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The "NodeTool" page has been changed by JanneJalkanen: http://wiki.apache.org/cassandra/NodeTool?action=diff&rev1=20&rev2=21 Comment: note about upgradesstables == Scrub == Cassandra v0.7.1 and v0.7.2 shipped with a bug that caused incorrect row-level bloom filters to be generated when compacting sstables generated with earlier versions. This would manifest in IOExceptions during column name-based queries. v0.7.3 provides "nodetool scrub" to rebuild sstables with correct bloom filters, with no data lost. (If your cluster was never on 0.7.0 or earlier, you don't have to worry about this.) Note that nodetool scrub will snapshot your data files before rebuilding, just in case. + == upgradesstables == + + While "scrub" does rebuild your sstables, it will also discard data it deems broken and create a snapshot, which you have to remove manually. If you just wish to rebuild your sstables without all that jazz, then use "nodetool upgradesstables". This is useful e.g. when you are upgrading your server, or changing compression options. + + upgradesstables is available from Cassandra 1.0.4 onwards. + == Cfhistograms == Excellent description from: http://narendrasharma.blogspot.com/2011/04/cassandra-07x-understanding-output-of.html
