Index docs question

I setup a cluster with two nodes(2 shards+1 replica) without save the
_source.
Through the ES head, the cluster is green, and I see the docs is about 0.9
billion;
but after some time without doing any thing, the docs becomes to 0.45
billion or so.
More strange, after some time again without doing any thing, the docs
becomes to 0.9 billion again.
Who can help explain how ES calculate the docs numbers??

Anything in the logs?

On Thu, May 24, 2012 at 4:10 AM, jackiedong jackiedong168@gmail.com wrote:

I setup a cluster with two nodes(2 shards+1 replica) without save the
_source.
Through the ES head, the cluster is green, and I see the docs is about 0.9
billion;
but after some time without doing any thing, the docs becomes to 0.45
billion or so.
More strange, after some time again without doing any thing, the docs
becomes to 0.9 billion again.
Who can help explain how ES calculate the docs numbers??