Re: 9.5: Better memory accounting, towards memory-bounded HashAgg

On Fri, 2014-08-08 at 01:16 -0700, Jeff Davis wrote:
> Either way, it's better to be conservative. Attached is a version of the
> patch with opt-in memory usage tracking. Child contexts inherit the
> setting from their parent.

There was a problem with the previous patch: the parent was unlinked
before the delete_context method was called, which meant that the
parent's memory was not being decremented.

Attached is a fix. It would be simpler to just reorder the operations in
MemoryContextDelete, but there is a comment warning against that. So, I
pass the old parent as an argument to the delete_context method.

Regards,
	Jeff Davis