List pgsql-performance
Csajl,

> i'm using 7.3.2.  i tried using EXISTS instead of the IN, but the same
> query now returns in seven sceonds as opposed to four with the IN.
<snip>
> classifieds_dual_idx  is the btree index on (class_type_id, areacode)
> and site_cm_areacode_idx is the btree index on (site_id) only.
> there is an index in the areacode table that has both (site_id, areacode)
> but it's apparently not being used.  would it help the query to use that
> index instead?

No.
From the look of things, it's not the index scan that's taking time ... it's
the subplan, which is doing 61,000 loops.   Which is normal for IN, but not
for EXISTS.   You run VACUUM ANALYZE?

--
Josh Berkus
Aglio Database Solutions
San Francisco


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