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From "Ethan Wang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-153) Implement TABLESAMPLE clause
Date Fri, 09 Jun 2017 18:35:18 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16044823#comment-16044823
] 

Ethan Wang commented on PHOENIX-153:
------------------------------------

Spec of this patch. Feedback plz.

++
++Belows are SUPPORTED
++
===BASE CASE====
select * from Person;
select * from PERSON TABLESAMPLE 0.45;

===WHERE CLAUSE====
select * from PERSON where ADDRESS = 'CA' OR name>'tina3';
select * from PERSON TABLESAMPLE 0.49 where ADDRESS = 'CA' OR name>'tina3';
select * from PERSON TABLESAMPLE 0.49 where ADDRESS = 'CA' OR name>'tina3' LIMIT 1;


===Wired Table===
select * from LOCAL_ADDRESS TABLESAMPLE 0.79;
select * from SYSTEM.STATS TABLESAMPLE 0.41;


===CORNER CASE===
select * from PERSON TABLESAMPLE 0;
select * from PERSON TABLESAMPLE 1.45;
select * from PERSON TABLESAMPLE kko;




++
++belows are NOT SUPPORTED
++
===Subquery and outter join not supporting===
select * from (select * from PERSON where ADDRESS = 'CA') TABLESAMPE 0.2 where Name > 'tina10'

===AGGREGATION===
select count(*) from PERSON TABLESAMPLE 0.5 LIMIT 2

> Implement TABLESAMPLE clause
> ----------------------------
>
>                 Key: PHOENIX-153
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-153
>             Project: Phoenix
>          Issue Type: Task
>            Reporter: James Taylor
>            Assignee: Ethan Wang
>              Labels: enhancement
>
> Support the standard SQL TABLESAMPLE clause by implementing a filter that uses a skip
next hint based on the region boundaries of the table to only return n rows per region.



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