[jira] Updated: (HBASE-1730) Near-instantaneous online schema and table state updates

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

     [ https://issues.apache.org/jira/browse/HBASE-1730?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack updated HBASE-1730:
-------------------------

    Attachment: 1730-v2.patch

More work on HCD.  Removes UnmodifyableHCD.  Since HCD now implements map, can just do a Collections.unmodifyableMap wrapper on delegate Map.  Jackson is sweet in that for new HCD.toString, I ask jackson to serialize to a StringReader.  It produces something like a ruby Map -- e..g. {"NAME": "cf1", "IN_MEMORY": true, "COMPRESSION", "LZO"} -- only I can then take this 'String' and deserialize to get me back the original HCD.  Nice for shell, UI, and content of a znode (I don't think we need to get toBinaryString in there since I don't think we have binary data in schema and table state).  Working on HTD next.

> Near-instantaneous online schema and table state updates
> --------------------------------------------------------
>
>                 Key: HBASE-1730
>                 URL: https://issues.apache.org/jira/browse/HBASE-1730
>             Project: Hadoop HBase
>          Issue Type: Improvement
>            Reporter: Andrew Purtell
>            Assignee: stack
>             Fix For: 0.21.0
>
>         Attachments: 1730-v2.patch, 1730.patch
>
>
> We should not need to take a table offline to update HCD or HTD. 
> One option for that is putting HTDs and HCDs up into ZK, with mirror on disk catalog tables to be used only for cold init scenarios, as discussed on IRC. In this scheme, regionservers hosting regions of a table would watch permanent nodes in ZK associated with that table for schema updates and take appropriate actions out of the watcher. In effect, schema updates become another item in the ToDo list.
> {{/hbase/tables/<table-name>/schema}}
> Must be associated with a write locking scheme also handled with ZK primitives to avoid situations where one concurrent update clobbers another. 

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