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https://issues.apache.org/jira/browse/HBASE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13271651#comment-13271651
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nkeywal commented on HBASE-5877:
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bq. 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.
Yes, exactly. That's why I kept the sleep in the client code even for this
RegionMoved. We could optimize this by adding a timestamps, with an heuristic
like: "we give two seconds for the region to move after it's closed on the
origin server". Sharing the region state in ZK would be a simpler option, as we
would know if the region has moved or not.
> 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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