ba3de2af58
https://github.com/penberg/limbo/pull/321 recently fixed an error with register allocation order concerning binary expressions in `translate_condition_expr`. I noticed we had the same bug in `translate_expr` as well, and this led into noticing that our implementation of `Insn::Function` diverges from SQLite in that it doesn't provide a context object that keeps track of how many arguments the function call has. Not having the arg count available at runtime means that e.g.: ``` do_execsql_test length-date-binary-expr { select length(date('now')) = 10; } {1} ``` Returned 0 instead of 1, because at runtime another register was already allocated, and `date()` was implemented like this: ``` Func::Scalar(ScalarFunc::Date) => { let result = exec_date(&state.registers[*start_reg..]); // all registers starting from start_reg state.registers[*dest] = result; state.pc += 1; } ``` SQlite bytecode engine docs for Function say: > Invoke a user function (P4 is a pointer to an sqlite3_context object that contains a pointer to the function to be run) with arguments taken from register P2 and successors. The number of arguments is in the sqlite3_context object that P4 points to. Accordingly, this PR implements a `FuncCtx` struct that contains a `Func` and `arg_count` (usize). Reviewed-by: Pere Diaz Bou <pere-altea@hotmail.com> Closes #323
Limbo
Limbo is a work-in-progress, in-process OLTP database management system, compatible with SQLite.
Features
- In-process OLTP database engine library
- Asynchronous I/O support with
io_uring - SQLite compatibility (status)
- SQL dialect support
- File format support
- SQLite C API
- JavaScript/WebAssembly bindings (wip)
Getting Started
Installing:
curl --proto '=https' --tlsv1.2 -LsSf \
https://github.com/penberg/limbo/releases/latest/download/limbo-installer.sh | sh
Limbo is currently work-in-progress so it's recommended that you either use the sqlite3 program to create a test database:
$ sqlite3 database.db
SQLite version 3.42.0 2023-05-16 12:36:15
Enter ".help" for usage hints.
sqlite> CREATE TABLE users (id INT PRIMARY KEY, username TEXT);
sqlite> INSERT INTO users VALUES (1, 'alice');
sqlite> INSERT INTO users VALUES (2, 'bob');
or use the testing script to generate one for you:
pipenv run ./testing/gen-database.py
You can then start the Limbo shell with:
$ limbo database.db
Welcome to Limbo SQL shell!
> SELECT * FROM users LIMIT 1;
|1|Cody|Miller|mhurst@example.org|525.595.7319x21268|33667 Shaw Extension Suite 104|West Robert|VA|45161|`
Developing
Run tests:
cargo test
Test coverage report:
cargo tarpaulin -o html
Run benchmarks:
cargo bench
Run benchmarks and generate flamegraphs:
echo -1 | sudo tee /proc/sys/kernel/perf_event_paranoid
cargo bench --bench benchmark -- --profile-time=5
FAQ
How is Limbo different from libSQL?
Limbo is a research project to build a SQLite compatible in-process database in Rust with native async support. The libSQL project, on the other hand, is an open source, open contribution fork of SQLite, with focus on production features such as replication, backups, encryption, and so on. There is no hard dependency between the two projects. Of course, if Limbo becomes widely successful, we might consider merging with libSQL, but that is something that will be decided in the future.
Publications
- Pekka Enberg, Sasu Tarkoma, Jon Crowcroft Ashwin Rao (2024). Serverless Runtime / Database Co-Design With Asynchronous I/O. In EdgeSys ‘24. [PDF]
- Pekka Enberg, Sasu Tarkoma, and Ashwin Rao (2023). Towards Database and Serverless Runtime Co-Design. In CoNEXT-SW ’23. [PDF] [Slides]
Contributing
We'd love to have you contribute to Limbo! Check out the contribution guide to get started.
License
This project is licensed under the MIT license.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Limbo by you, shall be licensed as MIT, without any additional terms or conditions.