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Posted to issues@kudu.apache.org by "Grant Henke (Jira)" <ji...@apache.org> on 2020/06/24 22:15:00 UTC
[jira] [Commented] (KUDU-1291) Efficiently support predicates on
non-prefix key components
[ https://issues.apache.org/jira/browse/KUDU-1291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17144441#comment-17144441 ]
Grant Henke commented on KUDU-1291:
-----------------------------------
A patch was posted for this here: [https://gerrit.cloudera.org/#/c/10983/]
Along with a blog post about the design and in-progress work: [https://kudu.apache.org/2018/09/26/index-skip-scan-optimization-in-kudu.html]
> Efficiently support predicates on non-prefix key components
> -----------------------------------------------------------
>
> Key: KUDU-1291
> URL: https://issues.apache.org/jira/browse/KUDU-1291
> Project: Kudu
> Issue Type: Sub-task
> Components: perf, tablet
> Reporter: Todd Lipcon
> Priority: Major
> Labels: roadmap-candidate
>
> In a lot of workloads, users have a compound primary key where the first component (or few components) is low cardinality. For example, a time series workload may have (year, month, day, entity_id, timestamp) as a primary key. A metrics or log storage workload might have (hostname, timestamp).
> It's common to want to do cross-user or cross-date analytics like 'WHERE timestamp BETWEEN <a> and <b>' without specifying any predicate for the first column(s) of the PK. Currently, we do not execute this efficiently, but rather scan the whole table evaluating the predicate.
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