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Date: Fri, 01 Nov 2013 20:47:56 +0100
From: Jiri Horky <horky@avast.com>
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Subject: Recompacting all sstables
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Hi all

since we upgraded half of our Cassandra cluster to 2.0.0 and we use LCS,
we hit CASSANDRA-6284 bug. So basically all data in sstables created
after the upgrade are wrongly (non-uniformly within compaction levels)
distributed. This causes a huge overhead when compacting new sstables
(see the bug for the details).

After applying the patch, the distribution of the data within a level is
supposed to recover itself over time but we would like to not to wait a
month or so until it gets better.

So the question. What is the best way to recompact all the sstables so
the data in one sstables within a level would contain more or less the
right portion of the data, in other worlds, keys would be uniformly
distributed across sstables within a level? (e.g.: assumming total token
range for a node 1..10000, and given that L2 should contain 100
sstables, , all sstables within L2 should cover a range of ~100 tokens).

Based on documentation, I can only think of switching to SizeTiered
compaction, doing major compaction and then switching back to LCS.

Thanks in advance
Jiri Horky