Re: aggregate function ?

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От Richard Broersma Jr
Тема Re: aggregate function ?
Дата
Msg-id 304157.50040.qm@web31814.mail.mud.yahoo.com
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Ответ на Re: aggregate function ?  (Raimon Fernandez <coder@montx.com>)
Ответы Re: aggregate function ?  (Raimon Fernandez <coder@montx.com>)
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--- Raimon Fernandez <coder@montx.com> wrote:

>
> yes, what I want really is the Sum(b.value_d) - sum(b.value_h)
> accumulate
>
> will be faster a function for this that this SELECT ... ?

Using a custom function could be comparable to a pure SQL statement in performance. However,
sometimes function like this can hide details of the query from the PostgreSQL optimizer.  If this
happens you will see poor query performance.

>
> GlobalGest=# SELECT A.oid, A.concepte, A.deure, A.haver
                         --Your are missing a comma here ^

>             (sum( B.deure )-sum(B.haver)) AS value_sum
>        FROM assentaments AS A
> INNER JOIN assentaments AS B
>          ON A.oid <= B.oid
>    WHERE A.numero=11189
>    GROUP BY A.oid, A.concepte, A.deure, A.haver
>    ORDER BY A.oid;
> ERROR:  schema "a" does not exist

What version of PostgreSQL are you using?

Your version of the query will need to look like this:

    SELECT A1.oid, A1.concepte, A1.deure, A1.haver,
           (sum( A2.deure )-sum(A3.haver)) AS value_sum
      FROM Assentaments AS A1
INNER JOIN Assentaments AS A2
        ON A1.oid <= A2.oid
INNER JOIN Assentaments AS A3
        ON A1.oid <= A3.oid
     WHERE A1.numero=11189
  GROUP BY A1.oid, A1.concepte, A1.deure, A1.haver
  ORDER BY A1.oid;

Regards,
Richard Broersma Jr.

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