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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: memtable flush thresholds
Date Mon, 12 Sep 2011 14:16:12 GMT
see memtable_total_space_in_mb at
http://thelastpickle.com/2011/05/04/How-are-Memtables-measured/

On Mon, Sep 12, 2011 at 6:55 AM, Sorin Julean <sorin.julean@gmail.com> wrote:
> Hi,
>
>  I've checked the memtable flush (cassandra 0.8.4)  and it seams to me it
> hapens sooner then the threshold is reached.
>
> Here's the threshould's (the default ones calculated for a heap size of
> -Xmx1980M):
>     ColumnFamily: idx_graphable (Super)
>       Key Validation Class: org.apache.cassandra.db.marshal.BytesType
>       Default column value validator:
> org.apache.cassandra.db.marshal.BytesType
>       Columns sorted by:
> org.apache.cassandra.db.marshal.UTF8Type/org.apache.cassandra.db.marshal.UTF8Type
>       Row cache size / save period in seconds: 0.0/0
>       Key cache size / save period in seconds: 200000.0/14400
>       Memtable thresholds: 0.5671875/1440/121 (millions of ops/minutes/MB)
>       GC grace seconds: 864000
>       Compaction min/max thresholds: 4/32
>       Read repair chance: 1.0
>       Replicate on write: true
>
> In the logs it seams to me none oh the thresold is reached ( definitively
> minutes threshold is not reached ).
>
> 9-08 20:12:30,136 MeteredFlusher.java (line 62) flushing high-traffic column
> family ColumnFamilyStore(table='graph', columnFamily='idx_graphable')
>  INFO [NonPeriodicTasks:1] 2011-09-08 20:12:30,144 ColumnFamilyStore.java
> (line 1036) Enqueuing flush of
> Memtable-idx_graphable@915643571(4671498/96780112 serialized/live bytes,
> 59891 ops)
>  INFO [FlushWriter:111] 2011-09-08 20:12:30,145 Memtable.java (line 237)
> Writing Memtable-idx_graphable@915643571(4671498/96780112 serialized/live
> bytes, 59891 ops)
>  INFO [FlushWriter:111] 2011-09-08 20:12:30,348 Memtable.java (line 254)
> Completed flushing [...]/cassandra/data/graph/idx_graphable-g-23-Data.db
> (4673905 bytes)
>
>
> Could someone clarify it for me ?
> "high-traffic column family" has a special meaning ?
>
> Many thanks,
> Sorin
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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