There are 2 repositories under hybrid-database topic.
:gem: Flexible, high performance IMDB & disk hybrid database written in Go. Features a brand-new modernistic query language and deep schema validation.
The flat-file, in-memory, remote-sync or hybrid db that is as lightning fast as you configure it to be.
Meta data extraction from various databases
Create a schema and load data into MariaDB HTAP.
Hybrid Relational-Database/NOSQL-Datastore