PostgreSQL Performance - Re: planner with index scan cost way off actual cost,

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Re: planner with index scan cost way off actual cost,

Simon Riggs

2006-03-21, 8:33 pm

On Fri, 2006-03-17 at 11:09 +0100, Guillaume Cottenceau wrote:

> INFO: index " idx_sent_msgs_date_t
heme_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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