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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2474) CQL support for compound columns
Date Fri, 10 Jun 2011 17:11:59 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13047296#comment-13047296
] 

T Jake Luciani commented on CASSANDRA-2474:
-------------------------------------------

Details of the current CF mapping in hive for static vs dynamic columns is here:

http://www.datastax.com/docs/0.8/brisk/about_hive#mapping-hive-external-tables-to-cassandra-column-families

HBase uses the Hive MAP<k,v> type to do this.

Search in http://wiki.apache.org/hadoop/Hive/HBaseIntegration for
"Hive MAP to HBase Column Family"

bq. Wouldn't it be fairly easy to create a MetaStore that wrapped any other MetaStore and
taught it about the :row syntax?

Sure but this would still require a custom hive build so users of say EMR wouldn't be able
to use it... We might be able to make a stand alone hive metastore service to support the
syntax but it feels like a bad solution...

I don't see what is so bad about mapping each column and subcolumn so its own row like the
Cassandra Hive driver does today.  This is the most natural fit for SQL.

Example: 
   key1 : { col1 : {subcol1:val1, subcol2: val2}}

maps to:

key, column, subcol, value
key1, col1, subcol1, val1
key1, col1, subcol2, val2


 


> CQL support for compound columns
> --------------------------------
>
>                 Key: CASSANDRA-2474
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2474
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: API, Core
>            Reporter: Eric Evans
>              Labels: cql
>             Fix For: 1.0
>
>
> For the most part, this boils down to supporting the specification of compound column
names (the CQL syntax is colon-delimted terms), and then teaching the decoders (drivers) to
create structures from the results.

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