JOIN vs. LEFT JOIN
| От | Nico Callewaert |
|---|---|
| Тема | JOIN vs. LEFT JOIN |
| Дата | |
| Msg-id | DD54522572014D84A247B4662D5620AD@etsinformatics.local обсуждение исходный текст |
| Ответы |
Re: JOIN vs. LEFT JOIN
|
| Список | 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
В списке pgsql-novice по дате отправления: