Reads from multiple buckets?

How does Couchbase handle reads from different buckets i.e. suppose I have a table in RDBMS which is quite big and does not fit in a bucket. So i make multiple buckets in couchbase. Now when I have to read the entire table how does couchbase know where the data is and how does it reads the data properly?

Also, I stored each documentID as table`s name+ Prikey of the table

eg: table - employee , pkey -id

couchbase doc id -> emp 1

So now if it is in multiple buckets in multiple nodes … How does couchbase read it i.e. collect the data and return it … like how you`ll write the view and how internally it works?

Also from my understanding each Bucket has Vbuckets right … So while quering for a key do we have to give the bucket name and then couchbase finds the suitable vbucket … What if a table is distributed amongst various buckets … How would it work then?

The vBuckets(bucket) really are limited by your server size. Couchbase writes all your data to Hard Disk and just puts the Most Recently Used Items into memory.

Sounds like you are moving from RDBMS to Key=>Value(Documents).
Its best if you read over document Design.
http://www.couchbase.com/docs/couchbase-devguide-2.1.0/relating-documents-for-retrieval.html
It will give you insight into how to put documents into couchbase

Tool to Move your RDBMS to Couchbase
http://blog.couchbase.com/mysql-couchbase-using-talend-etl