Adar Dembo has posted comments on this change. ( http://gerrit.cloudera.org:8080/10968 )
Change subject: schema: add is_deleted virtual column ...................................................................... Patch Set 6: > > - last-updated-timestamp per-row. If I understand tablet internals > > correctly, this can't ever be provided with per-row granularity, since we > > dispose of per-row timestamps during compaction after the ancient history > > watermark. I think the best we could do here is to provide it per scan > > batch. > > I'm not sure this is correct, but I'm following up with Mike (and looking at > the code) to find out for sure. Mike says that you're right; UNDO GC can and will discard the INSERT UNDO representing the insertion of a row, even if the row is still alive. So once the row's insertion is behind the ancient history mark, there's no guarantee of there being even a single UNDO or REDO record for the row, which means we can't provide a last-updated-timestamp (or created-timestamp, or whatever). -- To view, visit http://gerrit.cloudera.org:8080/10968 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I56eb1d44ba8bfbd76d8bb794b8076b695782939e Gerrit-Change-Number: 10968 Gerrit-PatchSet: 6 Gerrit-Owner: Adar Dembo <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Dan Burkert <[email protected]> Gerrit-Reviewer: Grant Henke <[email protected]> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Mike Percy <[email protected]> Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Comment-Date: Fri, 20 Jul 2018 18:56:25 +0000 Gerrit-HasComments: No
