Re: Parallel Aggregate costs don't consider combine/serial/deserial funcs

On Mon, Apr 11, 2016 at 12:47:29AM +1200, David Rowley wrote:
> Hi,
>
> I realised a few days ago that the parallel aggregate code does not
> cost for the combine, serialisation and deserialisation functions at
> all.
>
> I've attached a patch which fixes this.
>
> One small point which I was a little unsure of in the attached is,
> should the "if (aggref->aggdirectargs)" part of
> count_agg_clauses_walker() be within the "if
> (!context->combineStates)". I simply couldn't decide. We currently
> have no aggregates which this affects anyway, per; select * from
> pg_aggregate where aggcombinefn <> 0 and aggkind <> 'n'; so for now
> I've left it outwith.
>
> Another thing I thought of is that it's not too nice that I have to
> pass 3 bools to count_agg_clauses() in order to tell it what to do. I
> was tempted to invent some bitmask flags for this, then modify
> create_agg_path() to use the same flags, but I thought I'd better not
> cause too much churn with this patch.

[This is a generic notification.]

The above-described topic is currently a PostgreSQL 9.6 open item. Robert,
since you committed the patch believed to have created it, you own this open
item. If that responsibility lies elsewhere, please let us know whose
responsibility it is to fix this. Since new open items may be discovered at
any time and I want to plan to have them all fixed well in advance of the ship
date, I will appreciate your efforts toward speedy resolution. Please
present, within 72 hours, a plan to fix the defect within seven days of this
message. Thanks.