I once wrote an ECS for a game and it was literally a database without WHERE clauses (write your own if statements, indexes are too expensive). Each component w

I once wrote an ECS for a game and it was literally a database without WHERE clauses (write your own if statements, indexes are too expensive). Each component was a table and your systems used left joins or inner joins to query the tables. The join algorithm was quite simple as well. Just a binary search to find the next element by its ID.