On Wed, Aug 08, 2007 at 11:01:13AM -0400, Steve Madsen wrote: > Can anyone provide a brief overview of how to go about interpreting > the information generated by the statistics collector? I've looked > around and can't find old mailing list messages or anything in the > manual beyond the basics of how to query the statistics. > > Cache hit rates are easy to compute, but is this useful beyond > knowing if Postgres has enough buffers? > > Can anything useful be gleaned from looking at idx_scan / > idx_tup_read / idx_tup_fetch? Yes, that will give you information about how often an index is being used. If you see indexes where idx_scan is a small number, that's an indication that that index isn't being used for queries and could potentially be dropped. Something else I like to look at is pg_stat_all_tables seq_scan and seq_tup_read. If seq_scan is a large number and seq_tup_read/seq_scan is also large, that indicates that you could use an index on that table. -- Decibel!, aka Jim Nasby decibel@xxxxxxxxxxx EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
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