Gan,
> Oh, so in order to reclaim the disk space, we must run
> reindex or vacuum full ?
> This will lock out the table and we won't be able to do anything.
> Looks like this is a problem. It means we cannot use it for
> 24x7 operations without having to stop the process and do the vacuum full
> and reindex. Is there anything down the road that these operations
> will not lock out the table ?
I doubt it; the amount of page-shuffling required to reclaim 90% of the space
in an index for a table that has been mostly cleared is substantial, and
would prevent concurrent access.
Also, you seem to have set up an impossible situation for VACUUM. If I'm
reading your statistics right, you have a large number of threads accessing
most of the data 100% of the time, preventing VACUUM from cleaning up the
pages. This is not, in my experience, a realistic test case ... there are
peak and idle periods for all databases, even webservers that have been
slashdotted.
--
Josh Berkus
Aglio Database Solutions
San Francisco