Re: PATCH: decreasing memory needlessly consumed by array_agg

On Tue, 2014-04-01 at 13:08 -0400, Tom Lane wrote:
> I think a patch that stood a chance of getting committed would need to
> detect whether the aggregate was being called in simple or grouped
> contexts, and apply different behaviors in the two cases.

The simple context doesn't seem like a big problem even if we change
things as Tomas suggests:

"IMNSHO these are the issues we really should fix - by lowering the
initial element count (64->4) and using a single memory context."

In the simple context, there's only one context regardless, so the only
cost I see is from reducing the initial allocation from 64 to some lower
number. But if we're doubling each time, it won't take long to get
there; and because it's the simple context, we only need to do it once.

Regards,
Jeff Davis