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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-258) Use skip scan when SELECT DISTINCT on leading row key column(s)
Date Wed, 01 Jun 2016 17:34:59 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-258?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15310723#comment-15310723
] 

James Taylor commented on PHOENIX-258:
--------------------------------------

I think what we need is an int[] indexed by the slot position to get the correct padding to
use because the padding necessary depends on the slot position. For example, if we have a
schema like VARCHAR, INT, INT, we need to pad for the 2nd and 3rd slot position. We don't
need to consider the 1st position, because we'll always have an actual key to base our seek
next hint on. For each subsequent slot position, we need to know the continuous fixed length
position *from that point forward*.

> 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
>            Assignee: Lars Hofhansl
>             Fix For: 4.8.0
>
>         Attachments: 258-WIP.txt, 258-v1.txt, 258-v10.txt, 258-v11.txt, 258-v12.txt,
258-v13.txt, 258-v14.txt, 258-v2.txt, 258-v3.txt, 258-v4.txt, 258-v5.txt, 258-v6.txt, 258-v7.txt,
258-v8.txt, 258-v9.txt, 258.txt, DistinctFixedPrefixFilter.java, in-clause.png
>
>
> 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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