David Ribeiro Alves has posted comments on this change. ( http://gerrit.cloudera.org:8080/10503 )
Change subject: IMPALA-6812: Fix flaky Kudu scan tests ...................................................................... Patch Set 1: When you say playing around, you on a private branch? Unless you actually added read-your-writes to impala in another patch/branch somewhere, I think what you are referring to as "read your writes" is the "old (2017) implementation, that gave the choice of either READ_LATEST or READ_AT_SNAPSHOT. Note that the latter is _not_ read your writes (nowhere in Kudu was this ever called "read your writes"), it's actually read at snapshot, despite what the impala commit messages at the time say, and even though no-one is actually setting a timestamp it still does choose one on its own. It seems that the READ_AT_SNAPSHOT implementation is buggy. In order of this to work properly the _frontent_ must choose a timestamp before it's passed to the scanners on the backend. Even when this is done the AHW in Kudu needs to be far enough behind to let all the scanners start, it was at some point shortened to something like 5 minutes, which is likely not enough. In order to get true "read-your-writes" impala needs to use the proper mode in the kudu side (READ_YOUR_WRITES) which was added just recently. This mode should not complain about AHW or care about snapshot timestamps. -- To view, visit http://gerrit.cloudera.org:8080/10503 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I70df84f2cbc663107f2ad029565d3c15bdfbd47c Gerrit-Change-Number: 10503 Gerrit-PatchSet: 1 Gerrit-Owner: Thomas Marshall <[email protected]> Gerrit-Reviewer: Dan Hecht <[email protected]> Gerrit-Reviewer: David Ribeiro Alves <[email protected]> Gerrit-Reviewer: Thomas Marshall <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Comment-Date: Tue, 12 Jun 2018 22:43:38 +0000 Gerrit-HasComments: No
