I'd like to get the size (in **bytes**, and # of keys) of an Amazon S3 bucket.  

I'm looking for an **efficient** way to get the size of bucket. 

One possible way(which is **NOT** efficient): I can get the key list of the bucket and sum up the size of each key. This is inefficient when I have thousand of key because I have to look for each key's size. 

Is there any **efficient** solution?? 

***UPDATE:***  

following code is not what I looking for(because it's not efficient): 

```
bucket = conn.get_bucket("bucket_name")
total_size = 0
for key in bucket.list():
   total_size += key.size

```