Some concrete examples: 1. Yugabyte's relational query layer sits on top of a document store (DocDB): https://www.yugabyte.com/blog/how-we-built-a-high-perform

Some concrete examples: 1. Yugabyte's relational query layer sits on top of a document store (DocDB): https://www.yugabyte.com/blog/how-we-built-a-high-performance-document-store-on-rocksdb/ https://www.yugabyte.com/blog/how-we-built-a-high-performanc.... 2. You can put documents in a PostgreSQL JSON(B) column.