Re: I probably don't understand aggregates. - Mailing list pgsql-novice

From David G Johnston
Subject Re: I probably don't understand aggregates.
Date
Msg-id 1402519308856-5806885.post@n5.nabble.com
Whole thread Raw
In response to I probably don't understand aggregates.  (Markus Neumann <markus.neumann@math.uzh.ch>)
List pgsql-novice
Markus Neumann wrote
> I'm new to postgres, sql and mailing lists, so I think I'm in the right
> place here.
>
> I have a pl/pgsql function, that calls a selfwritten aggregate function
> (consisting of stepfunction and finalfunction) and afterwards processes
> the results.
>
> The Problem:
>
> if I call
>    SELECT myAggrFunction(x) FROM table;
> I get the correct and expected output.
>
> but when myAggrFunction gets called inside the "wrapper"-function, the
> finalfunction gets executed before all rows are processed and hence I
> get a "Division by zero" error.
>
> E.g.
>    SELECT myWrapperFunction(x) FROM table;
>    ERROR: division by zero
>
>
> myWrapperFunction would look something like:
>
>    BEGIN
>      M := myAggrFunction(x);
>      --do some more stuff
>      RETURN M;
>    END;
>
> I hope the description is somehow understandable.
>
> Any feedback will be highly appreciated.
>
> Markus

Is there a reason you cannot provide a self-contained example?

David J.




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