Re: [pgsql-hackers-win32] Help with tuning this query (with explain analyze finally)
"Dave Held" <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.performance,gmane.comp.db.postgresql.devel.win32 |
|---|---|
| Message-ID | <[email protected]> |
> -----Original Message----- > From: Tom Lane [mailto:[email protected]] > Sent: Monday, March 07, 2005 10:39 AM > To: John A Meinel > Cc: Magnus Hagander; Ken Egervari; [email protected]; > [email protected] > Subject: Re: [pgsql-hackers-win32] [PERFORM] Help with tuning > this query > (with explain analyze finally) > > [...] > The EXPLAIN ANALYZE instrumentation code will really be happier with a > straight time-since-bootup counter; by using gettimeofday, it is > vulnerable to giving wrong answers if someone changes the date setting > while the EXPLAIN is running. But there is (AFAIK) no such call among > the portable Unix syscalls. It seems reasonable to me to #ifdef that > code to make use of QueryPerformanceCounter on Windows. This does not > mean we want to alter the behavior of gettimeofday() where it's being > used to find out the time of day. There is always clock(). It's mandated by ANSI C, but my docs say that POSIX requires CLOCKS_PER_SEC == 1000000 regardless of actual timer resolution, which seems a little brain-dead to me. __ David B. Held Software Engineer/Array Services Group 200 14th Ave. East, Sartell, MN 56377 320.534.3637 320.253.7800 800.752.8129 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq