> On Thu, Nov 1, 2018 at 7:09 AM Michael Paquier <mich...@paquier.xyz> wrote: > > On Tue, Oct 23, 2018 at 10:43:38AM +0900, Michael Paquier wrote: > > Well, following the same kind of thoughts, txid_current_snapshot() uses > > sort_snapshot() to remove all the duplicates after fetching its data > > from GetSnapshotData(), so wouldn't we want to do something about > > removal of duplicates if dummy PGXACT entries are found while scanning > > the ProcArray also in this case? What I would think we should do is not > > only to patch GetRunningTransactionData() but also GetSnapshotData() so > > as we don't have duplicates also in this case, and do things in such a > > way that both code paths use the same logic, and that we don't need to > > have sort_snapshot() anymore. That would be more costly though... > > My apologies it took a bit longer than I thought. I got a patch on my > desk for a couple of days, and finally took the time to finish something > which would address the concerns raised here. As long as we don't reach > more than hundreds of thousands of entries, there is not going to be any > performance impact. So what I do in the attached is to revert 1df21ddb, > and then have GetRunningTransactionData() sort the XIDs in the snapshot > and remove duplicates only if at least one dummy proc entry is found > while scanning, for xids and subxids. This way, there is no need to > impact most of the instance deployments with the extra sort/removal > phase as most don't use two-phase transactions. The sorting done at > recovery when initializing the standby snapshot still needs to happen of > course. > > The patch is added to the upcoming CF for review.
Unfortunately, patch has some conflict with the current master. Could you please post a rebased version?
