Re: [HACKERS] like/ilike improvements

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 ;)

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ITAGAKI Takahiro
NTT Open Source Software Center