Re: Remove HeapTuple and Buffer dependency for predicate locking functions

On Tue, Jun 25, 2019 at 6:02 AM Andres Freund <andres@anarazel.de> wrote:
> > - CheckForSerializableConflictOut() no more takes HeapTuple nor
> >   buffer, instead just takes xid. Push heap specific parts from
> >   CheckForSerializableConflictOut() into its own function
> >   HeapCheckForSerializableConflictOut() which calls
> >   CheckForSerializableConflictOut(). The alternative option could be
> >   CheckForSerializableConflictOut() take callback function and
> >   callback arguments, which gets called if required after performing
> >   prechecks. Though currently I fell AM having its own wrapper to
> >   perform AM specific task and then calling
> >   CheckForSerializableConflictOut() is fine.
>
> I think it's right to move the xid handling out of
> CheckForSerializableConflictOut(). But I think we also ought to move the
> subtransaction handling out of the function - e.g. zheap doesn't
> want/need that.

Thoughts on this Ashwin?

I think the only part its doing for sub-transaction is SubTransGetTopmostTransaction(xid). If xid passed to this function is already top most transaction which is case for zheap and zedstore, then there is no downside to keeping that code here in common place.