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Posted to issues@hbase.apache.org by "Nicolas Spiegelberg (Commented) (JIRA)" <ji...@apache.org> on 2012/02/15 20:46:59 UTC

[jira] [Commented] (HBASE-5403) Checkpoint the compressed HLog

    [ https://issues.apache.org/jira/browse/HBASE-5403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13208724#comment-13208724 ] 

Nicolas Spiegelberg commented on HBASE-5403:
--------------------------------------------

We had discussed this:  https://issues.apache.org/jira/browse/HBASE-4608?focusedCommentId=13192604

What is the benefit of checkpointing versus just rolling the log?
                
> Checkpoint the compressed HLog
> ------------------------------
>
>                 Key: HBASE-5403
>                 URL: https://issues.apache.org/jira/browse/HBASE-5403
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Liyin Tang
>            Assignee: Liyin Tang
>
> Let's assume that HBase replication can be based on replaying the HLog in the replica cluster.
> The replica process could be crash during the replay. Obviously, the replica process need a way to start from the lastest check point in the HLog, even the HLog is compressed.
> So the proposal is to write a series of checkpoints within the HLog. 
> Each each checkpoint will have a header with some special sequence of bytes.
> And between each checkpoints, HLog should use new dictionaries to compress.

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