From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Sven R. Kunze" <srkunze@tbz-pariv.de>
cc: pgsql-performance@postgresql.org
Subject: Re: Reverse Key Index
In-reply-to: <54DF9036.8080502@tbz-pariv.de>
References: <54DF9036.8080502@tbz-pariv.de>
Comments: In-reply-to "Sven R. Kunze" <srkunze@tbz-pariv.de>
 message dated "Sat, 14 Feb 2015 19:13:10 +0100"
Date: Sat, 14 Feb 2015 13:18:19 -0500
Message-ID: <7978.1423937899@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

"Sven R. Kunze" <srkunze@tbz-pariv.de> writes:
> does PostgreSQL support the concept of reverse key indexing as described 
> here? I couldn't find any documentation on this yet.

> http://www.toadworld.com/platforms/oracle/w/wiki/11075.reverse-key-index-from-the-concept-to-internals.aspx

There's nothing built-in for that (and frankly, it doesn't sound useful
enough that we'd ever add it).  You could get the effect easily enough
with an expression index on a byte-reversing function.  A related thing
that people often do is create an index on a hash function.

			regards, tom lane


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