Hao Hao has posted comments on this change. ( http://gerrit.cloudera.org:8080/8804 )
Change subject: KUDU-1704: add BOUNDED_READ scan mode ...................................................................... Patch Set 1: (2 comments) http://gerrit.cloudera.org:8080/#/c/8804/1/src/kudu/common/common.proto File src/kudu/common/common.proto: http://gerrit.cloudera.org:8080/#/c/8804/1/src/kudu/common/common.proto@228 PS1, Line 228: Boundedly stale reads are not repeatable: two stale reads, even if they : // use the same staleness bound, can execute at different timestamps and thus : // return inconsistent results. However, it allows read-your-writes for each : // client, as the picked timestamp must be higher than the one of the last : // write or read, known from the propagated timestamp. > Hum, if we're waiting for a clean timestamp then the read is repeatable, ri Right, but I think the point is each read the server may pick different timestamps. Even given the same propagated time stamp, the 'clean' timestamp may not be the same at different time. Or maybe I missed something? http://gerrit.cloudera.org:8080/#/c/8804/1/src/kudu/tserver/tablet_service.cc File src/kudu/tserver/tablet_service.cc: http://gerrit.cloudera.org:8080/#/c/8804/1/src/kudu/tserver/tablet_service.cc@2136 PS1, Line 2136: // Do not return the picked snapshot timestamp for BOUNDED_READ mode. > why? I agree with your comment on the Jira "Moreover each server should be free to choose a timestamp such as this, as long as it respects the aforementioned condition, which is why we shouldn't reuse timestamps across servers in this mode and shouldn't return the chosen snapshot timestamp back to the client." So here I did not return the timestamp. :) Does this still sound reasonable? -- To view, visit http://gerrit.cloudera.org:8080/8804 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I84ddb981a1a0f199d4e66f5d5097318f8c785a48 Gerrit-Change-Number: 8804 Gerrit-PatchSet: 1 Gerrit-Owner: Hao Hao <hao....@cloudera.com> Gerrit-Reviewer: David Ribeiro Alves <davidral...@gmail.com> Gerrit-Reviewer: Hao Hao <hao....@cloudera.com> Gerrit-Reviewer: Kudu Jenkins Gerrit-Comment-Date: Tue, 12 Dec 2017 21:43:26 +0000 Gerrit-HasComments: Yes
