Coding a V1 of an in-memory relational database

[Vivek Dehariya]

Hello,

I am trying to code up an in-memory RDBMS in java with a basic set of entities such as database, tables ( rows/columns) , data types, indexes, constraints, and minimal functionalities around CRUD operations. I have tried to take a look at some codebases like H2, HSQL but it feels very overwhelming to understand how should a basic low-level design look like for my subset of requirements. If someone can help me with a lead on a good resource for starting off or link to some source code that I can go through it would be helpful. My main criteria is to code it in an object-oriented and extensible manner so I can add more functionalities later on in a simple fashion. Please guide me in some direction.

Thanks,

Vivek