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https://issues.apache.org/jira/browse/HBASE-2235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12835985#action_12835985
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Kannan Muthukkaruppan commented on HBASE-2235:
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@stack: You wrote <<<The report of split is not atomic; we are sending 3
separate puts. We don't have means of making a cross-row transaction out of
this operation>>>.
Would keeping all region info for a table as columns under a single row key in
.META. be such a crazy idea? With that you can do atomic mutations to a given
table's region info. The cons would be that entire "rowkey" would be hosted on
a single server... but for most tables that'd probably already be the case
unless it has an exorbitant number of regions.
> Mechanism that would not have -ROOT- and .META. on same server caused failed
> assign of .META.
> ---------------------------------------------------------------------------------------------
>
> Key: HBASE-2235
> URL: https://issues.apache.org/jira/browse/HBASE-2235
> Project: Hadoop HBase
> Issue Type: Bug
> Reporter: stack
> Fix For: 0.20.4, 0.21.0
>
>
> Here is the short story:
> Scenario is a cluster of 3 servers. Server 1. crashed. It was carrying the
> .META. We split the logs. .META. is put on the head of the assignment
> queue. Server 2. happens to be in a state where it wants to report a split.
> The master fails the report because there is no .META. (It fails it ugly with
> a NPE). Server 3. checks in and falls into the assignment code
> (RegionManager#regionsAwaitingAssignment). In here we have this bit of code
> around line #412:
> {code}
> if (reassigningMetas && isMetaOrRoot && !isSingleServer) {
> return regionsToAssign; // dont assign anything to this server.
> }
> {code}
> Because we think this not a single server cluster -- we think there are two
> 'live' nodes -- we won't assign meta.
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