Re: Strange Create Index behaviour
Gary Doades <gpd@gpdnet.co.uk>
From: Gary Doades <gpd@gpdnet.co.uk>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Date: 2006-02-15T21:34:11Z
Lists: pgsql-hackers, pgsql-performance
Tom Lane wrote: > I tried forcing PG to use src/port/qsort.c on the Fedora machine, > and lo and behold: > new Fedora 4 machine: shortest 434 msec, longest 8530 msec > > So it sure looks like this script does expose a problem on BSD-derived > qsorts. Curiously, the case that's much the worst for me is the third > in the script, while the shortest time is the first case, which was slow > for Gary. So I'd venture that the *BSD code has been tweaked somewhere > along the way, in a manner that moves the problem around without really > fixing it. (Anyone want to compare the actual FreeBSD source to what > we have?) > If I run the script again, it is not always the first case that is slow, it varies from run to run, which is why I repeated it quite a few times for the test. Interestingly, if I don't delete the table after a run, but just drop and re-create the index repeatedly it stays a pretty consistent time, either repeatedly good or repeatedly bad! Regards, Gary.