From: | "Nico Callewaert" <callewaert(dot)nico(at)telenet(dot)be> |
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To: | <pgsql-novice(at)postgresql(dot)org> |
Subject: | JOIN vs. LEFT JOIN |
Date: | 2009-01-28 10:43:24 |
Message-ID: | DD54522572014D84A247B4662D5620AD@etsinformatics.local |
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Lists: | pgsql-novice |
Hi !
I heard that it is always better to use a full JOIN rather than a LEFT JOIN, for performance reasons. Is that correct ?
But it's barely possible to use full JOINS all the time, since most of the lookup fields are not required.
Example : in the customer table, the customer type is a looup field to a customer_type table. But that is not required to post the record. So I was thinking to create a record in the customer_type table with ID = -1. And in case the customer type is NULL, to assign it the value -1. That way, it will be always possible to do a full JOIN. I was wondering if that is good practice or rather nonsense ?
Many thanks in advance,
Nico
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