Re: Startup process on a hot standby crashes with an error "invalid memory alloc request size 1073741824" while replaying "Standby/LOCK" records

On Tue, Oct 04, 2022 at 07:53:11PM -0400, Tom Lane wrote:
> I wrote:
>> PFA a quick-hack fix that solves this issue by making per-transaction
>> subsidiary hash tables. That's overkill perhaps; I'm a little worried
>> about whether this slows down normal cases more than it's worth.
>> But we ought to do something about this, because aside from the
>> duplication aspect the current storage of these lists seems mighty
>> space-inefficient.
>
> After further thought, maybe it'd be better to do it as attached,
> with one long-lived hash table for all the locks. This is a shade
> less space-efficient than the current code once you account for
> dynahash overhead, but the per-transaction overhead should be lower
> than the previous patch since we only need to create/destroy a hash
> table entry not a whole hash table.

This feels like a natural way to solve this problem. I saw several cases
of the issue that was fixed with 6301c3a, so I'm inclined to believe this
usage pattern is actually somewhat common.

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com