On Tue, Sep 18, 2007 at 09:31:03AM -0700, Joshua D. Drake wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Tom Lane wrote: > > I wrote: > >> * The patch makes undocumented changes that cause autovacuum's decisions > >> to be driven by total estimated dead space rather than total number of > >> dead tuples. Do we like this? > > > If we do this, then it's not clear that having pgstats track dead space > > is worth the trouble at all. It might possibly be of value for testing > > purposes to see how well pruning is doing, but I'm unconvinced that it's > > worth bloating stats messages and files to have this number in a > > production system. An alternative that would serve as well for testing > > would be to teach contrib/pgstattuple to measure dead space. > > As a DBA, I can say it doesn't really matter to me *how we track* the > dead space, as long as tracking it is: > > 1. Clear > 2. Simple > 3. Available by default (thus pgstattuple needs to push into core) 3 isn't that important to me, but 4 is:
4. Doesn't hammer the database to measure And pgstattuple fails #4 miserably. Want to know the average dead space in a 500GB database? Yeah, right.... -- Decibel!, aka Jim C. Nasby, Database Architect [EMAIL PROTECTED] Give your computer some brain candy! www.distributed.net Team #1828
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