Re: [HACKERS] like/ilike improvements - Mailing list pgsql-patches

Andrew Dunstan <andrew@dunslane.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 ;)

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ITAGAKI Takahiro
NTT Open Source Software Center