Re: Why isn't an index scan being used? - Mailing list pgsql-performance

From Jeff Janes
Subject Re: Why isn't an index scan being used?
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Msg-id CAMkU=1zrAsD4apC3rED+O7BuFL_82tL6LYNGTMfqAyWQ1D0LBw@mail.gmail.com
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In response to Re: Why isn't an index scan being used?  (Abi Noda <a@abinoda.com>)
List pgsql-performance

On Tue, Feb 19, 2019 at 11:59 PM Abi Noda <a@abinoda.com> wrote:
Thanks Justin.

The 4ms different in the examples isn't an accurate benchmark. I'm seeing about a ~20% difference over a larger sample size. And this is on a fork of the production database.

Please show the execution plans from that larger sample, if that is the one that is most relevant.

You can "set enable_bitmapscan = off" to get rid of the bitmap scan in order to see the estimated cost and actual performance of the next-best plan (which will probably the regular index scan).

Cheers,

Jeff

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