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https://issues.apache.org/jira/browse/CASSANDRA-1391?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13190100#comment-13190100
]
Brandon Williams commented on CASSANDRA-1391:
---------------------------------------------
I get exceptions while inducing concurrent schema changes:
{noformat}
ERROR 20:58:10,904 Fatal exception in thread Thread[MigrationStage:1,5,main]
java.lang.NullPointerException
at
org.apache.cassandra.config.ColumnDefinition.toMap(ColumnDefinition.java:150)
at org.apache.cassandra.config.CFMetaData.diff(CFMetaData.java:978)
at
org.apache.cassandra.db.migration.MigrationHelper.updateColumnFamily(MigrationHelper.java:285)
at
org.apache.cassandra.db.migration.MigrationHelper.updateColumnFamily(MigrationHelper.java:200)
at
org.apache.cassandra.db.DefsTable.mergeRemoteSchema(DefsTable.java:360)
at
org.apache.cassandra.db.DefinitionsUpdateVerbHandler$1.runMayThrow(DefinitionsUpdateVerbHandler.java:48)
at
org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:30)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
{noformat}
> Allow Concurrent Schema Migrations
> ----------------------------------
>
> Key: CASSANDRA-1391
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1391
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.7.0
> Reporter: Stu Hood
> Assignee: Pavel Yaskevich
> Priority: Critical
> Fix For: 1.1
>
> Attachments: 0001-CASSANDRA-1391-main.patch,
> 0002-CASSANDRA-1391-fixes.patch, 1391-rebased.txt, CASSANDRA-1391.patch
>
>
> CASSANDRA-1292 fixed multiple migrations started from the same node to
> properly queue themselves, but it is still possible for migrations initiated
> on different nodes to conflict and leave the cluster in a bad state. Since
> the system_add/drop/rename methods are accessible directly from the client
> API, they should be completely safe for concurrent use.
> It should be possible to allow for most types of concurrent migrations by
> converting the UUID schema ID into a VersionVectorClock (as provided by
> CASSANDRA-580).
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