[jira] [Comment Edited] (CASSANDRA-13441) Schema version changes for each upgraded node in a rolling upgrade, causing migration storms

["Jeff Jirsa (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-13441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15972044#comment-15972044 ] 

Jeff Jirsa edited comment on CASSANDRA-13441 at 4/18/17 5:17 AM:
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Aleksey mentioned he had some concerns with the approach in IRC and, more importantly, suggested a cleaner way to do it (rather than change the hashing, write new system tables with fixed time stamps). 

Using this method, we're able to actually push this to 3.0, 3.11, and trunk without causing the ping-pong effect the original patch caused, and it's much cleaner (doesn't go all the way down into the storage engine). 

New patches here:

|| Branch || Testall || Dtest ||
| [3.0|https://github.com/jeffjirsa/cassandra/commits/cassandra-3.0-13441] | [testall|https://circleci.com/gh/jeffjirsa/cassandra/tree/cassandra-3.0-13441] | [dtesthttps://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-devbranch-dtest/16/|] |
| [3.11|https://github.com/jeffjirsa/cassandra/commits/cassandra-3.11-13441] | [testall|https://circleci.com/gh/jeffjirsa/cassandra/tree/cassandra-3.11-13441] | [dtest|https://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-devbranch-dtest/17/] |
| [trunk|https://github.com/jeffjirsa/cassandra/commits/cassandra-13441] | [testall|https://circleci.com/gh/jeffjirsa/cassandra/tree/cassandra-13441] | [dtest|https://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-devbranch-dtest/18/] |


(Unit and dtests are queued now but will likely take some time to complete)


was (Author: jjirsa):
Aleksey mentioned he had some concerns with the approach in IRC and, more importantly, suggested a cleaner way to do it (rather than change the hashing, write new system tables with fixed time stamps). I've pulled the branch for now because it's going to change (significantly)

> Schema version changes for each upgraded node in a rolling upgrade, causing migration storms
> --------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-13441
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13441
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Schema
>            Reporter: Jeff Jirsa
>            Assignee: Jeff Jirsa
>             Fix For: 4.x
>
>
> In versions < 3.0, during a rolling upgrade (say 2.0 -> 2.1), the first node to upgrade to 2.1 would add the new tables, setting the new 2.1 version ID, and subsequently upgraded hosts would settle on that version.
> When a 3.0 node upgrades and writes its own new-in-3.0 system tables, it'll write the same tables that exist in the schema with brand new timestamps. As written, this will cause all nodes in the cluster to change schema (to the version with the newest timestamp). On a sufficiently large cluster with a non-trivial schema, this could cause (literally) millions of migration tasks to needlessly bounce across the cluster.



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