pgslice 0.2.1

Extract PostgreSQL records with all related data via FK relationships

PgSlice

Bump only what you need

Python CLI tool for extracting PostgreSQL records with all related data via foreign key relationships.

Overview

pgslice extracts a specific database record and ALL its related records by following foreign key relationships bidirectionally. Perfect for:

• Reproducing production bugs locally with real data
• Creating partial database dumps for specific users/entities
• Testing with realistic data subsets
• Debugging issues that only occur with specific data states

Extract only what you need while maintaining referential integrity.

Features

• ✅ CLI-first design: Dumps always saved to files with visible progress (matches REPL behavior)
• ✅ Bidirectional FK traversal: Follows relationships in both directions (forward and reverse)
• ✅ Circular relationship handling: Prevents infinite loops with visited tracking
• ✅ Multiple records: Extract multiple records in one operation
• ✅ Timeframe filtering: Filter specific tables by date ranges
• ✅ PK remapping: Auto-remaps auto-generated primary keys for clean imports
• ✅ DDL generation: Optionally include CREATE DATABASE/SCHEMA/TABLE statements for self-contained dumps
• ✅ Progress bar: Visual progress indicator for dump operations
• ✅ Schema caching: SQLite-based caching for improved performance
• ✅ Type-safe: Full type hints with mypy strict mode
• ✅ Secure: SQL injection prevention, secure password handling

Installation

From PyPI (Recommended)

# Install with pipx (isolated environment, recommended)
pipx install pgslice

# Or with pip
pip install pgslice

# Or with uv
uv tool install pgslice

From Docker Hub

# Pull the image
docker pull edraobdu/pgslice:latest

# Run pgslice
docker run --rm -it \
  -v $(pwd)/dumps:/home/pgslice/.pgslice/dumps \
  -e PGPASSWORD=your_password \
  edraobdu/pgslice:latest \
  pgslice --host your.db.host --port 5432 --user your_user --database your_db

# Pin to specific version
docker pull edraobdu/pgslice:0.1.1

# Use specific platform
docker pull --platform linux/amd64 edraobdu/pgslice:latest

Connecting to Localhost Database

When your PostgreSQL database runs on your host machine, use --network host (Linux) or host.docker.internal (Mac/Windows):

# Linux: Use host networking
docker run --rm -it \
  --network host \
  -v $(pwd)/dumps:/home/pgslice/.pgslice/dumps \
  -e PGPASSWORD=your_password \
  edraobdu/pgslice:latest \
  pgslice --host localhost --database your_db --dump users --pks 42

# Mac/Windows: Use special hostname
docker run --rm -it \
  -v $(pwd)/dumps:/home/pgslice/.pgslice/dumps \
  -e PGPASSWORD=your_password \
  edraobdu/pgslice:latest \
  pgslice --host host.docker.internal --database your_db --dump users --pks 42

See DOCKER_USAGE.md for more connection options.

Docker Volume Permissions

The pgslice container runs as user pgslice (UID 1000) for security. When mounting local directories as volumes, you may encounter permission issues.

The entrypoint script automatically fixes permissions on mounted volumes. However, if you still encounter issues:

# Fix permissions on host before mounting
sudo chown -R 1000:1000 ./dumps

# Then run normally
docker run --rm -it \
  -v $(pwd)/dumps:/home/pgslice/.pgslice/dumps \
  edraobdu/pgslice:latest \
  pgslice --host your.db.host --database your_db --dump users --pks 42

Alternative: Run container as your user:

docker run --rm -it \
  -v $(pwd)/dumps:/home/pgslice/.pgslice/dumps \
  --user $(id -u):$(id -g) \
  edraobdu/pgslice:latest \
  pgslice --host your.db.host --database your_db --dump users --pks 42

For remote servers:

# Run dump on remote server
ssh user@remote-server "docker run --rm -v /tmp/dumps:/home/pgslice/.pgslice/dumps \
  edraobdu/pgslice:latest pgslice --dump users --pks 42"

# Copy file locally
scp user@remote-server:/tmp/dumps/users_42_*.sql ./

From Source (Development)

See DEVELOPMENT.md for detailed development setup instructions.

Quick Start

CLI Mode

Dumps are always saved to files with visible progress indicators (helpful for large datasets):

# Basic dump (auto-generates filename like: public_users_42_TIMESTAMP.sql)
PGPASSWORD=xxx pgslice --host localhost --database mydb --dump users --pks 42

# Multiple records
PGPASSWORD=xxx pgslice --host localhost --database mydb --dump users --pks 1,2,3

# Specify output file path
pgslice --host localhost --database mydb --dump users --pks 42 --output user_42.sql

# Dump by timeframe (instead of PKs) - filters main table by date range
pgslice --host localhost --database mydb --dump orders \
    --timeframe "created_at:2024-01-01:2024-12-31" --output orders_2024.sql

# Wide mode: follow all relationships including self-referencing FKs
# Be cautious - this can result in larger datasets
pgslice --host localhost --database mydb --dump customer --pks 42 --wide

# Keep original primary keys (no remapping)
pgslice --host localhost --database mydb --dump film --pks 1 --keep-pks

# Generate self-contained SQL with DDL statements
# Includes CREATE DATABASE/SCHEMA/TABLE statements
pgslice --host localhost --database mydb --dump film --pks 1 --create-schema

# Apply truncate filter to limit related tables by date range
pgslice --host localhost --database mydb --dump customer --pks 42 \
    --truncate "rental:rental_date:2024-01-01:2024-12-31"

# Enable debug logging (writes to stderr)
pgslice --host localhost --database mydb --dump users --pks 42 \
    --log-level DEBUG 2>debug.log

Schema Exploration

# List all tables in the schema
pgslice --host localhost --database mydb --tables

# Describe table structure and relationships
pgslice --host localhost --database mydb --describe users

SSH Remote Execution

Run pgslice on a remote server and capture output locally:

# Execute on remote server, save output locally
ssh remote.server.com "PGPASSWORD=xxx pgslice --host db.internal --database mydb \
    --dump users --pks 1 --create-schema" > local_dump.sql

# With SSH tunnel for database access
ssh -f -N -L 5433:db.internal:5432 bastion.example.com
PGPASSWORD=xxx pgslice --host localhost --port 5433 --database mydb \
    --dump users --pks 42 > user.sql

Interactive REPL

# Start interactive REPL
pgslice --host localhost --database mydb

pgslice> dump "film" 1 --output film_1.sql
pgslice> tables
pgslice> describe "film"

CLI vs REPL: Output Behavior

Understanding the difference between CLI and REPL modes:

CLI Mode (files with progress)

The CLI writes to files and shows progress bars (helpful for large datasets):

# Writes to ~/.pgslice/dumps/public_users_42_TIMESTAMP.sql
pgslice --dump users --pks 42

# Specify output file
pgslice --dump users --pks 42 --output user_42.sql

REPL Mode (same behavior)

The REPL also writes to ~/.pgslice/dumps/ by default:

# Writes to ~/.pgslice/dumps/public_users_42_TIMESTAMP.sql
pgslice> dump "users" 42

# Specify custom output path
pgslice> dump "users" 42 --output /path/to/user.sql

Both modes now behave identically - always writing to files with visible progress.

Same Operations, Different Modes

Operation	CLI	REPL
List tables	pgslice --tables	pgslice> tables
Describe table	pgslice --describe users	pgslice> describe "users"
Dump (auto-named)	pgslice --dump users --pks 42	pgslice> dump "users" 42
Dump to file	pgslice --dump users --pks 42 --output user.sql	pgslice> dump "users" 42 --output user.sql
Dump (default path)	~/.pgslice/dumps/public_users_42_TIMESTAMP.sql	~/.pgslice/dumps/public_users_42_TIMESTAMP.sql
Multiple PKs	pgslice --dump users --pks 1,2,3	pgslice> dump "users" 1,2,3
Truncate filter	pgslice --dump users --pks 42 --truncate "orders:2024-01-01:2024-12-31"	pgslice> dump "users" 42 --truncate "orders:2024-01-01:2024-12-31"
Wide mode	pgslice --dump users --pks 42 --wide	pgslice> dump "users" 42 --wide

When to Use Each Mode

Use CLI mode when:

• Piping output to other commands
• Scripting and automation
• Remote execution via SSH
• One-off dumps

Use REPL mode when:

• Exploring database schema interactively
• Running multiple dumps in a session
• You prefer persistent file output
• Testing different dump configurations

Configuration

Key environment variables (see .env.example for full reference):

Variable	Description	Default
DB_HOST	Database host	localhost
DB_PORT	Database port	5432
DB_NAME	Database name	-
DB_USER	Database user	-
DB_SCHEMA	Schema to use	public
PGPASSWORD	Database password (env var only)	-
CACHE_ENABLED	Enable schema caching	true
CACHE_TTL_HOURS	Cache time-to-live	24
LOG_LEVEL	Logging level (disabled by default unless specified)	disabled
PGSLICE_OUTPUT_DIR	Output directory	~/.pgslice/dumps

Security

• ✅ Parameterized queries: All SQL uses proper parameterization
• ✅ SQL injection prevention: Identifier validation
• ✅ Secure passwords: Never logged or stored
• ✅ Read-only enforcement: Safe for production databases

Contributing

Contributions are welcome! See DEVELOPMENT.md for comprehensive development documentation including:

• Local development setup
• Code quality standards and testing guidelines
• Version management and publishing workflow
• Architecture and design patterns

Quick start for contributors:

make setup        # One-time setup (installs dependencies, hooks)
make test         # Run all tests
git commit        # Pre-commit hooks run automatically (linting, formatting, type-checking)

For troubleshooting common development issues, see the Troubleshooting section in DEVELOPMENT.md.

License

MIT