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Re: Acceptable level of over-estimation?
- From: Gregory Stark <stark(at)enterprisedb(dot)com>
- To: "Carlo Stonebanks" <stonec(dot)register(at)sympatico(dot)ca>
- Cc: <pgsql-performance(at)postgresql(dot)org>
- Subject: Re: Acceptable level of over-estimation?
- Date: Mon, 24 Sep 2007 21:18:25 +0100
"Carlo Stonebanks" <stonec(dot)register(at)sympatico(dot)ca> writes: > Is there a rule of thumb about when the planner's row estimates are too high? > In particular, when should I be concerned that planner's estimated number of > rows estimated for a nested loop is off? By a factor of 10? 100? 1000? Not really. It's a big enough difference for the planner to make a bad decision or it isn't. But if you pressed me I would say a factor of 10 is bad. A factor of 2 is inevitable in some cases. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com
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- Acceptable level of over-estimation?
- From: Carlo Stonebanks
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