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@@ -1,139 +1,27 @@ -#+TITLE: Sakura +#+TITLE: Relational Engine * About - -Sakura is a semantic-relational algebra engine inspired by -E. F. Codd's RM/T and D. McGoveran's (as understood by Fabian Pascal) -SRDM. It models relations in both intension and extension, providing -their manipulation as first-class elements of an algebra. - -* Motivation - -We believe the relational model was not ever fully implemented. The -fundamental necessity of expressing intent and binding meaning -enclosed to a conceptual model in data is seldom achieved by any -self-claimed relational database vendor. The emergence of different -physically concerned paradigms in the industry demonstrate not only a -large scale amnesia about fundamentals, but also a lethal -manifestation of problems that should not exist otherwise. The -relational data model as an applied theory is an universally rich and -concrete approach to reality that bases itself greatly in -moderate-realism applied to mathematics, as described in =An -Aristotelian Realist Philosophy of Mathematics: Mathematics as the -Science of Quantity and Structure= by J. Franklin. We believe that -unleashing the full potential of the relational model as refined over -the years despite overwhelming disregard of the industry as a whole, -will promote efficiency to a new scale never seen, that was very much -so cut short by relational pretenders and theoretically unsound -approaches. Our goal is to eliminate the application-database -distinction, while maintaining a clear separation between a first -order predicate logic algebra engine and a higher order predicate -logic decision engine (application) via an embedded data sublanguage -with Sakura as a possible auxiliary runtime. - -* Current State - -** What Works Today - -- Base finite relations: create, insert, retract, clear -- Built-in immutable/generated domains on database creation: - =integer=, =natural=, =rational=, =string=, =atom=, =term= -- Query DSL in =query_planner= and =repl=: - - base relation scan (using relation atom) - - =select=, =project=, =join=, =theta_join=, =sort=, =take=, =rename= - - =materialize= (plan-level, with caveats) -- Volcano-style iterator execution model (process-per-operator) -- Visual output modes in =visualizer= (table/tree/nested views) -- XML TCP server protocol commands: =QUERY=, =NEXT=, =CLOSE= - -** Known Gaps / Reliability Risks - -- Lack of constraints greater than 1OPs; -- =repl:start/0= is destructive: it calls =main:setup/0=, which recreates schema; -- =xml_server= =SCHEMA= path is currently fragile with constraints representation; -- Constraint/intension representation is not yet fully normalized across modules; -- Planner contains dual compilation styles (iterator path + relation path); -- Blocking operators (for example =sort=) over infinite relations can time out unless bounded with =take= first; -- There is currently no substantial automated test suite in-repo despite CI hooks; - -See =docs/reliability_roadmap.org= for the detailed remediation plan. - -* Architecture (High Level) - -- =src/operations.erl= :: core storage/versioning and iterator primitives -- =src/constraint.erl= :: domain constraints, inference, validation -- =src/generators.erl= :: infinite relation generators -- =src/relational_operators.erl= :: pure relation-to-relation algebra operators -- =src/query_planner.erl= :: tuple DSL parsing/validation/execution planning -- =src/repl.erl= :: shell-facing query convenience API -- =src/xml_server.erl= :: TCP/XML query interface -- =src/visualizer.erl= :: renderers for result tuples - -Data model records are defined in =include/operations.hrl=. - -* Query DSL - -Plans are Erlang tuples: - -- base relation: =employees= -- selection: ={select, employees, fun(T) -> maps:get(age, T) > 30 end}= -- projection: ={project, employees, [name, age]}= -- equijoin: ={join, employees, departments, dept_id}= -- theta join: ={theta_join, Left, Right, Pred2}= -- sort: ={sort, Plan, Comparator2}= -- take: ={take, Plan, N}= -- rename: ={rename, old_attr, new_attr, Plan}= - -* Running - -** Compile - -#+begin_src sh -rebar3 compile -#+end_src - -** REPL - -#+begin_src erlang -repl:start(). -DB = repl:example_db(). -repl:q(DB, employees). -repl:q(DB, {take, {sort, employees, - fun(A,B) -> maps:get(age,A) =< maps:get(age,B) end}, 3}). -#+end_src - -** XML Server (manual) - -Start server from Erlang shell, then send line commands over TCP: - -- =QUERY <plan>= -- =NEXT <session_id> <n>= -- =CLOSE <session_id>= - -* Design Intent - -Sakura aims to treat relations as algebraic manipulation units with both: - -- extension (actual tuples, finite or generated) -- intension (schema + constraints + derivation meaning) - -The current engine already exposes the extension side robustly for -many operations, despite the lack of constraints greater than 1OP. -The main active work is making intension handling fully consistent and -reliable across planners/operators/protocols. - -* Roadmap and Docs - -- =docs/reliability_roadmap.org= :: precise reliability + correctness roadmap -- =docs/code.org= :: code-oriented notes -- =docs/features.org= :: feature notes (may contain older planning context) -- =docs/constraints.org= :: constraint model notes - -* References - -- Codd, E. F. (1970), "A Relational Model of Data for Large Shared Data Banks" -- Codd, E. F. (1979), "Extending the Database Relational Model to Capture More Meaning" - -* License - -See =LICENSE=. +This is a relational engine. + +* Roadmap +- [ ] State + - [ ] Add the schema modifications to the commit state hash + - [ ] Save a history of the schema +- [ ] Filesystem [0/6] + - [ ] Durability + - [ ] Immutable storage + - [ ] ARIES + - [ ] Merkle construction per virtual file + - [ ] Branching + - [ ] Branch merge strategies [0/3] + - [ ] Selected merge + - [ ] Union merge + - [ ] Biased union merge +- [ ] Language [0/4] + - [ ] Lexer + - [ ] Parser + - [ ] AST + - [ ] Unification and query terms +- [ ] Server [0/2] + - [ ] Authentication + - [ ] Multi-client coordination |