On Tue, May 09, 2006 at 01:29:56PM +0200, PFC wrote: > 0.101 ms BEGIN > 1.451 ms CREATE TEMPORARY TABLE tmp ( a INTEGER NOT NULL, b INTEGER NOT > NULL, c TIMESTAMP NOT NULL, d INTEGER NOT NULL ) ON COMMIT DROP > 0.450 ms INSERT INTO tmp SELECT * FROM bookmarks ORDER BY annonce_id DESC > LIMIT 20 > 0.443 ms ANALYZE tmp > 0.365 ms SELECT * FROM tmp > 0.310 ms DROP TABLE tmp > 32.918 ms COMMIT > > CREATING the table is OK, but what happens on COMMIT ? I hear the > disk seeking frantically. > > With fsync=off, I get this : > > 0.090 ms BEGIN > 1.103 ms CREATE TEMPORARY TABLE tmp ( a INTEGER NOT NULL, b INTEGER NOT > NULL, c TIMESTAMP NOT NULL, d INTEGER NOT NULL ) ON COMMIT DROP > 0.439 ms INSERT INTO tmp SELECT * FROM bookmarks ORDER BY annonce_id DESC > LIMIT 20 > 0.528 ms ANALYZE tmp > 0.364 ms SELECT * FROM tmp > 0.313 ms DROP TABLE tmp > 0.688 ms COMMIT > > Getting closer ? > I'm betting on system catalogs updates. I get the same timings with > ROLLBACK instead of COMMIT. Temp tables have a row in pg_class... Have you tried getting a profile of what exactly PostgreSQL is doing that takes so long when creating a temp table? BTW, I suspect catalogs might be the answer, which is why Oracle has you define a temp table once (which does all the work of putting it in the catalog) and then you just use it accordingly in each individual session. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
