Re: bigint indices with inequalities?

From: "Ed L(dot)" <pgsql(at)bluepolka(dot)net>
To: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
Cc: PostgreSQL general list <pgsql-general(at)postgresql(dot)org>
Subject: Re: bigint indices with inequalities?
Date: 2003-03-19 02:00:45
Message-ID: 200303181900.45537.pgsql@bluepolka.net
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On Tuesday March 18 2003 6:16, Stephan Szabo wrote:
> On Tue, 18 Mar 2003, Ed L. wrote:
> > Can anyone help me understand why this query is not using an index?
> > Schema, query, and explain output for 3 different attempts are below.
> >
...
> > -> Seq Scan on _dbm_pending_data pd (cost=0.00..886.74
...
> > -> Seq Scan on _dbm_pending p
> > (cost=0.00..832.93 rows=35876 width=46)
> > Filter: (xid > 268010::bigint)
>
> It's estimating that the xid condition is not very selective (35876 of
> 36474). If that's true an index scan is likely to be a loser against the
> sequence scan.

That makes perfect sense. Turns out the literal was very near the minimum
value. Thanks.

Ed

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