Re: seqscan for 100 out of 3M rows, index present

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To: Jeff Janes <jeff.janes@xxxxxxxxx>
Subject: Re: seqscan for 100 out of 3M rows, index present
From: Willy-Bas Loos <willybas@xxxxxxxxx>
Date: Wed, 26 Jun 2013 22:36:10 +0200
Cc: Scott Marlowe <scott.marlowe@xxxxxxxxx>, "pgsql-performance@xxxxxxxxxxxxxx" <pgsql-performance@xxxxxxxxxxxxxx>
In-reply-to: <CAMkU=1xzMULy-Ag=h_XK12MhnDtX=qus5YuiO1UV_TQ-c=dL9A@mail.gmail.com>
References: <CAHnozTgJQq8vPns_WpS+7i=JrQm9zaCyQ_-eKD2HzCibfSZ1Qw@mail.gmail.com> <CAOR=d=1gosvUcpxcqEk39ASuxPS2ngBmuP+V+rPjvSJui3=6Rw@mail.gmail.com> <CAMkU=1xzMULy-Ag=h_XK12MhnDtX=qus5YuiO1UV_TQ-c=dL9A@mail.gmail.com>

On Wed, Jun 26, 2013 at 10:31 PM, Jeff Janes <jeff.janes@xxxxxxxxx> wrote:

Why is it retrieving 3.1 million, when it only needs 17?

that's because of the sequential scan, it reads all the data.

cheers,

willy-bas

--
"Quality comes from focus and clarity of purpose" -- Mark Shuttleworth

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