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@@ -2,9 +2,21 @@ * About -Domino is a **Relational Algebra Engine** implements relational -algebra in its strict, theoretical form, adhering rigorously to the -principles of relational theory as articulated by E. F. Codd. +Domino is an *Extended Relational Database Engine* based on E. F. Codd's +RM/T (Relational Model/Tasmania, 1979). It implements relational algebra +in its strict, theoretical form while extending it to capture more of the +meaning of data through semantic modeling concepts. + +** Theoretical Foundation + +The engine builds upon two seminal works by E. F. Codd: + +1. *"A Relational Model of Data for Large Shared Data Banks"* (1970) — + The foundation of relational theory +2. *"Extending the Database Relational Model to Capture More Meaning"* (1979) — + RM/T extensions for semantic modeling + +** Core Principles A relation is modeled as a set of tuples, each tuple being a set of attributes. Each attribute is a pairing of a name with a value drawn @@ -12,9 +24,99 @@ from a domain. All operations are defined on entire relations as sets, with no recourse to the compromises typical of SQL or other practical implementations. -The engine is intended as a study in correctness: each operation, from -projection to join, is executed in a manner consistent with the -classical definition of relational algebra. It is a platform for -exploring the consequences of relational theory in a low-level -programming context, providing both a tool for experimentation and a -concrete realization of the abstract model. +** What Makes Domino Extended? + +*** Content-Addressed Storage +Entities are identified by system-controlled *surrogates* — cryptographic +hashes (SHA-256) that provide permanent, unique identification. This +enables: +- Automatic deduplication +- Immutable versioning +- Merkle tree-based diffing +- Distributed synchronization + +*** Entity Types (RM/T) +Three fundamental entity classifications: +- *Kernel Entities* — Independent entities (e.g., Employee, Supplier) +- *Characteristic Entities* — Multi-valued properties (e.g., Job History) +- *Associative Entities* — Relationships as first-class entities + +*** Four Dimensions of Molecular Semantics +1. *Cartesian Aggregation* — Properties, characteristics, and associations +2. *Generalization* — Subtyping and inheritance hierarchies +3. *Cover Aggregation* — Collections and groupings (e.g., teams, convoys) +4. *Event Precedence* — Temporal ordering of events + +*** Immutable Architecture +All data structures are immutable. Every modification creates a new version +with a new hash, enabling: +- Temporal queries +- Audit trails +- Safe concurrent access +- Version control for data + +** Current Implementation + +*** What's Built +- Content-addressed storage with SHA-256 surrogates +- E-relations for entity type management +- P-relations for immediate properties +- Merkle tree integration for efficient versioning +- Volcano iterator model for lazy evaluation +- Transactional ACID operations via Mnesia +- Comprehensive EUnit test suite + +*** What's Planned +- Full relational algebra operators (σ, π, ⋈, ∪, ∩, −) +- Characteristic entities and CG-relation +- Associative entities and AG-relation +- Generalization hierarchies (UGI/AGI) +- Cover aggregation (KG-relation) +- Event precedence (US/AS/UP/AP) +- Extended operators (OUTER JOIN, MAYBE operators) +- RM/T catalog relations +- Null value handling (three-valued logic) +- Infinite relations (aleph₀) +- High-level query language + +** Design Philosophy + +The engine is intended as a study in correctness and semantic richness: +each operation is executed in a manner consistent with the classical +definition of relational algebra, while the RM/T extensions provide a +framework for capturing more meaning about entities, their properties, +and their relationships. + +It is a platform for exploring the consequences of relational theory in +a low-level programming context, providing both a tool for experimentation +and a concrete realization of Codd's vision for semantic data modeling. + +** Why RM/T? + +Most database systems today are compromises — they sacrifice theoretical +purity for practical performance. Domino takes a different approach: +implement the theory *correctly* first, then optimize. RM/T provides: + +- *Atomic Semantics* — What constitutes a minimal meaningful unit? +- *Molecular Semantics* — What larger clusters constitute meaningful units? +- *Systematic Design* — Principled approach to database schema design +- *Intelligent Behavior* — System understands more about data meaning + +** Documentation + +See =docs/= directory: +- =code.org= — Comprehensive code documentation +- =features.org= — Feature roadmap and RM/T extensions +- =ci.org= — Continuous integration setup + +** References + +- Codd, E. F. (1970). "A Relational Model of Data for Large Shared Data Banks." + /Communications of the ACM/ 13(6): 377-387. +- Codd, E. F. (1979). "Extending the Database Relational Model to Capture More Meaning." + /ACM Transactions on Database Systems/ 4(4): 397-434. +- Date, C. J. & Darwen, H. "Foundation for Future Database Systems: The Third Manifesto." + +** License + +See LICENSE file. |