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Re: Unused index influencing sequential scan plan - Mailing list pgsql-performance

From Peter Geoghegan
Subject Re: Unused index influencing sequential scan plan
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Msg-id CAEYLb_XP7UEPdCwypJi97dcvgdpSBzoK0Rym1nmTp1Z5TtegFg@mail.gmail.com
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In response to Unused index influencing sequential scan plan  (Thom Brown <thom@linux.com>)
Responses Re: Unused index influencing sequential scan plan
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On 18 October 2012 17:11, Thom Brown <thom@linux.com> wrote:
> The estimate is down to almost a 10th of what it was before.  What's going on?

Even though the index isn't used, the pg_statistic entries that the
expression index would have made available are. It's as if you
materialised the expression into a column, analyzed and grouped by
that.

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

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