Re: set the cost of an aggregate function

On Mon, Nov 30, 2009 at 11:53 AM, Jaime Casanova
<jcasanov(at)systemguards(dot)com(dot)ec> wrote:
> 2009/11/30 Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>:
>> Hi,
>>
>> why we can't do $subject? it could have any benefit on the planner?
>>
>
> seems like while we can set the cost of the state transition function,
> that cost is not propagated...

I thought for sure you must be wrong about this, but I just read the
source code and, sure enough, the cost of the transition and final
functions are totally ignored. In fact, there's a comment about this
in cost_agg():

* Note: ideally we should use the pg_proc.procost costs of each
* aggregate's component functions, but for now that seems like an
* excessive amount of work.

...Robert