Re: Performance of query (fwd)

From: Edmund Dengler <edmundd(at)eSentire(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Performance of query (fwd)
Date: 2003-06-11 20:06:04
Message-ID: Pine.BSO.4.44.0306111602340.15310-100000@cyclops4.esentire.com
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Whoops! Thanks! Tried it, and it did return very fast (about a second and
a half). Things switched from a "merge join" to a "nested loop".

Regards,
Ed

On Wed, 11 Jun 2003, Tom Lane wrote:

> Edmund Dengler <edmundd(at)eSentire(dot)com> writes:
> > Ok, tried it with a constant. No improvements. The estimator is still very
> > high.
>
> > where timestamp > '2003-06-11 9:22 EDT'::timestamp
>
> > -> Index Scan using timestamp_idx on event (cost=0.00..557630.23 rows=237136 width=24) (actual time=0.22..16.58 rows=139 loops=1)
> > Index Cond: ("timestamp" > ('2003-06-11 09:22:00'::timestamp without time zone)::timestamp with time zone)
>
> It would probably help if you cast the constant to the same datatype
> as the column is (which is evidently timestamp with time zone).
> Coercions between timestamp and timestamptz are not considered
> constants, because they depend on SET TIMEZONE.
>
> regards, tom lane
>

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