Re: using limit - Mailing list pgsql-admin

From Michael Holt
Subject Re: using limit
Date
Msg-id f3f619af829b15d8b901614cef0074ac@mail.gmail.com
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In response to using limit  ("Anibal David Acosta" <aa@devshock.com>)
List pgsql-admin

This really depends on the type of query you’re talking about. If there’s only one row in the table you’re querying then no, I don’t think it’ll change anything. If you’re querying a single row using a primary key it shouldn’t change anything. If you’re doing an aggregate query, say a sum of a bunch of rows, it also won’t improve performance.

 

If you’re doing a query on a table with multiple rows and not filtering by a primary key or other unique index then yes, it will improve the query.

 

From: pgsql-admin-owner@postgresql.org [mailto:pgsql-admin-owner@postgresql.org] On Behalf Of Anibal David Acosta
Sent: Thursday, December 16, 2010 11:19 AM
To: pgsql-admin@postgresql.org
Subject: [ADMIN] using limit

 

Hi

I really like to do efficient SQL queries so, my question is if I am expecting no more than one row from a select, using  the LIMIT 1 could improve the performance?

 

If I use my logic, the LIMIT 1 instruction tell to postgres that stop searching when found 1 record, but maybe it is unnecessary

 

 

Thanks

 

Anibal

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