Re: Parallelized polymorphic aggs, and aggtype vs aggoutputtype

David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> I've attached my proposed patch for the user defined aggregate docs.

I whacked this around some more and pushed it.

While working on that, I noticed what seems to me to be a minor bug.
The behavior that I'd expect (and that I documented) for a deserialization
function is that it just allocates its result in the current, short-lived
memory context, since it will be the combine function's responsibility to
merge that into the long-lived transition state. But it looks to me like
the deserialization functions in numeric.c are allocating their results
in the aggregate context, which will mean a leak. (For example,
numeric_avg_deserialize creates its result using makeNumericAggState
which forces the result into the agg context.)

Now this leak isn't going to be real significant unless we accumulate a
whole lot of partial results in one query, which would be unusual and
maybe even impossible in the current parallel-query environment. But it
still seems wrong. Please check, and submit a patch if I'm right about
what's happening.

regards, tom lane