in 1.2 bloom filters and compression meta data were moved off heap. in 2.0 index samples were also taken off heap. 

Row cache has been off heap for a while, and the key cache is still on heap. 
Any other components you were interested in ? 

The best reference will be the NEWS.txt file and the blog posts at datastax.


Aaron Morton
New Zealand

Co-Founder & Principal Consultant
Apache Cassandra Consulting

On 2/01/2014, at 7:08 pm, Jason Wee <> wrote:

Solely by the Cassandra version.  Are you asking about a particular component not mentioned above?

Not exactly. From version to version, the component of cassandra may reside on heap or off heap, so is there a way to determine which component in the cassandra version that may reside on heap or off heap?

On Wed, Jan 1, 2014 at 1:25 AM, Tyler Hobbs <> wrote:

On Tue, Dec 31, 2013 at 7:35 AM, Jason Wee <> wrote:

In Cassandra 1.2 and later, the Bloom filter and compression offset map that store this metadata reside off-heap, greatly increasing the capacity per node of data that Cassandra can handle efficiently. In Cassandra 2.0, the partition summary also resides off-heap.

How do we determine if a cassandra component is on heap or offheap? 

Solely by the Cassandra version.  Are you asking about a particular component not mentioned above?

By off-heap, it means that the object is stored *not* in the allocated heap in jvm but in native memory? 

That's correct.

Tyler Hobbs