How do blockchains and databases work together on utxo based blockchains?

[BetterWater]

Do you fellas and gals know any more examples where (a relational or non-relational) database is working together to make data presentable for the user from UTXO based blockchains such as bitcoin.

I don't know much but from what I understand CouchDB is used to store data from Hyperledger's Fabric. What does Ethereum use?


Reason for my question is because I am trying to write a paper (mainly to clarify for myself) how the blockchain is not here to replace databases as such but work together with them to reliably present immutable and decentralised data.