QuillSQL

An educational Rust RDBMS for cmu15445-style teaching (BusTub-inspired)

✨ Highlights

• Clean architecture: SQL → Logical Plan → Physical Plan → Volcano executor
• Transaction control: BEGIN/COMMIT/ROLLBACK, SET TRANSACTION, SET SESSION TRANSACTION, enforced READ ONLY, row/table locks
• B+Tree index: OLC readers, B-link pages, latch crabbing, range scan iterator
• Buffer manager: LRU-K + TinyLFU, WAL-aware dirty tracking, prefetch API, background writer
• Asynchronous storage: Dispatcher + io_uring worker pool for data pages, plus a buffered WAL runtime with cached segment handles for sequential log I/O
• Streaming / Prefetch: Large sequential scans bypass the cache via a small direct I/O ring buffer; targeted prefetch warms hot paths without pins
• WAL & Recovery (ARIES-inspired): FPW, logical heap/index records, DPT, chained CLR, per-transaction undo chains, idempotent replays
• Information schema: information_schema.schemas, tables, columns, indexes
• Docs: 📖 Read the Book Online

Demo

Built-in web TTY — commands mirror our SQL test suite.

• Run cargo run --bin server and open http://127.0.0.1:8080
• Commands: help, docs, doc <name>, examples, example <name>, github, profile
• Example scripts are pulled straight from src/tests/sql_example/

🎓 Teaching & Research Friendly

• Clear module boundaries, suitable for classroom assignments and research prototypes. Inspired by CMU 15-445 BusTub with strengthened WAL/Recovery, observability, and centralized configuration.
• Pluggable pieces: buffer pool, index, WAL, and recovery are decoupled for side-by-side experiments.
• Readability-first: simple, pragmatic code with minimal hot-path allocations.

🚀 Quick Start

cargo run --bin client

# or open a persistent DB file
cargo run --bin client -- --file my.db

# start web server (http://127.0.0.1:8080)
cargo run --bin server

# specify data file and listening addr
QUILL_DB_FILE=my.db QUILL_HTTP_ADDR=0.0.0.0:8080 cargo run --bin server --release

# batch API (optional)
curl -XPOST http://127.0.0.1:8080/api/sql_batch -H 'content-type: application/json' \
     -d '{"sql": "SHOW TABLES; EXPLAIN SELECT 1;"}'

Sample session:

CREATE TABLE t(id INT, v INT DEFAULT 0);
INSERT INTO t(id, v) VALUES (1, 10), (2, 20), (3, 30);

SELECT id, v FROM t WHERE v > 10 ORDER BY id DESC LIMIT 1;

SHOW DATABASES;
SHOW TABLES;

EXPLAIN SELECT id, COUNT(*) FROM t GROUP BY id ORDER BY id;

🧱 Supported SQL

• Data types

  • BOOLEAN, INT8/16/32/64, UINT8/16/32/64, FLOAT32/64, VARCHAR(n)

• CREATE TABLE

  • Column options: NOT NULL | DEFAULT <literal>
  • Example:

    CREATE TABLE t(
      id INT64 NOT NULL,
      v  INT32 DEFAULT 0
    );
    

• CREATE INDEX

  • Example:

    CREATE INDEX idx_t_id ON t(id);
    

• DROP

  • DROP TABLE [IF EXISTS] <name>
  • DROP INDEX [IF EXISTS] <name>
  • Example:

    DROP INDEX IF EXISTS idx_orders_user_id;
    DROP TABLE orders;
    

• INSERT

  • INSERT INTO ... VALUES (...) and INSERT INTO ... SELECT ...

• SELECT

• Projection: columns, literals, aliases

• FROM: table | subquery (FROM (SELECT ...)) — alias not yet supported

• WHERE: comparison/logical operators = != > >= < <= AND OR

• GROUP BY: aggregates COUNT(expr|*), AVG(expr)

• ORDER BY: ASC|DESC, supports NULLS FIRST|LAST

• LIMIT/OFFSET

• JOIN: INNER JOIN (with ON condition), CROSS JOIN

• UPDATE

  • UPDATE t SET col = expr [, ...] [WHERE predicate]

• DELETE

  • DELETE FROM t [WHERE predicate]

• SHOW

• SHOW DATABASES; (rewritten to SELECT schema FROM information_schema.schemas)

• SHOW TABLES; (rewritten to SELECT table_name FROM information_schema.tables)

• EXPLAIN

  • EXPLAIN <statement> returns a single column named plan with multiple lines showing the logical plan tree

⚠️ Current Limitations

• Not yet supported: ALTER, predicate locking.
• Not implemented: outer joins (Left/Right/Full), arithmetic expressions, table/subquery aliases
• ORDER BY DESC / NULLS FIRST|LAST currently affects sorting only (not storage layout)

🧪 Testing

cargo test -q

⚙️ Configuration

Minimal environment variables (runtime only)

• PORT: bind port (overrides the port of QUILL_HTTP_ADDR)
• QUILL_HTTP_ADDR: listen address (default 0.0.0.0:8080)
• QUILL_DB_FILE: path to database file (uses a temp DB if unset)
• QUILL_DEFAULT_ISOLATION: default session isolation (read-uncommitted, read-committed, repeatable-read, serializable)
• RUST_LOG: log level (e.g., info, debug)

Programmatic options live in quillsql::config (see docs) — build DatabaseOptions with WalOptions, BufferPoolConfig, BTreeConfig, etc., and pass into Database::new_*_with_options. Examples in the docs remain unchanged.

📦 Docker

# build
docker build -t quillsql:latest .

# run (ephemeral in-memory DB)
docker run --rm -p 8080:8080 quillsql:latest

# run with persistent file mounted
docker run --rm -p 8080:8080 -e QUILL_DB_FILE=/data/my.db -v $(pwd)/data:/data quillsql:latest

Includes sqllogictest-based cases:

• src/tests/sql_example/create_table.slt
• src/tests/sql_example/create_index.slt
• src/tests/sql_example/insert.slt
• src/tests/sql_example/show_explain.slt
• src/tests/sql_example/delete.slt

📚 Acknowledgements

• BustubX
• CMU 15-445/645 Database Systems

Community

Build. Break. Benchmark. Repeat.
QuillSQL has a Discord server for discussions, support, and experimental DB hacking.

What you can do here:

• 🧩 Design discussions — parser / executor / storage architecture
• 🧪 Experiments & prototypes — new operators, indexes, optimizer ideas, wild hacks
• 📈 Benchmarks & profiling — perf numbers, flamegraphs, regression hunts
• 📚 Research notes — papers, learning resources, implementation notes
• 🤝 Contributing help — “good first issue”, PR reviews, roadmap brainstorming

Join: https://discord.gg/dJqa4RYW65