Coding Standards¶

Team coding standards for data engineering projects.

Python Standards¶

Style Guide¶

We follow PEP 8 with these additions:

Line length: 88 characters (Black default)
Imports: Use isort with Black compatibility
Type hints: Required for all public functions

Tools¶

# Install development tools
pip install black isort mypy ruff

# Format code
black src/
isort src/

# Type check
mypy src/

# Lint
ruff check src/

Function Documentation¶

Use Google-style docstrings:

def process_data(
    input_path: str,
    output_path: str,
    batch_size: int = 1000
) -> int:
    """
    Process data from input to output path.
    
    Args:
        input_path: Source data path
        output_path: Destination path
        batch_size: Number of rows per batch
        
    Returns:
        Number of rows processed
        
    Raises:
        FileNotFoundError: If input path doesn't exist
    """
    pass

SQL Standards¶

Naming Conventions¶

Object	Convention	Example
Tables	`snake_case`	`customer_orders`
Columns	`snake_case`	`order_date`
Primary Keys	`id` or `{table}_id`	`customer_id`
Foreign Keys	`{referenced_table}_id`	`customer_id`

Formatting¶

-- Use uppercase for keywords
-- Align clauses for readability
SELECT 
    c.customer_id,
    c.name,
    COUNT(o.order_id) AS order_count
FROM customers c
LEFT JOIN orders o 
    ON c.customer_id = o.customer_id
WHERE c.status = 'active'
GROUP BY c.customer_id, c.name
HAVING COUNT(o.order_id) > 0
ORDER BY order_count DESC;

Tip

Use SQLFluff for automated SQL linting.