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From Chris Burroughs <>
Subject Re: Question about local reads with multiple data centers
Date Thu, 06 Feb 2014 13:35:30 GMT
On 01/29/2014 08:07 PM, Donald Smith wrote:
> My question: will the read process try to read first locally from the datacenter DC2
I specified in its connection string?     I presume so.  (I doubt that it uses the client's
IP address to decide which datacenter is closer. And I am unaware of another way to tell it
to read locally.)

 From the rest if this thread it looks like you were asking about how 
the client selected a Cassandra node to act as a coordinator.  Note 
however that if you are using a DC oblivious CL (ONE, QUORUM) then that 
Cassandra coordinator may send requests to the remote data center.

> Also, will read repair happen between datacenters automatically ("read_repair_chance=0.100000")?
 Or does that only happen within a single data center?

Yes read_repair_chance is global.  There is a separate dc_local repair 
chance if you want to make local reap repairs more common.

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