On Aug 8, 2007, at 6:08 PM, Decibel! wrote:
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.
If seq_tup_read / seq_scan is large relative to the number of rows in
the table, wouldn't that imply that those sequential scans are often
returning most of the rows in the table? In that case, would an
index help much or is a sequential scan the expected result?
--
Steve Madsen <steve@xxxxxxxxxxxxxxxxxxxxx>
Light Year Software, LLC http://lightyearsoftware.com
ZingLists: Stay organized, and share lists online. http://zinglists.com
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
