LIMIT Optimization

From: "alexandre paes :: aldeia digital" <alepaes(at)aldeiadigital(dot)com(dot)br>
To: <pgsql-sql(at)postgresql(dot)org>
Subject: LIMIT Optimization
Date: 2002-01-25 15:59:11
Message-ID: 004601c1a5b9$3b344a60$fc01a8c0@aldeiadigital.com.br
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Hi,

DB2, Sql Server and Oracle have a smart optimization sql-clause (DB2
example):

SELECT * FROM <table> WHERE <cond> ORDER BY <order> OPTMIZATION FOR n ROWS

The [OPTMIZATION FOR] clause turns the query fast by optimize the first "n"
rows.
If the query returns more than "n" rows, the query is slowest if compared
with a normal
query, but it does not have the limitation of PostgreSQL's LIMIT clause.

I think that clause performs the search twice: one for optimize and other if
the # of rows
is great then "n".

It's possible to include this in future releases of PostgreSQL ????

Thanks all! // ...do not attemp to my harmless english... :)

Alexandre Arruda Paes

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