MiniSQL

Project Structure

• client - REPL client for connecting to the server
• server - MiniSQL server
• minisql - SQL AST interpreter
• parser - SQL parser
• proto - Implementation of subset of PostgreSQL protocol

Requirements

• Rust + Cargo with version >= 1.74.0 (using impl in return statements)
• Optional: psql cli for testing the server

Usage

Running the server

cargo run -p server -- [OPTIONS] --folder <FOLDER>

Options:
  -a, --address <ADDRESS>  IP address for the server to listen on [default: 127.0.0.1]
  -p, --port <PORT>        Port for the server to listen on [default: 5432]
  -f, --folder <FOLDER>    Path to the folder for database data
  -t, --throttle <DELAY>   Delay between rows in milliseconds
  -h, --help               Print help

This will start the server listening on <ADDRESS>:<PORT> and load the state from <FOLDER>. If the <FOLDER> does not exist, it will be created.

Demo Database

Commands that set up a database with demo data are available in demo-1.sql, demo-2.sql, and demo-3.sql.

These files showcase the following things:

• demo-1.sql: small tables that handle Unicode and make use of the Optional type
• demo-2.sql: a bigger (1000 rows) table with realistic data
• demo-3.sql: a big (10,000 rows) table with simple data (was easier to generate)

See comments in these files for details.

Running the client

cargo run -p client -- [OPTIONS]

Options:
  -p, --port <PORT>          Port number of the server [default: 5432]
      --host <HOST>          Host name or IP address of the server [default: 127.0.0.1]
      --username <USERNAME>  User name [default: "minisql user"]
  -h, --help                 Print help

This will start a REPL client that connects to the server at <HOST>:<PORT> and authorizes with <USERNAME>. SQL queries can be entered line by line. The client will print the result of each query.

To exit the REPL client, enter exit or quit.

Features

• SQL must be on single line, in UPPERCASE, as it should be. The ; at EOL is optional.
• Supported operations: CREATE TABLE, CREATE INDEX, SELECT, INSERT, DELETE
• Supported data types: UUID, STRING, INT, NUMBER
• Supported subset of PostgreSQL protocol, without authentication and simple query flow

Operations

CREATE TABLE

• Every table requires one column with type UUID as PRIMARY KEY

CREATE TABLE <TableName> (<ColumnName> <DataType>, ...);

With the demo database, this can be used to create a new table:

CREATE TABLE games (id UUID PRIMARY KEY, name STRING, year INT, price NUMBER);

CREATE INDEX

• Indexing is not supported for the NUMBER data type

CREATE INDEX <IndexName> ON <TableName> (<ColumnName>);

With the demo database, this can be used to create a new index:

CREATE INDEX CarsYear ON cars (year);

SELECT

• WHERE clause is optional and only equality is supported
• All columns can be selected with *

SELECT <ColumnName>, ... FROM <TableName> [WHERE <ColumnName> = <Value>];

With the demo database, this can be used to select all cars with year 2001:

SELECT * FROM cars WHERE year = 2001;

INSERT

INSERT INTO <TableName> (<ColumnName>, ...) VALUES (<Value>, ...);

With the demo database, this can be used to insert a new user:

INSERT INTO users (id, name, surname, email) VALUES (u12345, "John", "Doe", "johhny.trucker@seznam.cz");

DELETE

• WHERE clause is optional and only equality is supported

DELETE FROM <TableName> [WHERE <ColumnName> = <Value>];

With the demo database, this can be used to delete all users with name Christina:

DELETE FROM users WHERE name = "Christina";

Data Types

• UUID - special integer prefixed with u, e.g. u12345
• STRING - string enclosed in double quotes, e.g. "Hello World"
• INT - integer, e.g. 12345
• NUMBER - floating point number, e.g. 123.45
• Option(Something) - optional type, e.g. Some("james.stuart@gmail.com") or None

Testing with psql

Thanks to the subset of PostgreSQL protocol implemented in proto, the server can be tested with psql, which offers REPL client similar to the client crate:

psql -h <HOST> -p <PORT>