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From "Rock, Paul" <>
Subject Re: Build an index to for join query
Date Thu, 16 Sep 2010 14:11:54 GMT
Alvin - assuming I understand what you're after correctly, why not make a CF Name_Address(name,
address). Modifying the Cassandra methods to do the "join" you describe seems like overkill
to me...


On Sep 15, 2010, at 7:34 PM, Alvin UW wrote:


I am going to build an index to join two CFs.
First, we see this index as a CF/SCF. The difference is I don't materialise it.
Assume we have two tables:
ID_Address(Id, address) ,  Name_ID(name, id)
Then,the index is: Name_Address(name, address)

When the application tries to query on Name_Address, the value of "name" is given by the application.
I want to direct the read operation  to Name_ID to get "Id" value, then go to ID_Address to
get the "address" value by the "Id" value. So far, I consider only the read operation.
By this way, the join query is transparent to the user.

So I think I should find out which methods or classes are in charge of the read operation
in the above operation.
For example, the operation in cassandra CLI "get Keyspace1.Standard2['jsmith']" calls exactly
which methods
in the server side?

I noted CassandraServer is used to listen to clients, and there are some methods such as get(),
Is it the right place I can modify to implement my idea?



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