minisqlite

A reimplementation of SQLite in Rust: the SQL dialect, the query planner and executor, transactions, and the storage engine, down to the official on-disk file format. It opens database files that sqlite3 wrote and writes files that sqlite3 reads back.

It is a library with a deliberately small surface: one type, four methods. The implementation is about 200,000 lines of Rust across 14 crates, with 5,650 tests, one external dependency (elsa, for the page cache), and no unsafe in library code.

use minisqlite::{Connection, Value};
use std::path::Path;

let mut db = Connection::open(Path::new("app.db"))?; // or Connection::open_in_memory()

db.execute(
    "CREATE TABLE users(id INTEGER PRIMARY KEY, name TEXT NOT NULL);
     INSERT INTO users(name) VALUES ('alice'), ('bob');",
)?;

let r = db.query("SELECT id, name FROM users WHERE name LIKE 'a%'")?;
assert_eq!(r.columns, ["id", "name"]);
assert!(matches!(&r.rows[0][1], Value::Text(name) if name == "alice"));

That is the whole public API: Connection::{open, open_in_memory, execute, query}, plus the re-exported Value, Row, QueryResult, and Error types. execute runs any number of ;-separated statements; query returns the last statement's result set. Value has exactly the five SQLite storage classes: Null, Integer(i64), Real(f64), Text(String), Blob(Vec). There is no CLI, no C API, and no prepared-statement interface.

Build and test with a recent stable toolchain (the workspace uses edition 2024):

cargo build --workspace
cargo test  --workspace    # 5,650 tests, about 90 s
cargo bench                # scalability + durability measurement harness

File compatibility

The on-disk format is SQLite's format 3, in both directions:

$ sqlite3 app.db "CREATE TABLE t(x); INSERT INTO t VALUES ('written by sqlite3')"
$ # ... open app.db with minisqlite, read that row, INSERT 'written by minisqlite' ...
$ sqlite3 app.db "SELECT x FROM t; PRAGMA integrity_check"
written by sqlite3
written by minisqlite
ok

This includes the hard cases: WAL databases with a live -wal file, UTF-16LE and UTF-16BE text encodings, auto-vacuum databases with pointer-map pages, overflow chains, freelists, page sizes from 512 to 65536 bytes, and databases with reserved bytes at the end of each page. The format tes