QuillSQL

✨ 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 pool: LRU-K, pin/unpin with RAII guards, flush-on-evict
• Streaming scan: Large sequential scans bypass buffer pool via a small direct I/O ring buffer to avoid cache pollution
• WAL & Recovery (ARIES-inspired): FPW + PageDelta, DPT, chained CLR, per-transaction undo chains, idempotent replays
• Information schema: information_schema.schemas, tables, columns, indexes
• Now supports: SHOW DATABASES, SHOW TABLES, EXPLAIN, DELETE
• Docs: Architecture · Buffer Pool · B+ Tree Index · Disk I/O · WAL & Recovery · Transactions

🎓 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);
    

• 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: DROP, ALTER, MVCC, 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

Programmatic configs (centralized)

• Build DatabaseOptions { wal: WalOptions { .. } } and pass it to Database::new_*_with_options(..); WAL/scan are centrally managed by crate::config.
• Key structs: IOStrategy, IOSchedulerConfig, BufferPoolConfig, BTreeConfig, TableScanConfig, WalConfig/WalOptions.

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)

Example (Rust)

use std::sync::Arc;
use quillsql::config::{IOStrategy, IOSchedulerConfig, BufferPoolConfig, BTreeConfig, TableScanConfig};
use quillsql::storage::disk_manager::DiskManager;
use quillsql::storage::disk_scheduler::DiskScheduler;
use quillsql::buffer::buffer_pool::BufferPoolManager;

// Disk I/O backend: ThreadPool or Linux io_uring
let dm = Arc::new(DiskManager::try_new("my.db").unwrap());
let scheduler = Arc::new(DiskScheduler::new_with_strategy(
    dm.clone(),
    IOStrategy::IoUring { queue_depth: Some(256) }, // or ThreadPool { workers: Some(n) }
));

// Buffer pool
let bpm = Arc::new(BufferPoolManager::new_with_config(
    BufferPoolConfig { buffer_pool_size: 5000, ..Default::default() },
    scheduler.clone(),
));

// B+Tree iterator tuning (batch window & prefetch)
let btree_cfg = BTreeConfig { seq_batch_enable: true, seq_window: 32, ..Default::default() };
// Table scan tuning (streaming readahead)
let table_scan_cfg = TableScanConfig { stream_scan_enable: true, readahead_pages: 4, ..Default::default() };

// WAL config (centralized)
use quillsql::config::WalConfig;
let wal_cfg = WalConfig { segment_size: 16 * 1024 * 1024, sync_on_flush: true, ..Default::default() };

Notes

• io_uring is Linux-only; non-Linux will fall back to the thread pool.
• Streaming/RingBuffer optimizations are controlled via BTreeConfig / TableScanConfig instead of env vars.

📦 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