Re: char() overhead on read-only workloads not so insignifcant as the docs claim it is...
| От | Alvaro Herrera |
|---|---|
| Тема | Re: char() overhead on read-only workloads not so insignifcant as the docs claim it is... |
| Дата | |
| Msg-id | 20090615235816.GO7285@alvh.no-ip.org обсуждение исходный текст |
| Ответ на | Re: char() overhead on read-only workloads not so insignifcant as the docs claim it is... (Gurjeet Singh <singh.gurjeet@gmail.com>) |
| Ответы |
Re: char() overhead on read-only workloads not so insignifcant as the docs claim it is...
[PATCH] backend: compare word-at-a-time in bcTruelen |
| Список | pgsql-hackers |
> On Sat, Jun 13, 2009 at 3:44 PM, Stefan Kaltenbrunner > <stefan@kaltenbrunner.cc> wrote: > > The specific query is causing bcTruelen to show up in the profile is: > > > > "SELECT c from sbtest where id between $1 and $2 order by c" where the > > parameters are for example > > $1 = '5009559', $2 = '5009658' - ie ranges of 100. > > > > > > benchmarking only that query results in: > > > > samples % symbol name > > 2148182 23.5861 bcTruelen > > 369463 4.0565 index_getnext > > 362784 3.9832 AllocSetAlloc Gurjeet Singh escribió: > Comments? Maybe bcTruelen could be optimized to step on one word at a time (perhaps by using XOR against a precomputed word filled with ' '), instead of one byte at a time ... -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.
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