what is read set and write set in Hyperledger Fabric 1.0?

Question

I am confused to understand what is read and write set in fabric 1.0, Kindly someone explain by taking example if possible.

Answer 1

Read set and write sets are related to a transaction.

Suppose you have a transaction, read key a1 (suppose a1's value = value_a1, version = version_a1), and key a2(suppose a2's value = value_a2, version = version_a2), suppose we want a1's value to be decremented, and a2's value incremented;

So this transaction's read set is :

{a1, value_a1, version_a1; a2, value_a2, version_a2}; 

i.e., the related key, its value, its version list;

This transaction's write set is:

{a1, (value_a1 -1); a2, (value_a2 +1)}; 

i.e., the updated key and its new value list.

Read set and write set are used for transaction endorsement and commit (update world state) at committer.