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https://issues.apache.org/jira/browse/HBASE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13271630#comment-13271630
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ramkrishna.s.vasudevan commented on HBASE-5877:
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Just saw the intent behind this JIRA. It is very important and a good feature.
You have done a lot in this but the JIRA says it is Minor :).
bq.It doesn't know if the region is opened yet. We could have this by adding
the info in zk, but it would increase the zk load...
Now how does the updateCachelocation help here. If for some reason the opening
of the region is not yet done and if the client gets RegionMovedException the
client will try to contact the RS thinking the region got moved to it.
Thanks N.
> When a query fails because the region has moved, let the regionserver return
> 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
> Fix For: 0.96.0
>
> Attachments: 5877-v16.txt, 5877-v17.txt, 5877-v17.txt, 5877.v1.patch,
> 5877.v12.patch, 5877.v15.patch, 5877.v18.patch, 5877.v18.patch, 5877.v6.patch
>
>
> 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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