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From "Ben Lau (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14576) New HFile version for optimized reverse scans
Date Wed, 18 May 2016 23:59:13 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15290115#comment-15290115

Ben Lau commented on HBASE-14576:

Hi [~syuanjiang] I'm not currently working on the hfile format revision.  The (to my knowledge)
mostly complete/correct patch I included before in HBASE-14283 is what I have still.  I haven't
had time to work on open source since then.  I may have time this quarter though to come back
to the patch and fix conflicts/address any issues people raise.  Is this ticket blocking anything
for you?

> New HFile version for optimized reverse scans
> ---------------------------------------------
>                 Key: HBASE-14576
>                 URL: https://issues.apache.org/jira/browse/HBASE-14576
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Ben Lau
>            Assignee: Ben Lau
> A new ticket to finish the work from HBASE-14283, which will fix the HFileReader seekBefore()
previous block size calculation bug but make the resulting reverse scan take more I/O than
a forward scan.  
> Fixing the bug in the long term requires an HFile version bump, either major or minor.
 We will put the previous block's size in the HFileBlock header instead of trying to calculate
it directly using block offset arithmetic.  
> Per [~anoop.hbase]'s suggestion, I created this ticket so that we can separate the issue
of fixing the bug (the responsibility of HBASE-14283) and the issue of getting reverse scans
to run quickly (the responsibility of this ticket).  It is also unlikely that this ticket
will be backported to old versions of HBase eg 0.98 whereas HBASE-14283 can be.  

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