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https://issues.apache.org/jira/browse/HBASE-4489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13125474#comment-13125474
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Nicolas Spiegelberg commented on HBASE-4489:
--------------------------------------------
1. If you want to save space, you should probably switch to a UINT32 for the
key range instead of the current INT64. This should scale for up to 2 million
regions.
2. We (FB) have this specified for MD5StringSplit elsewhere, but I think an
mandatory requirement if your goal is "better key splitting" is to provide the
hash function that, given a user-specified key, hash it and return what you
need to insert into HBase. Maybe add a generateKey() function to
SplitAlgorithm interface. Worst case is we make it an identity operation.
Talked with StumbleUpon & Salesforce guys last week about making this something
that users can enable and the HBase Client would transparently do for them.
However, step one is giving users the APIs they need to manually do proper key
distribution.
> 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-branch0.90-v2.patch, HBASE-4489-branch0.90-v3.patch,
> HBASE-4489-trunk-v1.patch, HBASE-4489-trunk-v2.patch,
> HBASE-4489-trunk-v3.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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