nkeywal created HBASE-5877:
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             Summary: When a query fails because the region has moved, let the 
regionserver returns the new address to the client
                 Key: HBASE-5877
                 URL: https://issues.apache.org/jira/browse/HBASE-5877
             Project: HBase
          Issue Type: Improvement
          Components: client, master, regionserver
    Affects Versions: 0.96.0
            Reporter: nkeywal
            Assignee: nkeywal
            Priority: Minor


This is mainly useful when we do a rolling restart. This will decrease the load 
on the master and the network load.

Note that a region is not immediately opened after a close. So:
- it seems preferable to wait before retrying on the other server. An 
optimisation would be to have an heuristic depending on when the region was 
closed.
- during a rolling restart, the server moves the regions then stops. So we may 
have failures when the server is stopped, and this patch won't help.


The implementation in the first patch does:
- on the region move, there is an added parameter on the regionserver#close to 
say where we are sending the region
- the regionserver keeps a list of what was moved. Each entry is kept 100 
seconds.
- the regionserver sends a specific exception when it receives a query on a 
moved region. This exception contains the new address.
- the client analyses the exeptions and update its cache accordingly...






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