Re: Out of Memory errors are frustrating as heck!

Gunther <raj@gusw.net> writes:
> Now I give you a bt so we have something to look at:

> #0  AllocSetAlloc (context=0x1168230, size=385) at aset.c:715
> #1  0x000000000084e6cd in palloc (size=385) at mcxt.c:938
> #2  0x000000000061019c in ExecHashJoinGetSavedTuple (file=file@entry=0x8bbc528,
hashvalue=hashvalue@entry=0x7fff2e4ca76c,
>      tupleSlot=0x10856b8, hjstate=0x11688e0) at nodeHashjoin.c:1277

I'm pretty sure that's not the droid we're looking for.
ExecHashJoinGetSavedTuple does palloc a new tuple, but it immediately
sticks it into a TupleTableSlot that will be responsible for freeing
it (when the next tuple is stuck into the same slot).  I'd suggest
continuing a few times and looking for other code paths leading
to AllocSetAlloc in this context.

My first thought on noticing the SELECT DISTINCT was that you might be
hitting the grouping-function-related leak that Andres fixed in 9cf37a527;
but that fix did make it into 11.2 (by just a couple of days...).  Still,
maybe there's another issue in the same area.

            regards, tom lane