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From "Dave Latham (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15368) Add relative window support
Date Tue, 01 Mar 2016 21:04:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15174401#comment-15174401

Dave Latham commented on HBASE-15368:

The generalization of windows is nice, but using relative windows like this has a problem.
 Date tiered compaction assigns a HFile to a window based on the max cell timestamp of the
data in that HFile.  Suppose you have a relative window of "last 24 hours" with 4 HFiles in
it (each with 6 hours of data).  If you compact those files together now you have a single
HFile use max timestamp is up to the present, so none of the cells in any of those files is
going to age to the next window or higher tier.  You're going to be much more likely to have
old data hanging around in newer windows.  I don't think a relative window is workable without
a major reconsideration of compaction within a window and even then I wonder if it works any
better than fixed windows in practice.

> Add relative window support
> ---------------------------
>                 Key: HBASE-15368
>                 URL: https://issues.apache.org/jira/browse/HBASE-15368
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Compaction
>            Reporter: Duo Zhang
>            Assignee: Duo Zhang
>         Attachments: HBASE-15368.patch
> To better determine 'hot' data.

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