| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> |
| Subject: | Re: char() overhead on read-only workloads not so insignifcant as the docs claim it is... |
| Date: | 2009-06-15 23:58:16 |
| Message-ID: | 20090615235816.GO7285@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-hackers |
> On Sat, Jun 13, 2009 at 3:44 PM, Stefan Kaltenbrunner
> <stefan(at)kaltenbrunner(dot)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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