[jira] [Commented] (HBASE-6985) Serve timeranged reads during log split

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

    [ https://issues.apache.org/jira/browse/HBASE-6985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617641#comment-13617641 ] 

Nicolas Liochon commented on HBASE-6985:
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If we want to do this while keeping consistency, an option it to add set a configurable time barrier, to make impossible to send a put with an older timestamp than this barrier. This would be either a fixed one updated by the client, or a mobile one (ex: 15 minutes ago). This barrier could only be incremented. 

So:
 - on a put, the region server would check than the put does not contain a timestamp older than the barrier.
 
 This would allow:  
  - coupled with HBASE-5930 (Periodically flush the Memstore), to do reads directly on the HFiles without compromising consistency;
  - during recovery (or if recovery is slowed down because some blocks are corrupted) to continue to read, once the region is allocated again.
  
As a consequence, we would be able to continue to write and to read when there is a crash.

This is in the same area as HBASE-2357, but simpler as we address only a subset of reads (the timeranged ones).
                
> Serve timeranged reads during log split
> ---------------------------------------
>
>                 Key: HBASE-6985
>                 URL: https://issues.apache.org/jira/browse/HBASE-6985
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: Gregory Chanan
>            Priority: Minor
>
> For tracking serving timeranged reads portion of HBASE-6752.

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