ExplainDB: A Database System Built for Understandability

ExplainDB is a didactic DBMS implemented in Python, designed for readability rather than speed. It includes a full storage hierarchy, B⁺-tree and bitmap indexes, Bloom filters, MVCC with journaling, query operators, external merge sort, and join-order optimization. The repository provides Jupyter notebooks that walk through each concept, from data layout to Z-order curves, and can be run directly in the browser via Binder. Created by Prof. Dr. Jens Dittrich's group at Saarland University, it is licensed under AGPL-3.0.