Best database type to store data that will be used with a blockchain

Question

For a project, I'm using Hyperledger Composer Fabric to create a blockchain for an integrated healthcare system for integrity and fast access purposes. I don't want to store the actual healthcare records on the blockchain because they'll be large. Instead, I was thinking of storing a hash of the record on the blockchain and storing the records in a database. What kind of database would be best? I've used relational databases and SQL before only. Could this suit? I've seen some people say to store the location of the data on the blockchain too, how would you do this? This is only a small project, so I'm looking for simple solutions rather than some I see which are for real, enterprise systems.

Answer 1

Storing just the hash on the blockchain is fine. Just use the Composer Rest Server functionality to expose a RESTful endpoint to add and read the data. You can call this endpoint from the data layer of your application.

In terms of the database, If you know SQL use a SQL database. The kind depends on the development environment you are using. I am a Microsoft fan but MSSQL Server costs much more than POSTGres or MySQL. If the database is not big, look at the AWS RDS cloud databases.

You can store the location of the data on the blockchain. Just define an asset in the Composer CTO field and give it a String property with the file location. There are code examples in the Playground for reading and writing to the autogenerated Asset Registry. You will also get a RESTful endpoint to read and write this data.