difference between compaction, repair, clean

[Jonathan Colby <jo...@gmail.com>]

I'm a little unclear on the differences between the nodetool operations:

- compaction
- repair 
- clean

I understand that compaction consolidates the SSTables and physically performs deletes by taking into account the Tombstones.  But what does clean and repair do then?

Re: difference between compaction, repair, clean

[Narendra Sharma <na...@gmail.com>]

Short answers:
- compaction - Initiate immediate full compaction. Removes deleted data.
- clean - Initiates immediate cleanup i.e. remove the data that is deleted
and that doesn't belong to this node. Internally performs full compaction.
- repair - Used to make different copies (replicas) of data consistent by
exchanging data with with other replicas.

The details on following links should be good to understand them in detail:
http://www.datastax.com/docs/0.7/utilities/nodetool
<http://www.datastax.com/docs/0.7/utilities/nodetool>
http://wiki.apache.org/cassandra/NodeProbe
<http://wiki.apache.org/cassandra/NodeProbe>
http://wiki.apache.org/cassandra/Operations

<http://wiki.apache.org/cassandra/Operations>Thanks,
Naren

On Wed, Mar 30, 2011 at 12:57 PM, Jonathan Colby
<jo...@gmail.com>wrote:

> I'm a little unclear on the differences between the nodetool operations:
>
> - compaction
> - repair
> - clean
>
> I understand that compaction consolidates the SSTables and physically
> performs deletes by taking into account the Tombstones.  But what does clean
> and repair do then?
>
>
>
>


-- 
Narendra Sharma
Solution Architect
*http://www.persistentsys.com*
*http://narendrasharma.blogspot.com/*