EXPLAIN VERBOSE with parallel Aggregate

There's 2 problems:

1)

I recently noticed that EXPLAIN VERBOSE is a bit bogus when it comes
to parallel aggregates with FILTER (WHERE ...) clauses.

We get;

Output: pg_catalog.sum((sum(num) FILTER (WHERE (num > 0)))) FILTER
(WHERE (num > 0))

Which is simply a lie, we only filter on the partial aggregate, not the combine.

The attached patch just nullifies the combine aggregate's aggfilter
clause during setrefs. We cannot nullify it any sooner, as the
aggfilter is required so that we find the correct partial Aggref in
search_indexed_tlist_for_partial_aggref().

With the attached we get;

Output: pg_catalog.sum((sum(num) FILTER (WHERE (num > 0))))

The patch is very simple.

2)

I'm unsure if the schema prefix on the combine aggregate is a problem
or not. The code path which generates it is rather unfortunate and is
down to func_get_detail() returning FUNCDETAIL_NOTFOUND in
generate_function_name() due to not being able to find a function
named "sum" with the transtype as its only argument. I had thought
that maybe we should add a pg_proc entry for the aggregate with the
transtype, if not already covered by the entry for aggfnoid.
Aggregates where the transtype is the same as the input type work just
fine;

Output: max((max(num)))

The problem with that is adding the pg_proc entry still won't get rid
of the schema as the "p_funcid == funcid" test in
generate_function_name() will fail causing the schema qualification to
occur again. But at least func_get_detail() would be successful in
finding the function.

Any one have any thoughts on if this is a problem?

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services