[HBASE-4489] Better key splitting in RegionSplitter

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.90.4
• Fix Version/s: 0.94.0

Release Note

The split algorithm used by RegionSplitter is now a required parameter. Previously there was one split algorithm called MD5StringSplit, which was the default. MD5StringSplit has been renamed to HexStringSplit, and tweaked so that its maximum key is now "FFFFFFFF" instead of "7FFFFFFF. A new split algorithm UniformSplit has been added which treats keys as arbitrary bytes.

• Assignee: Dave Revell
• Reporter: Dave Revell
• Created: 26/Sep/11 21:59
• Updated: 12/Oct/12 05:34
• Resolved: 20/Oct/11 00:10

Description

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.

Issue Links

• is related to: HBASE-4627 Ability to specify a custom start/end to RegionSplitter
• is related to: HBASE-4628 Enhance Table Create Presplit Functionality within the HBase Shell