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From Tyler Hobbs <>
Subject Re: Question about SizeTieredCompactionStrategy in C* 2.0: not all SSTables are being compacted
Date Tue, 08 Oct 2013 18:49:13 GMT
SizeTieredCompactionStrategy only compacts sstables that are a similar size
(by default, they basically need to be within 50% of each other).  Perhaps
your first SSTable was very large or small compared to the others?

On Mon, Oct 7, 2013 at 8:06 PM, Sameer Farooqui <>wrote:

> Hi,
> I have a fresh 1-node C* 2.0 install with a demo keyspace created with the
> SizeTiered compaction strategy.
> I've noticed that in the beginning this keyspace has just one SSTable:
> demodb-users-jb-1-Data.db
> But as I add more data to the table and do some flushes, the # of SSTables
> builds up. After I have a handful of SSTables, I trigger a flush using
> 'nodetool flush demodb users', but then not ALL of the SSTables get
> compacted.
> I've noticed that the 1st SSTable remains the same and doesn't disappear
> after the compaction, but the latter SSTables do get compacted into one new
> Data file.
> Is there a reason why the first SSTable is special and it is not
> disappearing after compaction?
> Also, I think I noticed that if I wait a few days and run another
> compaction, then that 1st SSTable does not compacted (and it disappears).
> Can someone help explain why the 1st SSTable behaves this way?

Tyler Hobbs
DataStax <>

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