Blockchains provide a number of useful features that a traditional SQL database fails to provide. These include immutable data, consensus & data replication.
In this example a authenticated blockchain is implemented by using a number of features of PostgreSQL & extending PostgreSQL to allow for Peer To Peer (P2P) communication & block consensus.
This also acts as a good example of how to use P2P & a consensus mechanism for reliable data distribution over faulty networks.
By implementing the useful features of a blockchain inside PostgreSQL most of the capabilities of a blockchain are brought into the relational world.