Re: FreezeLimit underflows in pg14 and 15 causing incorrect behavior in heap_prepare_freeze_tuple

On Sat, Jun 22, 2024 at 10:43 AM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> Hmm. So perhaps this subtraction results in the desired behavior for
> freeze limit -- but by using FreezeLimit as the cutoff_xid for
> heap_prepare_freeze_tuple(), you can still end up considering freezing
> tuples with xmax older than OldestXmin.

Using a FreezeLimit > OldestXmin is just wrong. I don't think that
that even needs to be discussed.

> This results in erroring out with "cannot freeze committed xmax" on 16
> and master but not erroring out like this in 14 and 15 for the same
> tuple and cutoff values.

I don't follow. I thought that 16 and master don't have this
particular problem? Later versions don't use safeLimit as FreezeLimit
like this.

--
Peter Geoghegan