LittleDB - Educational Database Management System

⚠️ Disclaimer:
This project was developed for educational purposes only as part of my Database II course at the School of Computer Science - UNSA.
It is not intended for production use.

The implementation was built from scratch in C++ to understand how a Database Management System (DBMS) works internally.

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🖼️ Diagrams

High-Level Architecture

System Diagram

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📖 References & Learning Resources

This project was inspired by and based on the following materials:

• Course: Carnegie Mellon University - 15-445/645 Database Systems (Spring 2024)
• Book: Database System Concepts (7th Edition)
  • Avi Silberschatz
  • Henry F. Korth
  • S. Sudarshan
• YouTube Playlist: CMU Database Systems

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📂 Project Overview

LittleDB is a miniature DBMS that implements the main building blocks of a database system, including:

• Buffer Manager
• Disk Manager
• Query Execution
• Storage Organization
• Indexing (B+ Tree)
• Interactive Console

It is designed to simulate how modern databases manage storage, memory, and queries.

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⚙️ Main Features

🗄️ Storage & Disk Management

• Creation of a custom disk structure
• Persistent storage with LOAD functionality to recover data between executions
• HeapFile management for free blocks
• Disk sector and block allocation for relations

🧠 Buffer Management

• Frames with pinning/unpinning, dirty flags, and reference bits
• Page abstraction with support for adding/deleting records
• Replacement Policies:
  • Least Recently Used (LRU)
  • Clock Algorithm
• Functions to load, update, delete, and persist pages

🌳 Indexing

• B+ Tree implementation supporting:
  • Insertions
  • Searches
  • Deletions (leaf and internal nodes)
  • DOT export for visualization

📋 Query Execution

• DatabaseMediator to connect buffer, disk, and query layers
• Insert, select, and delete operations
• CSV import support
• Schema validation and management

💻 Interactive Console

• Execute SQL-like commands:
  • createTable
  • insertSchema
  • selectTable
  • showTable
  • readCSV
• Data visualization in memory (RAM view)
• Simple command validation

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📝 Example Behavior

• When inserting into an empty table, the HeapFile allocates free blocks, and the B+ Tree assigns the first page to the buffer.
• The console shows the relation’s blocks and sectors.
• The system maintains persistence through the LOAD command.
• Data modifications are reflected correctly on disk via the buffer manager.

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📑 Policies of Operation

• Buffer Manager

  • insert → loads and pins page, writes record, marks dirty, later flushed to disk
  • delete → loads page, removes record, updates disk on flush
  • select → loads required pages for query optimization
  • where → evaluates conditions on loaded pages

• Disk Manager

  • Manages writing, deleting, and retrieving data blocks
  • Ensures efficient organization of storage
  • Keeps catalog and metadata updated

• Indexing

  • Accelerates queries via B+ Tree
  • Maintains index consistency on insert/delete operations

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📜 License

This project is released under the GNU General Public License v3.0 (GPL-3.0).

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👨‍💻 Authors

Erick Malcoaccha (Natzgun)
Educational DBMS project - UNSA, Database II Course.
Focused on systems programming and database internals.

Erik Ramos
Main collaborator in the development of core components (Buffer Manager, B+Tree, Clock, etc.).