103 lines
2.7 KiB
Markdown
103 lines
2.7 KiB
Markdown
## Query Engine
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An experimental Rust project for building query-engine components.
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Right now the repository is centered on a chase-based reasoning core plus a
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small interactive frontend. The broader target shape is a query engine with
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clearer front-end, planning, optimization, and execution boundaries.
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### Current scope
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- Chase-based rule evaluation over facts, rules, and substitutions
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- Restricted-chase style materialization with active-trigger checks
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- Provenance-oriented explanations for derived answers
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- Script, REPL, and local web UI for experimentation
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### Intended direction
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The medium-term direction is to evolve this project from a copied
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`chase-rs` codebase into a more general query-engine playground with:
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- explicit front-end and parsing layers
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- internal planning representations
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- clearer separation between logical meaning and execution strategy
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- support for multiple query-engine experiments instead of only chase logic
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The current code does not yet implement a SQL front end, logical plan, or
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physical plan. The repository naming, docs, and user-facing surfaces now
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reflect that more honestly.
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### Quickstart
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#### Rust API
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```rust
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use query_engine::{Atom, Instance, Term, chase};
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use query_engine::chase::rule::RuleBuilder;
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let instance: Instance = vec![
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Atom::new("Parent", vec![Term::constant("alice"), Term::constant("bob")]),
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Atom::new("Parent", vec![Term::constant("bob"), Term::constant("carol")]),
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]
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.into_iter()
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.collect();
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let rule1 = RuleBuilder::new()
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.when("Parent", vec![Term::var("X"), Term::var("Y")])
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.then("Ancestor", vec![Term::var("X"), Term::var("Y")])
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.build();
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let rule2 = RuleBuilder::new()
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.when("Ancestor", vec![Term::var("X"), Term::var("Y")])
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.when("Parent", vec![Term::var("Y"), Term::var("Z")])
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.then("Ancestor", vec![Term::var("X"), Term::var("Z")])
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.build();
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let result = chase(instance, &[rule1, rule2]);
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assert!(result.terminated);
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assert_eq!(result.instance.facts_for_predicate("Ancestor").len(), 3);
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```
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#### CLI
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```bash
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cargo run -- repl
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cargo run -- gui
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cargo run -- script examples/scripts/ancestor.chase
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```
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#### REPL language
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```text
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fact Parent(alice, bob).
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rule Parent(?X, ?Y) -> Ancestor(?X, ?Y).
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run.
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query Ancestor(?X, ?Y)?
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explain Ancestor(alice, carol)?
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show facts
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show rules
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reset
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help
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```
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### Development
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For non-trivial changes, run:
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```bash
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cargo test
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cargo clippy --all-targets --all-features -- -D warnings
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cargo fmt --check
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```
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### Notes
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This repository is still centered on a rule-engine core. The longer-term goal
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is to grow it into a broader query-engine project without claiming SQL,
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logical-planning, or physical-planning support before those layers exist.
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### License
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This project is licensed under [BSD-3](LICENSE).
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