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https://issues.apache.org/jira/browse/CASSANDRA-4866?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis resolved CASSANDRA-4866.
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Resolution: Duplicate
bq. Have I misunderstood how the concurrent schema updates work, or is
simultaneous CF creation not supported?
The latter. Should be fixed in 1.2. (CASSANDRA-3794)
> ConfigurationException when creating column families simultaneously
> -------------------------------------------------------------------
>
> Key: CASSANDRA-4866
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4866
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.1.2
> Reporter: Richard Low
>
> This reproduces the problem:
> Suppose there are just two nodes A and B.
> * Create two client threads with separate connections.
> * Connect them to A and they both create the same column family foo.
> * One gets ID 1000, the other ID 1001.
> * On the mutation stage, A processes the two CF creations, and asynchronously
> sends the creation messages to B.
> * Suppose B gets 1001 first, it creates it.
> * A creates 1000
> * B tries to create 1000 and fails (which is OK, we only want one CF)
> * A tries to create 1001 and fails (which is OK, we only want one CF)
> * Errors in the log like 'ConfigurationException: Column family ID mismatch
> (found 1001; expected 1000)'
> * Inserts, hints and repair now fails because the IDs are not consistent
> across the cluster. Inserts fail with
> 'org.apache.cassandra.db.UnknownColumnFamilyException: Couldn't find
> cfId=1001'
> There's a few problems here:
> One is that DefsTable.mergeSchema applies the change, then calls
> mergeColumnFamilies which could throw ConfigurationException. If
> ConfigurationException is thrown, the local schema is in an invalid state.
> The fix for this is to merge before updating the schema system CF.
> The other issue is that there are two unique identifiers for the CF - the
> name and the ID. It would be better to have just one to avoid this. And I
> think the only safe way of doing this is to use the CF name, since the IDs
> could be assigned in different orders.
> Have I misunderstood how the concurrent schema updates work, or is
> simultaneous CF creation not supported?
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