[ https://issues.apache.org/jira/browse/KYLIN-3490?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Shaofeng SHI updated KYLIN-3490: -------------------------------- Summary: For single column queries, only dictionaries are enough (was: For some single column related queries, don't need to query cuboids, only dictionaries are enough) > For single column queries, 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} -- This message was sent by Atlassian JIRA (v7.6.3#76005)