From: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
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To: | Peter Geoghegan <pg(at)heroku(dot)com> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: ICU integration |
Date: | 2017-01-09 20:25:36 |
Message-ID: | 6261dcf6-5bd1-a4ce-a800-54b34d696b3e@2ndquadrant.com |
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Lists: | pgsql-hackers |
On 1/7/17 10:01 PM, Peter Geoghegan wrote:
> It occurs to me that the comparison caching stuff added by commit
> 0e57b4d8b needs to be considered here, too. When we had to copy the
> string to a temp buffer anyway, in order to add the terminating NUL
> byte expected by strcoll(), there was an opportunity to do caching of
> comparisons at little additional cost. However, since ICU offers an
> interface that you're using that doesn't require any NUL byte, there
> is a new trade-off to be considered -- swallow the cost of copying
> into our own temp buffer solely for the benefit of comparison caching,
> or don't do comparison caching. (Note that glibc had a similar
> comparison caching optimization itself at one point, built right into
> strcoll(), but it was subsequently disabled.)
That might be worth looking into, but it seems a bit daunting to
construct a benchmark specifically for this, unless we have the one that
was originally used lying around somewhere.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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