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From VĂ­ctor Hugo Oliveira Molinar <vhmoli...@gmail.com>
Subject Truncate behaviour
Date Tue, 19 Mar 2013 18:50:35 GMT
Hello guys!
I'm researching the behaviour for truncate operations at cassandra.

Reading the oficial wiki page(http://wiki.apache.org/cassandra/API) we can
understand it as:
*"Removes all the rows from the given column family."*

And reading the DataStax page(
http://www.datastax.com/docs/1.0/references/cql/TRUNCATE) we can understand
it as:
*"A TRUNCATE statement results in the immediate, irreversible removal of
all data in the named column family."*

But I think there is a missing and important point about truncate
operations.
At least at 1.2.0 version, whenever I run a truncate operation, C*
automatically creates a snapshot file of the column family, resulting in a
fake free disk space.

I'm intentionally mentioning 'fake free disk space' because I only figured
it out when the machine disk space was at high usage.


- Is it a security C* behaviour of creating snapshots for each CF before
truncate operation?
- In my scenario I need to purge my column family data every day.
  I thought that truncate could handle it based at the docs. But it doesnt.
  And since I dont want to manually delete those snapshots, I'd like to
know if there is a safe and practical way to perform a daily purge of this
CF data.


Thanks in advance!

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