Michaël Figuière created CASSANDRA-8517:
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             Summary: Make client-side Token Aware Balancing possible with 
Global Indexes
                 Key: CASSANDRA-8517
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8517
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Michaël Figuière


This is a follow up ticket for CASSANDRA-6477, to consider enabling client-side 
Token Awareness Balancing with Global Indexes, a it would be a pity to loose 
this efficient optimization when using these new indexes. My original comment 
was:

{quote}
Something that hasn't been mentioned so far in this thread is client side's 
Token Aware Balancing. So far when a query relies on a Secondary Index, it 
doesn't have any partition key specified in its where clause which means that 
the driver will fall back on the underlying balancing policy, which is DC aware 
round robin by default in the DS Java Driver. That's the appropriate behavior 
as there's no node that can be better than another as a coordinator in this 
situation.
With Global Indexes, in order for the Driver to still be able to perform Token 
Aware Balancing, it'll need to be able to figure out which index will be used, 
which doesn't seems to be always trivial in the above examples, especially if 
several columns and/or indexes are involved in the WHERE clause. So here we 
might need to include an extra information about it in the Prepare response 
message of the Native Protocol, if the indexes to be involved can be figured 
out at Prepare-time.
{quote}



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