Joedb is a minimalist in-memory database, that allows directly manipulating tables stored in native type-safe C++ containers. It comes with a server and a network protocol that makes sharing data between machines as easy as sharing variables between threads. Joedb also allows writing data to files with proper crash-safe concurrent ACID transactions.
The diagram below illustrates how the system works: joedbc, the joedb
compiler, reads the database schema and produces classes that can be used to
manipulate files:
Other systems such as protocol buffers provide similar type-safe mechanisms for serializing structured data, but are missing key properties of a database, such as concurrency, transactions, and incremental crash-safe updates. Joedb can offer all these features by storing data as a journal of transactions. The whole data history is stored, so it is possible to re-create any past state of the database. Joedb also has a network protocol, and can operate a bit like git for structured data.
To give an indication of joedb's simplicity, the table below shows the size of
joedb's source code compared to some other libraries. Lines of code are counted
with wc -l. Compressed size is the size in bytes after removing comments
and compressing with gzip. These numbers were measured on 2024-07-28 on the
main branch.
| Software | Lines of code | Compressed size | Notes |
|---|---|---|---|
| joedb | 19,288 | 72,268 | without tests |
| nlhohmann/json | 24,941 | 87,168 | single include |
| boost/json | 37,609 | 123,229 | |
| SQLite | 258,281 | 1,067,983 | sqlite3.c amalgamation |
| PostgreSQL | 1,513,329 | 5,250,316 | content of src dir, without tests |
So joedb is an extremely simple low-level foundation for sharing relational data. It would be possible to build a SQL database on top of it, but it is already very convenient by itself.
For more information, please take at a look at the documentation.