On Tue, Apr 7, 2020 at 5:56 AM Alexander Korotkov <a.korot...@postgrespro.ru> wrote: > > On Tue, Apr 7, 2020 at 12:58 AM Kartyshov Ivan > <i.kartys...@postgrespro.ru> wrote: > > On 2020-04-04 03:14, Alexander Korotkov wrote: > > > I think that now we would be fine with single LSN and single TIMEOUT. > > > In future we may add multiple LSNs/TIMEOUTs or/and support for > > > expressions as LSNs/TIMEOUTs if we figure out it's necessary. > > > > > > I also think it's good to couple waiting for lsn with beginning of > > > transaction is good idea. Separate WAIT FOR LSN statement called in > > > the middle of transaction looks problematic for me. Imagine we have RR > > > isolation and already acquired the snapshot. Then out snapshot can > > > block applying wal records, which we are waiting for. That would be > > > implicit deadlock. It would be nice to evade such deadlocks by > > > design. > > Ok, here is a new version of patch with single LSN and TIMEOUT. > > I think this quite small feature, which already received quite amount > of review. The last version is very pinched. But I think it would be > good to commit some very basic version, which is at least some > progress in the area and could be extended in future. I'm going to > pass trough the code tomorrow and commit this unless I found major > issues or somebody objects. >
I have gone through this thread and skimmed through the patch and I am not sure if we can say that this patch is ready to go. First, I don't think we have a consensus on the syntax being used in the patch (various people didn't agree to LSN specific syntax). They wanted a more generic syntax and I see that we tried to implement it and it turns out to be a bit complex but that doesn't mean we just give up on the idea and take the simplest approach and that too without a broader agreement. Second, on my quick review, it seems there are a few things like error handling, interrupt checking which need more work. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
