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From aaron morton <aa...@thelastpickle.com>
Subject Re: Column family has more SSTables than threshold but no minorcompaction is running
Date Tue, 20 Sep 2011 22:05:42 GMT
yes in 0.8 the compaction thresholds are for buckets of files. 

Files are put into buckets where the size of each file is +/- half the size of the average
size. Files smaller than 50MB (from memory) are all put in the first bucket. 

You can change the compaction thresholds via nodetool, and trigger a minor compaction by flushing.
Again via node tool.

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

On 21/09/2011, at 9:34 AM, Konstantin Naryshkin wrote:

> I believe that minor compactions work on tables of same or similar size, so as long as
your tables do not fall within a small range of each other in terms of size, Cassandra does
not see an opportunity to run a minor compaction.
> 
> ----- Original Message -----
> From: "myreasoner" <myreasoner@gmail.com>
> To: cassandra-user@incubator.apache.org
> Sent: Tuesday, September 20, 2011 2:30:26 PM
> Subject: Column family has more SSTables than threshold but no minorcompaction is running
> 
>                Column Family: CF_1
>                SSTable count: 249
>                Space used (live): 15120496328
>                Space used (total): 15120496328
>                Number of Keys (estimate): 18860800
>                Memtable Columns Count: 0
>                Memtable Data Size: 0
>                Memtable Switch Count: 2483
>                Read Count: 442
>                Read Latency: NaN ms.
>                Write Count: 208741548
>                Write Latency: NaN ms.
>                Pending Tasks: 0
>                Key cache capacity: 200000
>                Key cache size: 2395
>                Key cache hit rate: NaN
>                Row cache capacity: 200000
>                Row cache size: 221
>                Row cache hit rate: NaN
>                Compacted row minimum size: 104
>                Compacted row maximum size: 73457
>                Compacted row mean size: 394
> 
> Current compaction thresholds: min = 4,  max = 32
> 
> As shown above, the # of SStables exceeds the max, the node load is light
> but it's not running minor compaction on this Column family.  I don't want
> to run major compaction manually from time to time.  Is there anything I can
> tune?
> 
> --
> View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Column-family-has-more-SSTables-than-threshold-but-no-minorcompaction-is-running-tp6813230p6813230.html
> Sent from the cassandra-user@incubator.apache.org mailing list archive at Nabble.com.


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