What Are Private Data Collections?

(Hyperledger Fabric v2.x) Private data collections specify subsets of organizations that endorse, commit, or query private data on the channel.

Use private data collections in cases where you want a group of organizations on the channel to share data and to prevent the other organizations on the channel from seeing the data. Private data is distributed peer to peer and not by blocks, so the transaction data is kept confidential from the ordering service. Collections help you reduce the number of channels and their required maintenance on your network.

The primary components in a private data collection are:

• The private data that you specify in your private data collection definition. Private data is sent with the gossip protocol from peer to peer within the organizations that you specify in your policy. Private data is stored in a private database on the peer. The ordering service isn't used and can't see the private data.
• A hash of the data, which is endorsed, ordered, and written to each peer on the channel. This hash is evidence of the transaction and can be used for audit purposes.

When you deploy a chaincode, you can associate it with one or more private data collections.