From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
To: Josh Berkus <josh@agliodbs.com>
To: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Strange choice of general index over partial index
Date: Fri, 16 Jan 2015 16:17:12 +1300
Message-ID: <54B882B8.2050303@catalyst.net.nz> (raw)
In-Reply-To: <54B88032.7020206@catalyst.net.nz>
References: <54B83F70.7080004@agliodbs.com>
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<54B87820.3090101@catalyst.net.nz>
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On 16/01/15 16:06, Mark Kirkwood wrote:
> A bit more poking about shows that the major factor (which this fake
> dataset anyway) is the default for effective_cache_size (changes from
> 128MB to 4GB in 9.4). Increasing this makes 9.2 start using the
> files_in_flight index in a plain index scan too.
>
Arrg - misread the planner output....in 9.2 what changes is a plan that
uses an index scan on the *file_state* index (not
files_in_flight)...which appears much faster than the bitmap scan on
file_state. Apologies for the confusion.
I'm thinking that I'm seeing the effect Tom has just mentioned.
regards
Mark
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To: pgsql-performance@postgresql.org
Cc: mark.kirkwood@catalyst.net.nz, josh@agliodbs.com
Subject: Re: Strange choice of general index over partial index
In-Reply-To: <54B882B8.2050303@catalyst.net.nz>
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