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https://issues.apache.org/jira/browse/CASSANDRA-2231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13008321#comment-13008321
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Ed Anuff edited comment on CASSANDRA-2231 at 3/18/11 5:27 AM:
--------------------------------------------------------------

-From the email conversation around this earlier today, I'm wondering if a bit 
in the trailing byte at the end of each component could be used for a sort 
order flag?-

I'd like to suggest we put a byte just before the length/value part that if 
it's non-zero, reverses the comparer results.  Both component parts must have 
the same sort order byte (i.e. both are 0 or both are 1) or a RuntimeException 
is thrown.

For context, we're looking at doing something in the JPA implementation via 
annotations that's functionally similar to how App Engine defines indexes in 
it's index.yaml - 
http://code.google.com/appengine/docs/java/configyaml/indexconfig.html



      was (Author: edanuff):
    From the email conversation around this earlier today, I'm wondering if a 
bit in the trailing byte at the end of each component could be used for a sort 
order flag?

For context, we're looking at doing something in the JPA implementation via 
annotations that's functionally similar to how App Engine defines indexes in 
it's index.yaml - 
http://code.google.com/appengine/docs/java/configyaml/indexconfig.html


  
> Add CompositeType comparer to the comparers provided in 
> org.apache.cassandra.db.marshal
> ---------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-2231
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2231
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Contrib
>    Affects Versions: 0.7.3
>            Reporter: Ed Anuff
>            Priority: Minor
>         Attachments: 0001-Add-compositeType-and-DynamicCompositeType.patch, 
> 0001-Add-compositeType.patch, edanuff-CassandraCompositeType-1e253c4.zip
>
>
> CompositeType is a custom comparer that makes it possible to create 
> comparable composite values out of the basic types that Cassandra currently 
> supports, such as Long, UUID, etc.  This is very useful in both the creation 
> of custom inverted indexes using columns in a skinny row, where each column 
> name is a composite value, and also when using Cassandra's built-in secondary 
> index support, where it can be used to encode the values in the columns that 
> Cassandra indexes.  One scenario for the usage of these is documented here: 
> http://www.anuff.com/2010/07/secondary-indexes-in-cassandra.html.  Source for 
> contribution is attached and has been previously maintained on github here: 
> https://github.com/edanuff/CassandraCompositeType

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