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From aaron morton <>
Subject Re: Read latency is over 1 minute on a column family with 400,000 rows
Date Mon, 01 Aug 2011 09:40:01 GMT
Having 2056 live SSTables is very odd. Minor compaction should automatically reduce that number.
What settings for min_compaction_threshold and max_compaction_threshold did you use when creating
the CF ? 

You can check them with node tool getcompactionthreshold . The default is min 4 and max 32.

You can also set them using nodetool setcompactionthreshold (Note the value is not persisted
across a restart). 

To provoke a minor compaction run nodetool flush. Minor compactions are preferred to major
as they keep SSTables with the compaction buckets, where as major creates a single large file
which will not be compacted again for a long time.  

Hope that helps.

Aaron Morton
Freelance Cassandra Developer

On 1 Aug 2011, at 17:08, Teijo Holzer wrote:

> Looks like a broken node, just restart Cassandra on that node. Might want to wait for
the compaction to finish on the other nodes.
> Also, don't forget to JMX gc() manually after the compaction has finished to delete the
files on each node.
> On 01/08/11 16:29, myreasoner wrote:
>> On the node that the compaction returned almost immediately:
>> *woot@n50:~$ /opt/cassandra/bin/nodetool -h localhost compactionstats
>> pending tasks: 66*
>> However, messages shown on other nodes are:
>> compaction type: Major
>> keyspace: MyKeyspace
>> column family: Fingerprint
>> bytes compacted: 25505066421
>> bytes total: 45573108438
>> compaction progress: 55.97%
>> -----------------
>> pending tasks: 1
>> --
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