[Just a quick note here; a more thorough discussion of my test results will be posted to -hackers]
On Tue, 13 Apr 2004 15:18:42 -0400, Tom Lane <[EMAIL PROTECTED]> wrote: >Well, the first problem is why is ANALYZE's estimate of the total row >count so bad :-( ? I suspect you are running into the situation where >the initial pages of the table are thinly populated and ANALYZE >mistakenly assumes the rest are too. Manfred is working on a revised >sampling method for ANALYZE that should fix this problem The new method looks very promising with respect to row count estimation: I got estimation errors of +/- 1% where the old method was off by up to 60%. (My test methods might be a bit biased though :-)) My biggest concern at the moment is that the new sampling method violates the contract of returning each possible sample with he same probability: getting several tuples from the same page is more likely than with the old method. Servus Manfred ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly