On Mon, May 13, 2013 at 6:01 PM, ach wrote:
what I'm wondering is, since
the unique constraint already covers the whole table and all rows in
entirety, is it really necessary for statistics to be set that high on
those?
AFAIK if there are exact-matching unique constraints/indexes for a
query's WHERE clause, the planner will deduce that the query only
returns 1 row and won't consult statistics at all.
Or does that only serve to slow down inserts to that table?
It doesn't slow down inserts directly. Tables are analyzed in the
background by autovacuum. However, I/O traffic from autovacuum analyze
may slow down inserts running concurrently.

Regards,
Marti

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postedMay 13, '13 at 3:01p
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