There can be many record with differenet id_ in one collection.
  A collection, as I understand it is a container to hold records
  of a similar form together. It's a bit like  table in a rdms.
Yes this is what i am doing Creating collection for each handle. But the problem is script ~/bin/handle_cache which perform this task get terminated in between without giving any error. May be I was thinking there is a limit to the number of collection in database.
Ok Let me do some more research for solving this problem. And If i am not able to solve it i will let you know.....
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Rishabh Sharma
Software Developer
Anantya R&D
http://www.anantyarnd.in