Thank you all, I've tried to read all the comments. I think I have to clarify the questions I asked: 1. Is related to our upcoming startup, we chose MySQL + R

Thank you all, I've tried to read all the comments. I think I have to clarify the questions I asked: 1. Is related to our upcoming startup, we chose MySQL + Redis, but some said use PostgreSQL (However, my friend explained that MySQL before v8 was weak and after v8 has tried to come back to its salad days, this is why he chose MySQL) 2-3-4: In the industry, especially in the industry I'm active, Digital Built Environment Industry, there's a lot of invaluable schemas, especially XML(XMI) that I feel "these schemas convert structured data to semi-structured data" which is not good and efficient For this reason, I'm thinking of SQL (Server) and SQLite (File) to preserve structured data There's a vitally important schema in the built environment industry called Industry Foundation Classes (IFC) [1] which is based on EXPRESS/STEP and also has XML(XMI) schema too, but I want to convert the schema to SQL and SQLite A friend did an invaluable job and after years introduced a correct method to convert it to SQL [2][3] but don't have any idea of developing the schema based on SQLite [4] that will accelerate the IFC development [1] https://www.buildingsmart.org/about/what-is-openbim/ifc-introduction/ https://www.buildingsmart.org/about/what-is-openbim/ifc-intr... [2] https://forums.buildingsmart.org/t/ifc-for-relational-databases-ifcsql/1524 https://forums.buildingsmart.org/t/ifc-for-relational-databa... [3] https://forums.buildingsmart.org/t/store-modify-and-retrieve-ifc-data-with-ifcsql/1558 https://forums.buildingsmart.org/t/store-modify-and-retrieve... [4] https://forums.buildingsmart.org/t/ifc-sqlite-project/1359 https://forums.buildingsmart.org/t/ifc-sqlite-project/1359