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https://github.com/apllodb/apllodb
A RDBMS with Immutable Schema feature
https://github.com/apllodb/apllodb
database immutable rdbms rust
Last synced: 3 months ago
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A RDBMS with Immutable Schema feature
- Host: GitHub
- URL: https://github.com/apllodb/apllodb
- Owner: apllodb
- License: apache-2.0
- Created: 2019-01-31T07:18:00.000Z (almost 6 years ago)
- Default Branch: main
- Last Pushed: 2021-10-13T09:50:10.000Z (about 3 years ago)
- Last Synced: 2024-07-28T17:44:41.281Z (4 months ago)
- Topics: database, immutable, rdbms, rust
- Language: Rust
- Homepage:
- Size: 1.17 MB
- Stars: 33
- Watchers: 4
- Forks: 2
- Open Issues: 20
-
Metadata Files:
- Readme: README.md
- License: LICENSE-APACHE
Awesome Lists containing this project
README
# apllodb
[](https://github.com/apllodb/apllodb/actions/workflows/ci.yml)
[](https://codecov.io/gh/apllodb/apllodb)
[](https://github.com/apllodb/apllodb/blob/main/LICENSE-MIT)
[](https://github.com/apllodb/apllodb/blob/main/LICENSE-APACHE)
apllodb is a RDBMS purely written in Rust.
It has the following distinguished features:
- **Plugable storage engine:**
- Implementing apllodb's storage engine is unambiguous. Your storage engine crate just depends on `apllodb-storage-engine-interface` crate and implements `StorageEngine` trait (and its associated types).
- apllodb's default storage engine is **Immutable Schema** Engine (`apllodb-immutable-schema-engine`). This engine never deletes / requires to delete old records on `UPDATE`, `DELETE`, even on `ALTER TABLE` and `DROP TABLE`.
Also, we have plan to develop the following unique features:
- Ambiguous data ("about 100 years ago", for example) and query toward them.
- Algebraic data type as SQL types.
## Getting Started
Here shows how to build & run `apllodb-cli` and execute simple SQLs.
You are supposed to have installed [Cargo](https://github.com/rust-lang/cargo).
```bash
git clone [email protected]:eukarya-inc/apllodb.git
cd apllodb
cargo build
./target/debug/apllodb-cli
🚀🌙 SQL> # Press Ctrl-D to exit
```
```sql
🚀🌙 SQL> create database my_db;
🚀🌙 SQL> use database my_db;
🚀🌙 SQL> create table t (id integer, name text, primary key (id));
-- Oops! You need open transaction even for DDL.
🚀🌙 SQL> begin;
🚀🌙 SQL> create table t (id integer, name text, primary key (id));
🚀🌙 SQL> select id, name from t;
0 records in total
🚀🌙 SQL> insert into t (id, name) values (1, "name 1");
🚀🌙 SQL> insert into t (id, name) values (2, "name 2");
🚀🌙 SQL> select id, name from t;
t.id: 2 t.name: "name 2"
t.id: 1 t.name: "name 1"
2 records in total
🚀🌙 SQL> commit;
```
## Try Immutable Schema
Current core feature of apllodb is **Immutable Schema**.
Immutable Schema consists of Immutable **DDL** and Immutable **DML**.
With Immutable DDL, any kind of `ALTER TABLE` or `DROP TABLE` succeed without modifying existing records.
For example, if `t` has 1 or more records,
```sql
ALTER TABLE t ADD COLUMN c_new INTEGER NOT NULL;
```
would cause error in many RDMBSs because existing records cannot be NULL but this ALTER does not specify default value for `c_new`.
Immutable Schema preserves existing records in an old **version** and creates new version.
```sql
t (version1)
| id | c_old |
|----|-------|
| 1 | "a" |
| 2 | "b" |
ALTER TABLE t ADD COLUMN c_new INTEGER NOT NULL;
t (version1) t (version2)
| id | c_old | | id | c_old | c_new |
|----|-------| |----|-------|-------|
| 1 | "a" |
| 2 | "b" |
INSERT INTO t (id, c_old, c_new) VALUES (3, "c", 42);
t (version1) t (version2)
| id | c_old | | id | c_old | c_new |
|----|-------| |----|-------|-------|
| 1 | "a" | | 3 | "c" | 42 |
| 2 | "b" |
INSERT INTO t (id, c_old) VALUES (4, "d");
t (version1) t (version2)
| id | c_old | | id | c_old | c_new |
|----|-------| |----|-------|-------|
| 1 | "a" | | 3 | "c" | 42 |
| 2 | "b" |
| 4 | "d" |
```
As the above example shows, DML like `INSERT` automatically choose appropriate version to modify.
To learn more about Immutable Schema, check [this slide](https://docs.google.com/presentation/d/1C6YsUNfMb4cioc2KWMwO2-85IpNfq558-IjxJh6LvPg/edit?usp=sharing) ([Japanese version](https://docs.google.com/presentation/d/1pV287_Q5LDbY9GWn3lK1iJdFz9rTnMsbmQ0a98YUY90/edit?usp=sharing)).
Currently, both Immutable DDL and Immutable DML are under development and some SQLs do not work as expected.
[doc/immutable-ddl-demo.sql](doc/immutable-ddl-demo.sql) is a working example of Immutable DDL. Try it by copy-and-paste to `apllodb-cli`.
## Development
This repository is a [multi-package project](https://doc.rust-lang.org/edition-guide/rust-2018/cargo-and-crates-io/cargo-workspaces-for-multi-package-projects.html).
Many useful tasks for development are defined in `Makefile.toml`. Install [cargo-make](https://github.com/sagiegurari/cargo-make) to participate in apllodb's development.
```bash
# (clone repository)
cd apllodb
cargo make test
# (write your code)
cargo make build
cargo make test
# (before making pull-request)
cargo make format
cargo make lint
# (generate rustdoc)
cargo make doc
```
## Architecture
We refer to ["Architecture of a Database System"](https://dsf.berkeley.edu/papers/fntdb07-architecture.pdf) to set boundaries between each components (crates).
The following diagram, similarly illustrated to Fig. 1.1 of the paper, shows sub-crates and their rolls.
(Box with gray text are unimplemented roles)
Entry points in `apllodb-server`, `apllodb-sql-processor`, and `apllodb-storage-engine-interface` are **async** functions so clients can run multiple SQLs at a time.
`apllodb-server` is the component to choose storage engine to use. `apllodb-immutable-schema-engine::ApllodbImmutableSchemaEngine` is specified at compile-time (as type parameter) for now.
Currently, apllodb has a single client; `apllodb-cli`. `apllodb-cli` runs from a shell, takes SQL text from stdin, and outputs query result records (or error messages) to stdout/stderr.
Also, `apllodb-cli` works as single-process database. `apllodb-server` currently does not run solely.
Of course we have plan to:
- Split server and client.
- Provides client library for programming languages (Rust binding may be the first one).
## License
Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or [MIT license](LICENSE-MIT) at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in apllodb by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.