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From "Chris Herron (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5025) Schema push/pull race
Date Thu, 06 Dec 2012 20:29:10 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13512078#comment-13512078
] 

Chris Herron commented on CASSANDRA-5025:
-----------------------------------------

[~jbellis]: patch 5025-v2.txt works better. For the same test, after 60s, the CF creation
time drops from sub-second to 5 seconds average. Delayed rectifySchema work will still interfere
with coincident schema migrations, but I think this is the right compromise. Thank you!

Minor: import for {{Callable}} was dropped, but is still referenced at line 229.

[~xedin]: This test was not endorsing a high rate of CF creation for real world use, the goal
was to investigate if/why CF creation time was {{O(N)}}.
                
> Schema push/pull race
> ---------------------
>
>                 Key: CASSANDRA-5025
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5025
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.1.0
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>            Priority: Minor
>             Fix For: 1.1.8
>
>         Attachments: 5025.txt, 5025-v2.txt
>
>
> When a schema change is made, the coordinator pushes the delta to the other nodes in
the cluster.  This is more efficient than sending the entire schema.  But the coordinator
also announces the new schema version, so the other nodes' reception of the new version races
with processing the delta, and usually seeing the new schema wins.  So the other nodes also
issue a pull to the coordinator for the entire schema.
> Thus, schema changes tend to become O(n) in the number of KS and CF present.

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