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Re: Difference in query plan when using = or > in where clause
- From: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
- To: Radhika S <radhika(dot)sambamurti(at)gmail(dot)com>
- Cc: pgsql-performance(at)postgresql(dot)org
- Subject: Re: Difference in query plan when using = or > in where clause
- Date: Thu, 27 Sep 2007 13:39:07 +0100
Radhika S wrote: > I am curious as to why this occurs. Why does an = change the query plan so > drastically? > > When my query is: > Select count(*) from View_A WHERE tradedate = '20070801'; > The query plan is as below: > ... > But when my query is: > Select count(*) from View_A WHERE tradedate BETWEEN '20070801' and > '20070901'; > The query plan is: > ... In short, the planner estimates that "tradedate BETWEEN '20070801' and '20070901'" matches more rows than "tradatedate = '20070801'" -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
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