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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1608) [Hbase Shell] Relational Algrebra Operators
Date Wed, 17 Oct 2007 00:46:57 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12535385
] 

stack commented on HADOOP-1608:
-------------------------------

Comments on version 11 of this patch:

+ In BooleanExpression, you are doing a split using the strings " OR " and " AND ".  Does
this imply OR or AND can never appear at end of a line?  (Or does the parser convert newlines
to spaces?).  Why not make UNION and INTERSECTION final static strings?
+ Comparator has a   @SuppressWarnings("deprecation").  Do you need this?  Same in IdentityFilterMap.
Can you update your code so it uses non-deprecated API?
+ Cloning has one 'n' only so TableClonning should be CloningTable (Maybe better named as
CloneTable?).  In the getConf, you have an if/else.  The else is not needed since you do a
return out of the if block.  Also in TableJoin and Projection (Is Projection a query?  Or
an expression?  Same for Selection.  Should there be a relational operators package rather
than query and expression?  Whats difference between a Command and an Expression?  Why is
Substitute a Command and Projection a query?).

Good stuff Edward.

> [Hbase Shell] Relational Algrebra Operators
> -------------------------------------------
>
>                 Key: HADOOP-1608
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1608
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: contrib/hbase
>    Affects Versions: 0.14.1
>         Environment: All environments 
>            Reporter: Edward Yoon
>            Priority: Minor
>             Fix For: 0.16.0
>
>         Attachments: patch_v01.txt, patch_v02.txt, patch_v03.txt, patch_v04.txt, patch_v05.txt,
patch_v06.txt, patch_v07.txt, patch_v08.txt, patch_v09.txt, patch_v10.txt, patch_v11.txt
>
>
> Development of relational algebra operators has begun.
>  * Projection 
>   ** selects a subset of the columnfamilies of a relation  
>   ** Result = π ~column_list~ (Relation) 
> {code}
> Hbase > Result = Relation.Projection('year','legnth');
> Hbase > save Result into table('result');
> {code}
>  * Selection
>   ** See : HADOOP-2003 issue's description
> {code}
> Hbase > Result = Relation.Selection(length > 100 and studioName = 'Fox'); 
> Hbase > save Result into table('result');
> {code}
>  * Group
>   ** more details about 'GROUP' operation will be handled in HADOOP-1658 issue. 
>  * θ Join
>  ** The join of two relations R1(A ~1~,A ~2~,...,A ~n~) and R2(B~1~,B~2~,...,B~m~) is
a relation with degree k=n+m and attributes (A ~1~,A ~2~,...,A ~n~, B ~1~,B ~2~,...,B ~m~)
that satisfy the join condition
> {code}
> Hbase > R1 = table('movieLog_table');
> Hbase > R2 = table('personInfo_table');
> Hbase > Result = R1.join(R1.producer: = R2.ROW) and R2; or Result = R1.join(R1.actor:hero
= R2.Row) and R2;
> {code}

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