[jira] [Commented] (HBASE-17931) Assign system tables to servers with highest version

["Phil Yang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-17931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16042489#comment-16042489 ] 

Phil Yang commented on HBASE-17931:
-----------------------------------

2.0.0-alpha will be released soon so back to this issue. AssignmentManager is gone so I'm going to prepare a new patch.

> Assign system tables to servers with highest version
> ----------------------------------------------------
>
>                 Key: HBASE-17931
>                 URL: https://issues.apache.org/jira/browse/HBASE-17931
>             Project: HBase
>          Issue Type: Bug
>          Components: scan
>            Reporter: Phil Yang
>            Assignee: Phil Yang
>            Priority: Blocker
>             Fix For: 2.0.0, 1.4.0
>
>         Attachments: HBASE-17931.v01.patch, HBASE-17931.v02.patch, HBASE-17931.v03.patch
>
>
> In branch-1 and master we have some improvement and new features on scanning which is not compatible.
> A client of old version to a server of new version is compatible (must be a bug if not, maybe need some test?). 
> A client of new version may not be able to read from a server of old version correctly (because of scan limit, moreResults flag, etc), which is ok for major/minor upgrade and we can tell users to upgrade server before upgrading client. But RS also use scan to read meta. If meta table is in RS of old version, all RSs of new version may have trouble while scanning meta table.
> So we should make sure meta table always in servers of new version. Force meta table in Master and upgrade Master first, or assign meta table in region servers with latest version?



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