MacroDB
This is a crate that lets you automatically generate code for an in-memory database in Rust. It supports indexes, including unique indexes, as well as foreign keys. It can use HashMap as well as BTreeMap for the indices.
On a high level, the crate works by having you define a database struct that contains the tables and all of the indices, and then invoking the macro to generate appropriate insertion, update and deletion methods.
There is no support for transactions, concurrency (aside from the usual Rust semantics of having either multiple readers or a single writer) or persistence.
Benchmarks
The speed of the generated database depends on the data type that you select (BTreeMap or HashMap) and on the number of indices. The repository contains a synthetic benchmark that performs tests on a table with two indices and one unique index. On a MacBook Air M2, it can perform more than a million insertions per second.
| Data types | Operations | Count | Time (ms) | Throughput (Melem/s) |
|---|---|---|---|---|
| BTreeMap, BTreeSet | Insert | 1,000,000 | 564.26 | 1.7722 |
| BTreeMap, BTreeSet | Update | 1,000,000 | 1,033.50 | 0.9676 |
| BTreeMap, BTreeSet | Delete | 1,000,000 | 352.04 | 2.8406 |
| HashMap, HashSet | Insert | 1,000,000 | 807.63 | 1.2382 |
| HashMap, HashSet | Update | 1,000,000 | 1,319.20 | 0.7580 |
| HashMap, HashSet | Delete | 1,000,000 | 789.22 | 1.2528 |
This benchmark can be recreated by setting the insertion, update and deletion counts in benches/single_table.rs to one million and running cargo bench.
Example
See examples/ in this repository.
License
MIT, see LICENSE.md