[
https://issues.apache.org/jira/browse/HADOOP-1608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12544733
]
Edward Yoon commented on HADOOP-1608:
-------------------------------------
>> Exceptions are suppressed in maps and configurations. They are just printed
>> on stderr, which is better than nothing, but jobs should fail. Create a
>> Runtime exception from the checked exception so you can throw it where
>> exceptions are not allowed. When you have a ParseException but you're only
>> allowed throw ParseException, and the map task should fail, create an IOE
>> out of the PE and throw that.
OK.
>> The GROUP help says this: "Group rows by value of an attribute and apply
>> aggregate function independently to each group of rows"... but I do not see
>> an 'aggregate function' in the example given. Am I missing something?
More details about 'GROUP' operation will be handled in HADOOP-1658 issue.
If you want, i'll drop it from the hadoop-1608.
But, i'd like to submit some classes for group to svn tree.
>> The SAVE command wants to run a mapreduce job to copy into result table.
>> Should say it runs a MR job in help.
OK.
> [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, patch_v12.txt, patch_v13.txt,
> patch_v14.txt, patch_v15.txt, patch_v16.txt, patch_v17.txt, patch_v18.txt,
> patch_v19.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;
> or Result = R1.join(R1.actor:hero = R2.Row and R1.studioName = 'Fox' and
> R2.occupation = 'singer') and R2;
> {code}
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
