Re: Handling memory contexts in aggregate function invoking other built-in aggregate functions

On 5/12/2021, at 5:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Calling numeric_avg_accum in the agg_context is unnecessary, and possibly
> counterproductive (it might leak memory in that context, since like all
> other aggregates it assumes it's called in a short-lived context).

OK, thanks for that, I’ll remove the context switch before calling numeric_avg_accum and test more.

> Are you testing in an --enable-cassert build? If not, do that;
> it might make the cause of the crashes more apparent, thanks to
> CLOBBER_FREED_MEMORY and other debug support.

I did build with --enable-cassert, and I did see the state argument pointer passed to numeric_avg_accum
as 0x7f7f7f7f7f, so now I understand why that was thanks to seeing the information about what that means on the Dev FAQ, thanks for that.

So given you didn’t say I shouldn’t be trying to invoke these aggregate functions as I’m trying to, does that mean in theory there isn’t anything inappropriate about doing this as far as you know?

Cheers,
Matt