Relational algebra has been invented for fifty years. The difference between the application requirements and hardware environments of fifty years ago and today is very huge. Continuing to apply the theory of fifty years ago to solve today's problems, does it sound too outdated? However, this is the reality. Due to the large number of existing users and the lack of mature new technologies, SQL, based on relational algebra, is still the most important database language today. Although some improvements have been made in recent decades, the foundation has not changed. In the face of contemporary complex requirements and hardware environments, it is reasonable that SQL is incompetent.

And, unfortunately, this problem is at the theoretical level, and it won't help no matter how optimized it is in practice, it can only be improved in a limited way, not eradicated. Regrettably, most database developers do not think of this level, or, in order to take care of the compatibility of existing users, they do not intend to think about this level. As a result, the mainstream database industry has been going around in circles in this limited space.

There's a new programming language called SPL(structured process language)，Its theoretical basis is no longer the relational algebra, but something called discrete dataset.innovations against various deficiencies of relational algebra have been made to the discrete dataset.