Re: functions returning sets

Tom Lane wrote:
> Hmm, this looks like a bug having to do with not resetting state
> correctly for the next invocation of the SRF.  Hard to tell whether
> the bug is in your code or the system's support for SRFs though.

Looks like a bug in ExecScanSubPlan() around line 401:
8<-----------------------------------------------------
if (subLinkType == ANY_SUBLINK)
{
     /* combine across rows per OR semantics */
     if (rownull)
     *isNull = true;
     else if (DatumGetBool(rowresult))
     {
         result = BoolGetDatum(true);
         *isNull = false;
         break;    /* needn't look at any more rows */
     }
}
8<-----------------------------------------------------

If the function returns a set, that comment is wrong, isn't it? I
removed the "break" to run out all the available tuples and got the
correct result:

regression=# select id from foo where 'a' in (select
pgxml_xpath(doc,'/top/node'));
  id
----
  1
  2
  3
(3 rows)

Any guidance on the preferred fix? I don't see an obvious way to
determine if the plan includes a set returning function in
ExecScanSubPlan(), and it seems unfortunate to remove the optimization
for all other cases, especially since targetlist SRFs are deprecated.

Joe