On Wed, Jul 20, 2016 at 7:57 AM, Andres Freund <and...@anarazel.de> wrote:
> On July 19, 2016 7:14:42 PM PDT, Amit Kapila <amit.kapil...@gmail.com> wrote:
>>On Wed, Jul 20, 2016 at 5:02 AM, Andres Freund <and...@anarazel.de>
>>> On 2016-07-19 18:09:59 -0500, Kevin Grittner wrote:
>>>> As far as I can see, to do this the way that Andres and Amit
>>>> suggest involves tying in to indexam.c and other code in incredibly
>>>> ugly ways.
>>> Could you explain the problem you're seing?
>>> Isn't pretty much all all that we need to do:
>>> 1) add a InitSnapshotToast(Snapshot originMVCCSnap), which sets
>>> to the the origin snapshot's lsn
>>> 2) adapt TestForOldSnapshot() to accept both HeapTupleSatisfiesMVCC
>>I also think so. However, it is not clear what is the best place to
>>initialize toast snapshot. One idea could be to do it in
>>GetSnapshotData() after capturing the required information for the
>>valid value of old_snapshot_threshold. Do you have something else in
> There's very few callsites using toast snapshots. I'd just do it there. Don't
> think we ever use GetSnapshotData for them.
I think Snapshot's members whenTaken and lsn are updated/initialized
only in GetSnapshotData(). So if GetSnapshotData() is not used, how
will you expect those fields to be updated. We need those fields to
be updated for TestForOldSnapshot().
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