How to Migrate MySQL to PostgreSQL: A Step-by-Step Guide

Migrating from MySQL to PostgreSQL can seem like a daunting task, but with the right approach and tools, it's a straightforward process. Whether you're looking to take advantage of PostgreSQL's advanced features, better performance, or compliance requirements, this comprehensive guide will walk you through every step of the migration process.

Why Migrate from MySQL to PostgreSQL?

Before diving into the migration process, it's important to understand why many organizations choose PostgreSQL over MySQL:

• Advanced Features: PostgreSQL offers advanced data types, full-text search, JSON support, and more sophisticated indexing options.
• Better Performance: PostgreSQL often performs better for complex queries and large datasets.
• ACID Compliance: PostgreSQL has stronger ACID compliance guarantees.
• Open Source: Fully open-source with an active community and no licensing concerns.
• Extensibility: Extensive support for custom functions, operators, and data types.

Pre-Migration Planning

Proper planning is crucial for a successful migration. Here's what you need to do before starting:

1. Assess Your Current Database

Start by analyzing your MySQL database structure:

• Document all tables, views, stored procedures, and triggers
• Identify data types that may need conversion
• List all indexes and constraints
• Note any MySQL-specific features you're using

2. Check Compatibility

MySQL and PostgreSQL have some differences in syntax and features:

• Data Types: Some MySQL data types don't have direct PostgreSQL equivalents
• Functions: Function names and syntax may differ
• Auto-increment: MySQL uses AUTO_INCREMENT, PostgreSQL uses SERIAL or sequences
• String Comparison: MySQL is case-insensitive by default, PostgreSQL is case-sensitive

3. Create a Backup

Always create a complete backup of your MySQL database before starting the migration:

mysqldump -u username -p database_name > backup.sql

Step-by-Step Migration Process

Step 1: Set Up PostgreSQL Environment

First, ensure PostgreSQL is installed and running on your target server:

# Install PostgreSQL (Ubuntu/Debian)
sudo apt-get update
sudo apt-get install postgresql postgresql-contrib

# Start PostgreSQL service
sudo systemctl start postgresql
sudo systemctl enable postgresql

# Create a new database
sudo -u postgres createdb my_database

Step 2: Export MySQL Data

Export your MySQL database structure and data:

# Export structure only
mysqldump -u username -p --no-data database_name > structure.sql

# Export data only
mysqldump -u username -p --no-create-info database_name > data.sql

# Export everything
mysqldump -u username -p database_name > full_backup.sql

Step 3: Convert Schema

Convert MySQL schema to PostgreSQL-compatible format. Key conversions include:

• AUTO_INCREMENT → SERIAL or BIGSERIAL
• DATETIME → TIMESTAMP
• TINYINT(1) → BOOLEAN
• ENGINE=InnoDB → Remove (PostgreSQL uses a single storage engine)
• UNSIGNED → Use CHECK constraints or larger integer types

Step 4: Use Migration Tools

While manual conversion is possible, using automated tools significantly reduces errors and saves time. Our platform offers:

• Automatic schema conversion
• Data type mapping
• Index and constraint preservation
• Real-time migration monitoring
• Error reporting and resolution

Step 5: Import to PostgreSQL

Once your schema is converted, import it into PostgreSQL:

# Connect to PostgreSQL
psql -U username -d my_database

# Import schema
\i converted_schema.sql

# Import data
\i converted_data.sql

Step 6: Verify Data Integrity

After migration, verify that all data was transferred correctly:

• Compare row counts between MySQL and PostgreSQL
• Check sample data for accuracy
• Verify indexes and constraints
• Test application queries
• Run data validation scripts

Step 7: Update Application Code

Update your application to work with PostgreSQL:

• Change database connection strings
• Update SQL queries for PostgreSQL syntax
• Modify stored procedures and functions
• Update ORM configurations
• Test all database operations

Common Challenges and Solutions

Challenge 1: Data Type Mismatches

Problem: Some MySQL data types don't have direct PostgreSQL equivalents.

Solution: Use appropriate PostgreSQL types:

• MySQL TINYINT(1) → PostgreSQL BOOLEAN
• MySQL DATETIME → PostgreSQL TIMESTAMP
• MySQL TEXT → PostgreSQL TEXT (same, but verify encoding)

Challenge 2: Case Sensitivity

Problem: PostgreSQL is case-sensitive for identifiers.

Solution: Use quoted identifiers or convert all identifiers to lowercase during migration.

Challenge 3: Auto-increment Differences

Problem: MySQL's AUTO_INCREMENT works differently than PostgreSQL sequences.

Solution: Use SERIAL or BIGSERIAL types, or manually create sequences.

Best Practices

• Test First: Always test the migration on a copy of your database first
• Plan Downtime: Schedule migration during low-traffic periods
• Monitor Performance: Compare query performance before and after migration
• Document Changes: Keep detailed records of all conversions and modifications
• Have a Rollback Plan: Be prepared to revert if issues arise

Post-Migration Optimization

After successful migration, optimize your PostgreSQL database:

• Run ANALYZE to update statistics
• Review and optimize indexes
• Configure PostgreSQL settings for your workload
• Set up monitoring and alerting
• Plan for regular maintenance (VACUUM, REINDEX)

Conclusion

Migrating from MySQL to PostgreSQL is a significant undertaking, but with proper planning, the right tools, and careful execution, it can be completed successfully. The key is to take it step by step, verify each stage, and test thoroughly before going live.

Our free migration platform at mysqltopostgre.com automates many of these steps, making the process faster and more reliable. Whether you choose to use our tool or migrate manually, following this guide will help ensure a smooth transition.

Remember: every database is unique, so adapt these steps to your specific needs. When in doubt, test on a non-production environment first.