Re: Bugs in TOAST handling, OID assignment and redo recovery

Hi Heikki,

On Tue, Apr 10, 2018 at 7:07 PM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:

It would seem more straightforward to add a snapshot parameter to GetNewOidWithIndex(), so that the this one caller could pass SnapshotToast, while others pass SnapshotDirty. With your patch, you check the index twice: first with SnapshotDirty, in GetNewOidWithIndex(), and then with SnapshotToast, in the caller.

Hmm. I actually wrote my first patch exactly like that. I am trying to remember why I discarded that approach. Was that to do with the fact that  SnapshotToast can't see all toast tuples either? Yeah, I think so. For example, it won't see tuples with uncommitted-xmin, leading to different issues. Now it's unlikely that we will have a OID conflict where the old tuple has uncommitted-xmin, but not sure if we can completely rule that out.