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Re: [HACKERS] like/ilike improvements

From: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Patches (PostgreSQL)" <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [HACKERS] like/ilike improvements
Date: 2007-06-01 05:07:29
Message-ID: 20070601134851.8C2D.ITAGAKI.TAKAHIRO@oss.ntt.co.jp (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:

> OK, here is a patch that I think incorporates all the ideas discussed 
> (including part of Mark Mielke's suggestion about optimising %_). There 
> is now no special treatment of UTF8 other than its use of a faster 
> NextChar macro.

This is a benchmark result of 1000 loops of 
  SELECT count(*) INTO cnt FROM item WHERE i_title LIKE '%BABABABABARIBA%'
on the table with 10000 rows.

         | SQL_ASCII | LATIN1 |  UTF8 | EUC_JP 
---------+-----------+--------+-------+---------
 HEAD    |      8017 |   8029 | 16928 |  18213 
 Patched |      7899 |   7887 |  9985 |  10370 [ms]

It improved the performance not only for UTF8, but also for other
multi-byte encodings and a bit for single-byte encodings.

Thanks for the good work ;)

---
ITAGAKI Takahiro
NTT Open Source Software Center



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