On Tue, Nov 15, 2022 at 3:32 AM Andres Freund <andres@anarazel.de> wrote:
> Furthermore, it is > possible that successor[x] = successor[x'] since the page might be corrupted > and we haven't checked otherwise. > > predecessor[y] = x means that successor[x] = y but in addition we've > checked that y is sane, and that x.xmax=y.xmin. If there are multiple > tuples for which these conditions hold, we've issued complaints about > all but one and entered the last into the predecessor array.
As shown by the isolationtester test I just posted, this doesn't quite work right now. Probably fixable.
I don't think we can follow non-HOT ctid chains if they're older than the xmin horizon, including all cases of xmin being frozen. There's just nothing guaranteeing that the tuples are actually "related".
I understand the problem with frozen tuples but don't understand the concern with non-HOT chains,
could you please help with some explanation around it?
