Re: Unpredicatable behavior of volatile functions used in cursors - Mailing list pgsql-general

Aleksander Kmetec <aleksander.kmetec@intera.si> writes:
> We're using the following technique for counting the number of rows in a cursor:
> DECLARE instance_cur_1 SCROLL CURSOR FOR
> SELECT util.row_number(), *
> FROM (
>     $LONG_RUNNING_QUERY
> ) ss
> FETCH LAST IN instance_cur_1;

> util.row_number() is a volatile function written in C which simply returns "++internal_counter" every time it is
called.

This isn't gonna work very well if your query involves sorting, because
the SELECT-list is evaluated before the sort step ...

            regards, tom lane