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https://issues.apache.org/jira/browse/PHOENIX-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16044823#comment-16044823
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Ethan Wang edited comment on PHOENIX-153 at 6/14/17 5:51 PM:
-------------------------------------------------------------
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;
===AGGREGATION===
select count( * ) from PERSON TABLESAMPLE 0.5 LIMIT 2
select count( * ) from (select NAME from PERSON limit 20)
===SUB QUERY===
select * from (select /*+NO_INDEX*/ * from PERSON tablesample 0.1 where Name >
'tina10') where ADDRESS = 'CA'
===QUERY being OPTMIZED===
select * from PERSON tablesample 0.8 (goes to IDX_ADDRESS_PERSON index table,
table sample carry on)
++
++belows are NOT SUPPORTED
++
===outter join not supporting===
select * from PERSON1, PERSON2 tablesample 0.7 where PERSON1.Name = PERSON2.NAME
was (Author: aertoria):
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;
===AGGREGATION===
select count(*) from PERSON TABLESAMPLE 0.5 LIMIT 2
select count(*) from (select NAME from PERSON limit 20)
===SUB QUERY===
select * from (select /*+NO_INDEX*/ * from PERSON tablesample 0.1 where Name >
'tina10') where ADDRESS = 'CA'
===QUERY being OPTMIZED===
select * from PERSON tablesample 0.8 (goes to IDX_ADDRESS_PERSON index table,
table sample carry on)
++
++belows are NOT SUPPORTED
++
===outter join not supporting===
select * from PERSON1, PERSON2 tablesample 0.7 where PERSON1.Name = PERSON2.NAME
> 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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