Bazoola

A lightweight, file-based database implementation in Python designed for educational purposes and simple applications.

Overview

Bazoola is a minimal database system that stores data in text files with fixed-width fields. It supports basic database operations like CRUD (Create, Read, Update, Delete), schema validation, foreign key relationships, and simple querying capabilities.

Features

• File-based storage: Data is stored in human-readable text files with fixed-width fields
• Schema definition: Define table schemas with typed fields
• Primary keys: Automatic ID generation (manual ID assignment validates uniqueness but doesn't support custom sequences)
• Foreign keys: Support for relationships between tables
• Indexing: ID-based indexing for fast lookups
• Joins: Support for joining related tables
• Querying: Find records by field values, substrings, or custom conditions
• Free space management: Reuses deleted record space

Installation

Install as a package

# Install directly from GitHub
pip install git+https://github.com/ddoroshev/bazoola.git

Development setup

# Clone the repository
git clone https://github.com/ddoroshev/bazoola.git
cd bazoola

# Install dependencies using Poetry
poetry install

Quick Start

from bazoola import DB, Table, Schema, Field, PK, FK, CHAR, INT, Join

# Define table schemas
class TableAuthors(Table):
    name = "authors"
    schema = Schema([
        Field("id", PK()),
        Field("name", CHAR(20)),
    ])

class TableBooks(Table):
    name = "books"
    schema = Schema([
        Field("id", PK()),
        Field("title", CHAR(20)),
        Field("author_id", FK("authors")),
        Field("year", INT(null=True)),
    ])

# Create database instance
db = DB([TableAuthors, TableBooks])

# Insert data
author = db.insert("authors", {"name": "John Doe"})
book = db.insert("books", {
    "title": "My Book",
    "author_id": author["id"],
    "year": 2024
})

# Query with joins
book_with_author = db.find_by_id(
    "books",
    book["id"],
    joins=[Join("author_id", "author", "authors")]
)
print(book_with_author)
# Output: {'id': 1, 'title': 'My Book', 'author_id': 1, 'year': 2024, 'author': {'id': 1, 'name': 'John Doe'}}

# Close the database
db.close()

Field Types

• PK(): Primary key field (auto-incrementing integer)
• INT(null=False): Integer field
• CHAR(size, null=False): Fixed-size character field
• FK(table_name, null=False): Foreign key field

Demo Application

A full-featured task management web application is included to demonstrate Bazoola's capabilities in a real-world scenario.

# Run the demo
poetry install
poetry run python demo/app.py

Visit http://localhost:5000 to explore the demo. It showcases:

• Complex schema with 4 interconnected tables (users, projects, tasks, comments)
• Foreign key relationships and joins
• CRUD operations with web forms
• Case-insensitive search across multiple tables
• Working within Bazoola's constraints (fixed-width fields, no transactions)

See demo/ for more details.

API Reference

Database Operations

# Insert a record
row = db.insert("table_name", {"field": "value"})

# Find by ID
row = db.find_by_id("table_name", id)

# Find all records
rows = db.find_all("table_name")

# Update a record
row = db.update_by_id("table_name", id, {"field": "new_value"})

# Delete a record
db.delete_by_id("table_name", id)

# Truncate table
db.truncate("table_name", cascade=False)

Advanced Queries

from bazoola import GT, LT

# Find with conditions
rows = db.find_by_cond("books", EQ(year=2020))
rows = db.find_by_cond("books", GT(year=2020))
rows = db.find_by_cond("books", LT(year=2000))
rows = db.find_by_cond("table_name", SUBSTR(field_name="substr"))
rows = db.find_by_cond("table_name", ISUBSTR(field_name="SuBsTr"))

# Query with joins
rows = db.find_all("books", joins=[
    Join("author_id", "author", "authors")
])

# Inverse joins (one-to-many)
from bazoola import InverseJoin
author = db.find_by_id("authors", 1, joins=[
    InverseJoin("author_id", "books", "books")
])

File Structure

Bazoola creates the following files for each table:

• {table_name}.dat - Main data file
• {table_name}__seqnum.dat - Sequence number for auto-increment
• {table_name}__id.idx.dat - Primary key index
• {table_name}__free.dat - Free rownum stack for space reuse

Configuration

By default, database files are stored in a data directory. You can specify a different directory when creating the database:

# Use default 'data' directory
db = DB([TableAuthors, TableBooks])

# Use custom directory
db = DB([TableAuthors, TableBooks], base_dir="/path/to/data/directory")

Testing

# Run tests
poetry run pytest

# Run tests with coverage
poetry run pytest --cov

# Type checking
poetry run mypy .

# Linting
poetry run ruff check .

Limitations

• No multi-threading support
• No transactions or rollback support
• Limited query optimization
• Fixed-size fields only
• No SQL interface (by design)

License

This project is licensed under the MIT License - see the LICENSE file for details.