Message-ID: <54F81F3F.3010607@tbz-pariv.de>
Date: Thu, 05 Mar 2015 10:17:51 +0100
From: "Sven R. Kunze" <srkunze@tbz-pariv.de>
Organization: TBZ-PARIV GmbH
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To: hlinnaka@iki.fi, Josh Berkus <josh@agliodbs.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-performance@postgresql.org
Subject: Re: Reverse Key Index
References: <54DF9036.8080502@tbz-pariv.de> <7978.1423937899@sss.pgh.pa.us>
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 <54EE4D45.1060704@agliodbs.com> <54EF1370.2000006@iki.fi>
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On 26.02.2015 13:37, Heikki Linnakangas wrote:
> On 02/26/2015 12:31 AM, Josh Berkus wrote:
>> On 02/14/2015 10:35 AM, Sven R. Kunze wrote:
>>> Thanks for the immediate reply.
>>>
>>> I understand the use case is quite limited.
>>>
>>> On the other hand, I see potential when it comes to applications which
>>> use PostgreSQL. There, programmers would have to change a lot of=20
>>> code to
>>> tweak existing (and more importantly working) queries to=20
>>> hash/reverse an
>>> id column first. Using ORMs would make this change even more painful=20
>>> and
>>> maybe even impossible.
>>>
>>> When reading
>>> https://richardfoote.wordpress.com/2008/01/14/introduction-to-reverse-k=
ey-indexes-part-i/=20
>>>
>>> carefully, it also seems to work with index scan partially in case of
>>> equality comparisons.
>>
>> Seems like a good use for SP-GiST.  Go for it!
>
> A b-tree opclass that just compares from right-to-left would work just
> as well, and perform better.
>
> - Heikki
>


Thanks for the hint. That also sounds easy to implement.

Regards,

--=20
Sven R. Kunze
TBZ-PARIV GmbH, Bernsdorfer Str. 210-212, 09126 Chemnitz
Tel: +49 (0)371 33714721, Fax: +49 (0)371 5347920
e-mail: srkunze@tbz-pariv.de
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--=20
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