index scans, reads, fetches

We're pulling a number of metrics for a client to help tune their database, and we had some questions about the stats coming from pg_stat_user_indexes.  Namely, what do we want the growth (when looking at interval values) of idx_scan, idx_tup_read, and idx_tup_fetch to look like and how do we tune them?
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Samuel Nelson
Consistent State
www.consistentstate.com
303-955-0509
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