Chryso

Chryso is a Calcite-style SQL parser + optimizer engine in Rust. It focuses on a clean, modular pipeline (AST -> logical plan -> Cascades optimizer -> physical plan -> adapter) and keeps the core engine execution-agnostic.

Features

• Multi-dialect SQL parsing (Postgres + MySQL first)
• Cascades optimizer with logical and physical rules
• Cost and statistics hooks via ANALYZE and a lightweight catalog
• Adapter-based execution (DuckDB first, Velox next)

Status

• Parser, planner, and core Cascades skeleton are implemented
• DuckDB adapter translates physical plans to SQL and executes simple queries/DML
• CI builds and tests with and without the DuckDB feature

Workspace Layout

crates/
  core/       AST, errors, formatting helpers
  parser/     Dialect-aware parser
  planner/    Logical/physical plan definitions + builder
  optimizer/  Cascades skeleton (memo, rules, cost)
  metadata/   Catalog, stats cache, analyze hooks
  adapter/    Execution adapters (DuckDB, mock)
  parser_yacc/ Yacc scaffold (validation)
src/
  lib.rs      Facade crate re-exports
  bin/
    chryso-cli.rs

Quick Start

Run the CLI (mock adapter by default):

cargo run --bin chryso-cli

Run the DuckDB demo:

cargo run --example duckdb_demo --features duckdb

Tests

All tests:

cargo test

With DuckDB:

cargo test --features duckdb

Plan snapshot tests:

• Inputs: tests/testdata/plan/case1/in.json
• Expected outputs: tests/testdata/plan/case1/out.json

Record snapshots:

CHRYSO_RECORD=1 cargo test --test plan_snapshot

Docs

• docs/ARCHITECTURE.md for the planning pipeline and module overview
• docs/RULES.md for rule conventions and current rule set
• docs/ADAPTERS.md for adapter design
• docs/ROADMAP.md for milestones and TODOs

Roadmap (Highlights)

• Parser: expand dialect coverage and AST compatibility
• Logical rewrites: constant folding and predicate simplification
• Cascades: richer rule library and join order enumeration
• Costing: integrate ANALYZE stats into cost models
• Physical planning: enforcers and required properties
• Adapters: stabilize DuckDB, then add Velox

License

TBD.