Thanks to Luke and Tom for the input. I guess this was good timing
given that it looks like
8.2 was just released today. I will upgade to that before doing
anything else.
Glenn
Tom Lane wrote:
Glenn Sullivan <[EMAIL PROTECTED]> writes:
I am wanting some ideas about improving the performance of ORDER BY in
our use. I have a DB on the order of 500,000 rows and 50 columns.
The results are always sorted with ORDER BY. Sometimes, the users end up
with a search that matches most of the rows. In that case, I have a
LIMIT 5000 to keep the returned results under control. However, the
sorting seems to take 10-60 sec. If I do the same search without the
ORDER BY, it takes about a second.
Does the ORDER BY match an index? If so, is it using the index?
(See EXPLAIN.)
I am currently on version 8.0.1 on Windows XP using a Dell Optiplex 280
with 1Gb of ram. I have set sort_mem=100000 set.
In 8.0 that might be counterproductively high --- we have seen cases
where more sort_mem = slower with the older sorting code. I concur
with Luke's advice that you should update to 8.2 (not 8.1) to get the
improved sorting code.
regards, tom lane
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