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Subject: Re: Read latency is over 1 minute on a column family with 400,000
 rows
From: aaron morton <aaron@thelastpickle.com>
In-Reply-To: <4E3634EA.4050709@wetafx.co.nz>
Date: Mon, 1 Aug 2011 21:40:01 +1200
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Message-Id: <D1192FD9-B057-4174-A95E-20715DD48AF6@thelastpickle.com>
References: <1312165382278-6639649.post@n2.nabble.com>
 <4E361554.30608@wetafx.co.nz> <1312169479782-6639774.post@n2.nabble.com>
 <4E361EEF.5080000@wetafx.co.nz> <1312170451093-6639790.post@n2.nabble.com>
 <4E3623B5.1060703@wetafx.co.nz> <1312172987691-6639836.post@n2.nabble.com>
 <4E3634EA.4050709@wetafx.co.nz>
To: user@cassandra.apache.org

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 ?=20

You can check them with node tool getcompactionthreshold . The default =
is min 4 and max 32.=20

You can also set them using nodetool setcompactionthreshold (Note the =
value is not persisted across a restart).=20

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. =20

Hope that helps.

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

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.
>=20
> Also, don't forget to JMX gc() manually after the compaction has =
finished to delete the files on each node.
>=20
> On 01/08/11 16:29, myreasoner wrote:
>> On the node that the compaction returned almost immediately:
>>=20
>> *woot@n50:~$ /opt/cassandra/bin/nodetool -h localhost compactionstats
>> pending tasks: 66*
>>=20
>> 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
>>=20
>>=20
>>=20
>> --
>> View this message in context: =
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Read-late=
ncy-is-over-1-minute-on-a-column-family-with-400-000-rows-tp6639649p663983=
6.html
>> Sent from the cassandra-user@incubator.apache.org mailing list =
archive at Nabble.com.
>=20