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From Jonathan Ellis <>
Subject Re: memtable_threshold
Date Mon, 28 Mar 2011 22:15:37 GMT
It's closer to 8x than 2x for small values. Java objects simply use a
lot more memory than you'd think, and it takes multiple objects to
store a column.

On Mon, Mar 28, 2011 at 4:15 PM, ruslan usifov <> wrote:
> 2011/3/29 Narendra Sharma <>
>> This is because the memtable threshold is not correct to the last byte.
>> The threshold basically account for column name, value and timestamp (or the
>> serialized column). It doesn't account for all the in-memory overhead for
>> maintaining the data and references etc.
> Overhead in 2 times???? Hm why so many. Also in JMX (throw jconsole) i don't
> see any overhead, when memtable reach it memory threshold it will be reset
> to very low value (about 300 - 400 KB)

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support

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