Re: Crash with a CUBE query on 9.6

Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> The attached test case crashes on REL9_6_STABLE and master. On 9.5, it
> worked.

As best I can tell, this is the fault of commit 804163bc2. The problem
query can be simplified to

SELECT
STDDEV(DISTINCT floor(sale.cn)),
AVG(DISTINCT floor(sale.cn))
FROM sale,vendor
WHERE sale.vn=vendor.vn
GROUP BY CUBE((sale.cn,sale.dt,sale.dt),(sale.pn,sale.prc),(sale.qty,sale.vn)),sale.qty order by 1,2 ;

The two aggregates share a "pertrans" state, but finalize_aggregates
does not account for that and calls process_ordered_aggregate_single()
twice on the same pertrans state. The second time crashes because we
already deleted the tuplesort object the first time.

Probably, the loop in finalize_aggregates needs to be split into two,
one over the pertrans states and then a second one over the peragg states.
But this code has been hacked up enough since I last looked at it that
I'm hesitant to try to fix it myself.

regards, tom lane