Taco-DB is a semester-long project for building a mini RDBMS (Relational DataBase Management System) written in C++. Topics vary across semesters but typically it covers storage (POSIX I/O, buffer management), data layout (record, page, heap/index files), query processing and optimization, and etc. This is frequently used as the course project for University at Buffalo CSE 4/562 Database Systems, and Penn State University CSE 541 Database Systems I.
This web page lists the current and historical versions of Taco-DB for UB CSE 4/562.