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From "Dave Revell (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4489) Better key splitting in RegionSplitter
Date Wed, 28 Sep 2011 17:59:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13116639#comment-13116639
] 

Dave Revell commented on HBASE-4489:
------------------------------------

@Jonathan Hsieh, thanks for your thoughts.

When you say you agree with jgray: he actually wants to do two things. (1) stop using ASCII
and (2) remove the 0x7F range bug. It sounds like you only agree with removing the 0x7F range
bug but not with avoiding ASCII, for the default split algorithm? 

I agree in principle with your comment about preserving behavior between minor releases. If
there were a valid use case for the existing code, I would agree that we should leave it.
But given its current brokenness, we should fix it all the way instead of creating an intermediate
slightly-broken state that falls short of a real fix. We're already breaking any existing
use cases by virtue of fixing the range bug. We should not create another generation of broken
use cases before making the real fix, IMO.

I agree that tests would be a good idea. I'll hopefully find some time for that soon.
                
> Better key splitting in RegionSplitter
> --------------------------------------
>
>                 Key: HBASE-4489
>                 URL: https://issues.apache.org/jira/browse/HBASE-4489
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.90.4
>            Reporter: Dave Revell
>            Assignee: Dave Revell
>         Attachments: HBASE-4489-branch0.90-v1.patch, HBASE-4489-trunk-v1.patch
>
>
> The RegionSplitter utility allows users to create a pre-split table from the command
line or do a rolling split on an existing table. It supports pluggable split algorithms that
implement the SplitAlgorithm interface. The only/default SplitAlgorithm is one that assumes
keys fall in the range from ASCII string "00000000" to ASCII string "7FFFFFFF". This is not
a sane default, and seems useless to most users. Users are likely to be surprised by the fact
that all the region splits occur in in the byte range of ASCII characters.
> A better default split algorithm would be one that evenly divides the space of all bytes,
which is what this patch does. Making a table with five regions would split at \x33\x33...,
\x66\x66...., \x99\x99..., \xCC\xCC..., and \xFF\xFF.

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