Yes, a limit should speed up your query from the sounds of things.
*From:* Anibal David Acosta [mailto:a...@devshock.com] *Sent:* Thursday, December 16, 2010 11:34 AM *To:* 'Michael Holt'; pgsql-admin@postgresql.org *Subject:* RE: [ADMIN] using limit Is a table with 10 million of rows with a primary key but conditions used in select are not part of PK. My table is like this: Column 1 – PK Column 2 – Indexed Column 3 – Indexed Column 2 and Column 3 are Indexed in the same index but they are not mark as unique or PK The Query is like this: Select column1 from myTable where Column2 between X and Y I am expecting just one record *De:* Michael Holt [mailto:mich...@aers.ca] *Enviado el:* jueves, 16 de diciembre de 2010 04:23 p.m. *Para:* Anibal David Acosta; pgsql-admin@postgresql.org *Asunto:* RE: [ADMIN] using limit 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-ow...@postgresql.org [mailto: pgsql-admin-ow...@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
