Simple SQLite Clone in C

A lightweight SQLite-inspired database implementation in C, built for educational purposes. This project demonstrates fundamental database concepts including B-trees, paging, and basic SQL operations.

Demo

Features

• Custom REPL (Read-Eval-Print Loop) interface
• Basic SQL operations (INSERT and SELECT)
• B-tree data structure for efficient data storage and retrieval
• Persistent storage with a simple file-based approach
• Memory management with paging system
• Row-based storage format

Technical Specifications

• Row Structure:
  • ID (integer)
  • Username (varchar, max 32 chars)
  • Email (varchar, max 255 chars)
• B-tree Implementation:
  • Leaf nodes and internal nodes
  • Automatic node splitting when full
  • Parent pointer for tree traversal
• Page size: 4096 bytes
• Maximum pages: 100

Building the Project

To compile the project, use a C compiler (gcc recommended):

gcc -o db main.c

Usage

1. Start the database with a file name:

./db mydb.db

2. Available commands:

-- Insert a new record
insert 1 user1 user1@example.com

-- Select all records
select

-- Meta commands
.exit      -- Exit the program
.btree     -- Display the B-tree structure
.constants -- Show internal constants

Running Tests

The project includes RSpec tests. To run them:

1. Install Ruby and RSpec
2. Run the test suite:

rspec spec/main_spec.rb

Project Structure

• main.c: Main source code containing the database implementation
• spec/main_spec.rb: Test specifications
• .gitignore: Git ignore rules
• README.md: This documentation file

Implementation Details

The database is implemented with the following key components:

1. Pager: Handles reading/writing pages to disk
2. Table: Manages the database structure
3. Cursor: Abstracts the position in the table
4. B-tree: Implements the tree data structure for storing rows
5. Node: Represents leaf and internal nodes in the B-tree

Limitations

• Fixed schema (id, username, email)
• Basic SQL support (only INSERT and SELECT)
• No DELETE or UPDATE operations
• No transaction support
• Maximum 100 pages

Contributing

Feel free to submit issues and enhancement requests!

License

This project is open source and available under the MIT License.

Acknowledgments

This project is inspired by the "Let's Build a Simple Database" tutorial series by Connor Stack, implementing a SQLite clone from scratch in C. The tutorial provides an excellent step-by-step guide to understanding database internals by building one from the ground up.