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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10355) Failover RPC's from client using region replicas
Date Fri, 14 Feb 2014 02:21:19 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13901036#comment-13901036

Devaraj Das commented on HBASE-10355:

Looks good overall. One question -
Consider a case where a table is created with three replicas. All the replicas are not assigned
(hence, the meta is not updated with the locations yet). Now a client comes in, and the information
that he sees would be partial (let's say location_for_replica_0 and location_for_replica_2
are known). The location for replica_1 would be null. It seems like the client wouldn't know
about the missing location until he refetches the row from the meta (which would not happen
until there is activity like a region move). I am talking about the ReplicaRegionServerCallable
class. Maybe if the location is null, the client should hit the meta always?
When we support online schema changes for #replicas, in the case where we reduce the count,
we would have to cancel the RPCs that are trying to hit the no-longer-existent replica. Similarly,
when we increase the count, we should discover these new replicas.

One nit is that all the methods/fields that you made public for tests should be annotated
with VisibleForTesting.

> Failover RPC's from client using region replicas
> ------------------------------------------------
>                 Key: HBASE-10355
>                 URL: https://issues.apache.org/jira/browse/HBASE-10355
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Client
>            Reporter: Enis Soztutar
>            Assignee: Nicolas Liochon
>             Fix For: 0.99.0
>         Attachments: 10355.v1.patch

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