"Mark Woodward" <pgsql@mohawksoft.com> writes:
> I think it is still a bug. While it may manifest itself as a pg crash on
> Linux because of a feature with which you have issue, the fact remains
> that PG is exeeding its working memory limit.
The problem is that *we have no way to know what that limit is* ---
short of exceeding it and being summarily killed. (BTW, the kernel
doesn't know what the limit is either.) There is simply not any way
to operate robustly under the OOM-kill regime.
While I'll certainly acknowledge that it'd be nice if hashagg had
spill-to-disk capability, that wouldn't alter the fundamental fact that
if you want reliable behavior you MUST turn off OOM kill. There is not
anything we can do at the database level to work around that kernel-level
misdesign.
regards, tom lane