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Re: planner with index scan cost way off actual cost, - Mailing list pgsql-performance

From Simon Riggs
Subject Re: planner with index scan cost way off actual cost,
Date
Msg-id 1142974647.24487.518.camel@localhost.localdomain
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In response to planner with index scan cost way off actual cost, advices to tweak cost constants?  (Guillaume Cottenceau <gc@mnc.ch>)
List pgsql-performance
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On Fri, 2006-03-17 at 11:09 +0100, Guillaume Cottenceau wrote:

> INFO:  index "idx_sent_msgs_date_theme_status" now contains 3692284 row versions in 88057 pages

> SET effective_cache_size = 10000;

SET effective_cache_size > 88057, round up to 100000

to ensure the index cost calculation knows the whole index will be
cached, which it clearly could be with 4GB RAM.

If the cost is still wrong, it is because the index order doesn't
correlate physically with the key columns. Use CLUSTER.

Best Regards, Simon Riggs

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