Re: Unused index influencing sequential scan plan

From: Peter Geoghegan <peter(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Thom Brown <thom(at)linux(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Unused index influencing sequential scan plan
Date: 2012-10-18 17:00:43
Message-ID: CAEYLb_UD3jmHyCTnfrfywcNG5A4aSt9X8X+9TTVojdxgW4Asnw@mail.gmail.com
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On 18 October 2012 17:52, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I forgot to mention that there is a klugy workaround: add the required
> variable(s) as extra index columns. That is,
>
> create index i on t (foo(x), x);

Is there a case to be made for a index access method whose
pseudo-indexes costs essentially nothing to maintain, and simply
represent an ongoing obligation for ANALYZE to provide statistics for
an expression?

--
Peter Geoghegan http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services

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