| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Stephan Vollmer <svollmer(at)gmx(dot)de>, pgsql-performance(at)postgreSQL(dot)org |
| Subject: | Re: [GENERAL] Creation of tsearch2 index is very slow |
| Date: | 2006-01-20 21:37:54 |
| Message-ID: | 20060120213754.GG31908@svana.org |
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| Lists: | pgsql-general pgsql-performance |
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(at)svana(dot)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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