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https://issues.apache.org/jira/browse/KYLIN-3490?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16585780#comment-16585780
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ASF subversion and git services commented on KYLIN-3490:
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Commit c9d7f5ec2ff8834f0f1b24610485bb819741206f in kylin's branch
refs/heads/master from Zhong
[ https://gitbox.apache.org/repos/asf?p=kylin.git;h=c9d7f5e ]
KYLIN-3490 introduce DictionaryEnumerator to answer single encoded column
related queries which will not hit cuboid
> For some single column related queries, don't need to query cuboids, only
> dictionaries are enough
> -------------------------------------------------------------------------------------------------
>
> Key: KYLIN-3490
> URL: https://issues.apache.org/jira/browse/KYLIN-3490
> Project: Kylin
> Issue Type: Improvement
> Reporter: Zhong Yanghong
> Assignee: Zhong Yanghong
> Priority: Major
> Fix For: v2.5.0
>
> Attachments: APACHE-KYLIN-3490.patch
>
>
> A common use case for BI tools is as follows:
> # Firstly, extract all of the values of a dimension column
> # Then, select part of the values as filter condition.
> Previously query for the first step requires to hit all of the segments'
> cuboid data, which may not be efficient, especially when the segments occupy
> many regions.
> To use dictionary rather than cuboid data to answer this kind of queries,
> will reduce the cost of many rpcs to hbase.
> Sample queries are as follows:
> {code}
> select A
> from T
> group by A
> {code}
> {code}
> select distinct A
> from T
> {code}
> {code}
> select max(A)
> from T
> {code}
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