On Sep 17, 2008, at 9:30 AM, Heikki Linnakangas wrote:
I think we'd still need to WAL log operations that decrease the amount of free space on page. Otherwise, after we have partial vacuum, we might never revisit a page, and update the FSM, even though there's usable space on the page, leaving the space forgotten forever.
ISTM that it would be better to deal with such corner cases via periodic non-partial vacuums, done by something like autovac, and probably done with an ever higher-than-normal vacuum_cost_delay setting so as to minimize performance. That's likely a lot less wasteful than further compounding lock contention for the WAL. Even if it does result in more overall IO, you have to trade a *lot* of IO to balance out the impact of lock contention.
-- Decibel!, aka Jim C. Nasby, Database Architect [EMAIL PROTECTED] Give your computer some brain candy! www.distributed.net Team #1828
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