| From: | John Naylor <john(dot)naylor(at)enterprisedb(dot)com> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
| Subject: | Re: speed up text_position() for utf-8 |
| Date: | 2021-12-15 16:43:37 |
| Message-ID: | CAFBsxsGAcmsHFsiNh=TywjkwOgebbT87hsrPRkgf-b=HLO=vjA@mail.gmail.com |
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| Lists: | pgsql-hackers |
I wrote:
> The test is attached and the test function is part of the patch. It's
> based on the test used in the commit above. The test searches for a
> string that's at the end of a ~1 million byte string. This is on gcc
> 11 with 2-3 runs to ensure repeatability, but I didn't bother with
> statistics because the differences are pretty big:
>
> patch | no match | ascii | mulitbyte
> -----------------------------------------+----------+-------+-----------
> PG11 | 1120 | 1100 | 900
> master | 381 | 2350 | 1900
> DFA | 386 | 1640 | 1640
> branchless utf mblen | 387 | 4100 | 2600
> inline pg_utf_mblen() | 380 | 1080 | 920
> inline pg_utf_mblen() + ascii fast path | 382 | 470 | 918
I failed to mention that the above numbers are milliseconds, so
smaller is better.
--
John Naylor
EDB: http://www.enterprisedb.com
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