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From Sameer Farooqui <sam...@blueplastic.com>
Subject Question about SizeTieredCompactionStrategy in C* 2.0: not all SSTables are being compacted
Date Tue, 08 Oct 2013 01:06:45 GMT
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?

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