Re: POSIX regex performance bug in 7.3 Vs. 7.2

From: wade <wade(at)wavefire(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: POSIX regex performance bug in 7.3 Vs. 7.2
Date: 2003-02-04 00:37:28
Message-ID: 3.0.32.20030203163728.01f16a40@mail.wavefire.com
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At 05:51 PM 2/3/03 -0500, Tom Lane wrote:
>wade <wade(at)wavefire(dot)com> writes:
>> Here is the profile information. I included a log of the session that
>> generated it at the top of the gprof output. If there is any other info I
>> can help you with, please let me know.
>
>A four-second test isn't long enough to gather any statistically
>meaningful profile info. On most machines, gprof samples 100 times per
>second, so realistically you need a minute or two of runtime to have
>trustworthy numbers.
>
>Please replicate the rows in the table by a factor of ten or twenty or
>so and try again.
>
> regards, tom lane
OK, here goes again.
I have tried a different table, this one with 27444 rows.
In this case, the query with the regex of the form "row ~* 'regex'"
runs in 1.113 seconds and the other runs in 600.
The session idled for a while after the query completed if that makes a
difference.
Queries and explain output are included at the top of the gprof output.
http://arch.wavefire.com/pgregexgmon.txt
-Wade Klaver

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