Re: cursor empty

[Philipp Kraus <philipp.kraus@xxxxxxxxxxxxxxx>]

Am 08.05.2018 um 16:18 schrieb David G. Johnston <david.g.johnston@xxxxxxxxx>:

On Tue, May 8, 2018 at 6:36 AM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:

select * from vectorize('myvec');
fetch all from myvec;

Can you explain me, which part is wrong?

I am going to say:

perform pivottable( ...

https://www.postgresql.org/docs/10/static/plpgsql-statements.html#PLPGSQL-STATEMENTS-SQL-NORESULT

"Sometimes it is useful to evaluate an _expression_ or SELECT query but discard the result, for example when calling a function that has side-effects but no useful result value. To do this in PL/pgSQL, use the PERFORM statement:

PERFORM query;

This executes query and discards the result.  ..."
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

​It discards the results but not the side-effect, which in this case is creating a named portal in the session.  While the name of the portal, as returned by the function, is indeed lost the portal still exists, with the same name, and since the name is known by the caller anyway the attempt to make use of the portal succeeds (no failure and the column structure is known).  Maybe you are right about the contents of the portal being lost due to the perform but that behavior isn't evident from the the section you quote.

Thanks you both for this hint with the „discard“ :-)

I have modified my pivot-table function so that it returns the cursor directly, see my Gist: https://gist.github.com/flashpixx/66fb3dcd557cc9e93eb22ba692085622

After the pivot-function is run I can fetch all the cursor data.

Phil