mojo-sqlite

SQLite for Mojo that returns the same rows as Python's sqlite3, byte for byte, and runs 2.7× faster on inserts and 4× to 5.5× faster on scans.

from sqlite import Database

def main() raises:
    var db = Database("jobs.db")
    var q = db.prepare("SELECT id, cmd FROM jobs WHERE prio >= ?")
    q.bind(1, 10)
    while q.step():
        print(q.int(0), q.text(1))

Install

Requires Mojo 1.2 and the system libsqlite3.so.0 (any Linux distribution has it). The library is loaded at run time, so no linker flags are needed.

Way	Command
Source path	mojo run -I path/to/mojo-sqlite/src app.mojo
Precompiled	mojo precompile src/sqlite -o sqlite.mojoc, then put it next to your code
Vendor	copy src/sqlite/ into your project

What you get

• Database: open, exec for scripts, prepare, begin/commit/rollback, changes, last_insert_rowid. Busy timeout 5 s by default.
• Statement: bind for Int, Int64, Float64, String, BLOBs (List[UInt8]) and bind_null, by position or by name (:prio, @prio, $prio); step, run, reset; typed column reads, is_null, type, name.
• text_view(col) and blob_view(col): read in place from sqlite's buffer, no copy.
• Errors carry sqlite's own message: sqlite: UNIQUE constraint failed: u.k (rc 19).

The API is in docs/api.md. The memory and speed design is in docs/design.md.

Performance

tests/bench.mojo against tools/bench_oracle.py: 200,000 inserts through one prepared statement in a transaction, then a full scan, on an on-disk WAL database. Three runs each.

	insert	scan	peak RSS
Python sqlite3	216 to 226 ms	98 to 99 ms	14.5 MB
mojo-sqlite, text()	80 to 82 ms	25 to 29 ms	15.4 MB
mojo-sqlite, text_view()	79 to 82 ms	18 to 23 ms	15.2 MB

The RSS difference is the Mojo runtime: an empty Mojo program uses 11.6 MB.

Limits

• One connection per Database. Do not share a Database or Statement across threads.
• Linux only: the library is loaded as libsqlite3.so.0.

Check

scripts/ci.sh

It runs uv sync, then scripts/check.sh. CI runs the same script on every push, on Ubuntu 24.04 (sqlite 3.45); it also passes on sqlite 3.54.

Every SQL file in tests/cases/ runs through this library and through Python sqlite3 with the same system libsqlite3, and the outputs must be identical: integers, the exact bits of every float, text with tabs and newlines, NULL, BLOBs as hex, and which statements fail. Then tests/api.mojo covers lifetimes, bind slots, errors and statement reuse.

For coding agents

skills/mojo-sqlite/SKILL.md tells an agent how to use the library and what to avoid.

Licence

Apache-2.0, see LICENSE.