On Apr 29, 2008, at 10:16 AM, Tom Lane wrote:
Greg Smith <[EMAIL PROTECTED]> writes:
The model here assumes that you'll need that space again for the
next time
you UPDATE or INSERT a row. So instead VACUUM just keeps those
available
for database reuse rather than returning it to the operating system.
[ ... ]
Also, you need to make sure you have the FSM parameters set high
enough
so that all the free space found by a VACUUM run can be remembered.
The less often you run VACUUM, the more FSM space you need, because
there'll be more free space reclaimed per run.
I can actually watch one of our applications slow down once the free
space in the table is used up. Extending the data file seems to be
much more expensive than using the free space found in existing pages
of the file.
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