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From David Leimbach <>
Subject System keyspace leak?
Date Wed, 04 Apr 2012 01:00:36 GMT
I've been trying to understand the overhead of create/drop keyspace on
Cassandra 1.0.8.  It's not free, especially when I've managed to drive up
the LiveDiskSpaceUsed for the Migrations CF in the "system" keyspace up to
over 12 MB of disk.

I've tried doing "nodetool -h localhost repair system" and other nodetool
commands to try to compact the SSTables involved with it, but it never
wants to let go of that slowly growing space.

The Cassandra node in question is in a ring of size 1.

Other than clobbering my data directory, how do I get my space back?  Is it
natural for this to grow seemingly infinitely (even though it's pretty
small increments), or did I find a bug?

The reason I ask is I need to run unit tests in a shared developer
infrastructure with Cassandra, and we were having a little trouble with
TRUNCATE on column families, but that might have been environmental (I've
not looked deeply into it).

Which is less expensive?  Create/Drop, or Truncate?  I don't expect
Truncate to swell the Migration Column Family because it tracks (seemingly)
schema changes.


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