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Re: Important speed difference between a query and a

From: Frederic Jolliton <fred-pg(at)jolliton(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Important speed difference between a query and a
Date: 2003-04-24 15:47:53
Message-ID: 86el3rsxqu.fsf@mau.localdomain (view raw or flat)
Thread:
Lists: pgsql-performance
> (PostgreSQL 7.3.2 on i386-portbld-freebsd4.7, compiled by GCC 2.95.4)
>
> I've a curious performance problem with a function returning set of
> rows.  The query alone is very fast, but not when called from the
> function.
>
> To "emulate" a parametred view, I created a function as follow:
>
> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info
>     AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10'
>     LANGUAGE sql;

Setting enable_seqscan to off give same result speed between the query
and the function !

So, the query in the function is not using index but the exact same
query alone does !

Is there an explanation ?

-- 
Frédéric Jolliton


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