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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-258) Use skip scan when SELECT DISTINCT on leading row key column(s)
Date Thu, 14 Apr 2016 19:34:25 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-258?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15241775#comment-15241775
] 

Lars Hofhansl commented on PHOENIX-258:
---------------------------------------

If this means nobody else will be looking at it, it's probably not a good idea. I have so
little engineering time these days.

Have been playing around with the SkipScanFilter, but that's not working. We need a filter,
perhaps similar to it that can move on after it has seen the requested distinct prefix if
the key once, the SkipScanFilter is a "match" filter, while a key matches a range it will
include it.

> Use skip scan when SELECT DISTINCT on leading row key column(s)
> ---------------------------------------------------------------
>
>                 Key: PHOENIX-258
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-258
>             Project: Phoenix
>          Issue Type: Task
>            Reporter: ryang-sfdc
>              Labels: gsoc2016
>             Fix For: 4.8.0
>
>
> create table(a varchar(32) not null, date date not null constraint pk primary key(a,date))
> [["PLAN"],["CLIENT PARALLEL 94-WAY FULL SCAN OVER foo"],["    SERVER AGGREGATE INTO ORDERED
DISTINCT ROWS BY [a]"],["CLIENT MERGE SORT"]]             
> We should skip scan.



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