Andrew Wong has posted comments on this change. ( http://gerrit.cloudera.org:8080/9923 )
Change subject: WIP KUDU-16 pt 3: add per-scan-token limits ...................................................................... Patch Set 1: > Patch Set 1: > > (1 comment) After some discussion with Thomas from the Impala team, I think the consensus is that this API isn't that useful. Right now, Impala can't really take advantage of this top-level LimitPerToken API because the scan limit isn't known at the time of token building (although there are likely ways around this through updating Impala's source). The ideal API would be one where a limit could be set per grouop of tokens and the tokens would be able to coordinate with each other to satisfy the exact limit. This is difficult to do, so it's probably off the table for now. That said, the limit is definitely known during the re-hydrating call DeserializeIntoScanner(), so Impala should be able to use the API defined in [725c6ce6391b42331e4ab4210ae4117779cba4a2](https://github.com/apache/kudu/commit/725c6ce6391b42331e4ab4210ae4117779cba4a2) in a similar way to that in this patch, i.e. specifying the overall limit per scanner such that l * t rows are returned across all scanners and returning the first l, since this is still a perf win. -- To view, visit http://gerrit.cloudera.org:8080/9923 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I655f07f10a9a99e9766402729361de97e929136a Gerrit-Change-Number: 9923 Gerrit-PatchSet: 1 Gerrit-Owner: Andrew Wong <[email protected]> Gerrit-Reviewer: Andrew Wong <[email protected]> Gerrit-Reviewer: Dan Burkert <[email protected]> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Comment-Date: Mon, 09 Apr 2018 21:43:58 +0000 Gerrit-HasComments: No
