Re: tuplestore API problem

Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> So I tried pass EState.es_tupleTables to tuplestore_begin_heap() to
> trace those TupleTableSlots. Note that if you pass NULL the behavior
> is as before so nothing's broken. Regression passes but I'm not quite
> sure EState.es_tupleTable is only place that holds TupleTableSlots
> passed to tuplestore...

I've got zero confidence in that, and it seems pretty horrid from a
system structural point of view even if it worked: neither tuplestore.c
nor its direct callers have any business knowing where all the slots
are. What might be a bit saner is to remember the slot last passed to
tuplestore_gettupleslot for each read pointer. The implication would be
that we'd be assuming only one slot is used to fetch from any one read
pointer, but that is probably a reasonable restriction.

> I know you propose should_copy boolean parameter would be added to
> tuplestore_gettupleslot().

I already did it, and concluded that not only were all the
tuplestore_gettupleslot calls in nodeWindowAgg broken, but so was
nodeCtescan. I'm open to reverting that patch if you have a better
solution though.

regards, tom lane