On Fri, Jun 24, 2011 at 12:51 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 24.06.2011 11:40, Heikki Linnakangas wrote: >> >> On 21.06.2011 13:08, Alexander Korotkov wrote: >>> >>> I believe it's due to relatively expensive penalty >>> method in that opclass. >> >> Hmm, I wonder if it could be optimized. I did a quick test, creating a >> gist_trgm_ops index on a list of English words from >> /usr/share/dict/words. oprofile shows that with the patch, 60% of the >> CPU time is spent in the makesign() function. > > I couldn't resist looking into this, and came up with the attached patch. I > tested this with: > > CREATE TABLE words (word text); > COPY words FROM '/usr/share/dict/words'; > CREATE INDEX i_words ON words USING gist (word gist_trgm_ops); > > And then ran "REINDEX INDEX i_words" a few times with and without the patch. > Without the patch, reindex takes about 4.7 seconds. With the patch, 3.7 > seconds. That's a worthwhile gain on its own, but becomes even more > important with Alexander's fast GiST build patch, which calls the penalty > function more. > > I used the attached showsign-debug.patch to verify that the patched makesign > function produces the same results as the existing code. I haven't tested > the big-endian code, however.
Out of curiosity (and because there is no comment or Assert here), how can you be so sure of the input alignment? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
