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https://issues.apache.org/jira/browse/IMPALA-7547?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16607703#comment-16607703
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Peter Ebert commented on IMPALA-7547:
-------------------------------------

Agree it sounds similar, perhaps add as a sub-task?

> For distinct queries use dictionary encoded page instead of reading all data
> ----------------------------------------------------------------------------
>
>                 Key: IMPALA-7547
>                 URL: https://issues.apache.org/jira/browse/IMPALA-7547
>             Project: IMPALA
>          Issue Type: Improvement
>            Reporter: Peter Ebert
>            Priority: Major
>
> When dictionary encoding is in use the lookup table should contain a distinct 
> list of all values in the data, can skip reading the values and just read the 
> header to get distinct values.
>  
> Realize this would be a big change to the read/scanner threads but could 
> greatly speed up distinct queries.



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