[jira] [Updated] (CASSANDRA-1391) Allow Concurrent Schema Migrations

["Pavel Yaskevich (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-1391?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Pavel Yaskevich updated CASSANDRA-1391:
---------------------------------------

    Attachment: 0002-avro-removal.patch
                0001-new-migration-schema-and-avro-methods-cleanup.patch

New migration model uses internal 'system'.'keyspace' CF as backing storage from the state of the schema. Internal structure of the 'keyspaces' CF was described in the Jonathan's comment. Decisions about attribute updates are made according to timestamps of the columns in new that CF.

Avro dependency is completely removed, all {to/from}Avro methods cleaned. Please make sure that you apply both patches.

Rebased with the latest trunk (last commit 3ed1e0789f10de8e9638bec20bed2e59fa35b0d0)
                
> 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
>             Fix For: 1.1
>
>         Attachments: 0001-new-migration-schema-and-avro-methods-cleanup.patch, 0002-avro-removal.patch, 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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