quack-diff 0.0.1

The zero-dependency regression testing tool for modern data warehouses. DuckDB-powered data diffing across Snowflake, Postgres, and more.

quack-diff

The zero-dependency regression testing tool for modern data warehouses.

DuckDB-powered data diffing across Snowflake, Postgres, and more.

Features

• DuckDB-First Architecture: Uses DuckDB as a universal adapter for database connectivity
• Dialect-Safe Hashing: Handles NULL values and type mismatches correctly across databases
• Time-Travel Support: Compare data against historical snapshots (Snowflake, Delta Lake)
• CI/CD Ready: Exit codes for pipeline integration, environment variable configuration
• Hacker-Friendly: Rich terminal output with beautiful diff tables

Installation

pip install quack-diff

Or with uv:

uv add quack-diff

Quick Start

Basic Diff

# Compare two tables
quack-diff diff --source db1.users --target db2.users --key id

# Compare with threshold (allow up to 1% difference)
quack-diff diff --source prod.orders --target dev.orders --key order_id --threshold 0.01

Time-Travel Diff (Snowflake)

# Compare current data with 5 minutes ago
quack-diff diff \
  --source snowflake.orders \
  --target snowflake.orders \
  --source-at "5 minutes ago" \
  --key order_id

Schema Comparison

quack-diff schema --source db1.users --target db2.users

Configuration

quack-diff supports configuration via environment variables:

# Snowflake
export QUACK_DIFF_SNOWFLAKE_ACCOUNT="your-account"
export QUACK_DIFF_SNOWFLAKE_USER="your-user"
export QUACK_DIFF_SNOWFLAKE_PASSWORD="your-password"

# PostgreSQL
export QUACK_DIFF_POSTGRES_CONNECTION_STRING="postgresql://user:pass@host:5432/db"

Or via a quack-diff.yaml configuration file:

snowflake:
  account: your-account
  user: your-user
  database: your-database
  
postgres:
  connection_string: postgresql://user:pass@host:5432/db

defaults:
  threshold: 0.0

How It Works

quack-diff leverages DuckDB's extension system to connect to external databases:

1. Attach: Mount remote databases using DuckDB extensions (snowflake, postgres_scanner)
2. Hash: Generate row-level hashes using dialect-safe SQL (handles NULLs, type coercion)
3. Compare: Identify mismatches by comparing hash values
4. Report: Display results in beautiful terminal tables

Development

# Clone the repository
git clone https://github.com/matteorenoldi/quack-diff.git
cd quack-diff

# Install with dev dependencies
uv sync

# Run tests
uv run pytest

# Lint
uv run ruff check .

License

MIT License - see LICENSE for details.