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