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 code to
tweak existing (and more importantly working) queries to hash/reverse an
id column first. Using ORMs would make this change even more painful and
maybe even impossible.
When reading
https://richardfoote.wordpress.com/2008/01/14/introduction-to-reverse-key-indexes-part-i/
carefully, it also seems to work with index scan partially in case of
equality comparisons.
On 14.02.2015 19:18, Tom Lane wrote:
"Sven R. Kunze" <srkunze@xxxxxxxxxxxx> 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
--
Sven R. Kunze
TBZ-PARIV GmbH, Bernsdorfer Str. 210-212, 09130 Chemnitz
Tel: +49 (0)371 33714721, Fax: +49 (0)371 5347920
e-mail: srkunze@xxxxxxxxxxxx
web: www.tbz-pariv.de
Geschäftsführer: Dr. Reiner Wohlgemuth
Sitz der Gesellschaft: Chemnitz
Registergericht: Chemnitz HRB 8543
--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
