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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Trivial Update of "Hbase/HowToMigrate" by stack
Date Wed, 15 Jul 2009 23:55:19 GMT
Dear Wiki user,

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The following page has been changed by stack:
http://wiki.apache.org/hadoop/Hbase/HowToMigrate

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  You cannot migrate unless all has been major compacted first.  Major compaction is necessary
because the way deletes work changed in 0.20 hbase.
  
- -ROOT- and .META. flush frequently so could mess up your nice and tidy single-file per store
major_compacted hbase layout.  They won't flush if there have not been edits.  So, make sure
your cluster is not taking writes and hasn't been doing so for a good while before starting
up the major compaction process.
+ -ROOT- and .META. flush frequently so could mess up your nice and tidy single-file per store
major_compacted hbase layout.  They won't flush if there have not been edits.  So, make sure
your cluster is not taking writes and hasn't been doing so for a good while before starting
up the major compaction process.  Getting your cluster to shutdown with one file only in -ROOT-
and .META. may be a bit tough so to help, facility has been added to the HEAD of the 0.19
branch that will allow you major compact catalog regions in a shutdown hbase.  This facility
only works on the -ROOT- and .META. catalog tables, not on user space tables.  For usage,
type:
  
- TODO: Command-line tool to major compact an offline cluster.
+ {{{./bin/hbase org.apache.hadoop.hbase.regionserver.HRegion}}}
  
  ==== Migrating ====
  

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