From: Martijn van Oosterhout <kleptog@svana.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Stephan Vollmer <svollmer@gmx.de>
Cc: pgsql-performance@postgreSQL.org
Subject: Re: [GENERAL] Creation of tsearch2 index is very slow
Date: Fri, 20 Jan 2006 22:37:54 +0100
Message-ID: <20060120213754.GG31908@svana.org> (raw)
In-Reply-To: <26958.1137791955@sss.pgh.pa.us>
References: <43D0ED57.1020608@gmx.de>
<17454.1137771321@sss.pgh.pa.us>
<20060120170452.GC31908@svana.org>
<26153.1137784469@sss.pgh.pa.us>
<20060120201036.GE31908@svana.org>
<26583.1137788505@sss.pgh.pa.us>
<20060120205132.GF31908@svana.org>
<26958.1137791955@sss.pgh.pa.us>
On Fri, Jan 20, 2006 at 04:19:15PM -0500, Tom Lane wrote:
> % cumulative self self total
> time seconds seconds calls Ks/call Ks/call name
> 98.96 1495.93 1495.93 33035195 0.00 0.00 hemdistsign
<snip>
> So we gotta fix hemdistsign ...
lol! Yeah, I guess so. Pretty nasty loop. LOOPBIT will iterate 8*63=504
times and it's going to do silly bit handling on each and every
iteration.
Given that all it's doing is counting bits, a simple fix would be to
loop over bytes, use XOR and count ones. For extreme speedup create a
lookup table with 256 entries to give you the answer straight away...
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.
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To: pgsql-performance@postgresql.org
Cc: kleptog@svana.org, tgl@sss.pgh.pa.us, svollmer@gmx.de
Subject: Re: [GENERAL] Creation of tsearch2 index is very slow
In-Reply-To: <20060120213754.GG31908@svana.org>
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