I'm responsible for database operations for a high-traffic web application, and we're struggling with database migrations during deployments. Our current process causes downtime or performance degradation whenever we need to modify the database schema.
Current challenges:
1. **Adding new columns** to large tables locks the table
2. **Changing indexes** causes query performance issues
3. **Data migrations** for schema changes risk data loss
4. **Rollback procedures** are complex and error-prone
Here's an example of a problematic migration:
```sql
-- Adding a NOT NULL column to a table with 10M+ rows
ALTER TABLE users ADD COLUMN phone_number VARCHAR(20) NOT NULL;
-- This locks the table for minutes/hours
```
I'm looking for database troubleshooting strategies and best practices for zero-downtime migrations. My questions:
1. What are the patterns for safe schema changes on production databases?
2. How do I handle data migrations for large tables without downtime?
3. What tools or frameworks help with database migration management?
4. How do I test migrations safely before applying to production?
This is advanced database troubleshooting territory. I need strategies that work with:
- PostgreSQL and MySQL
- Tables with millions of rows
- 24/7 application availability requirements
- Multiple application instances
I'd appreciate any code review and feedback on migration strategies or recommendations for tools that make this process safer. This feels like one of those web development support areas where experience with production systems really matters.
Also, if anyone has horror stories or success stories about database migrations, I'd love to learn from both!
Current challenges:
1. **Adding new columns** to large tables locks the table
2. **Changing indexes** causes query performance issues
3. **Data migrations** for schema changes risk data loss
4. **Rollback procedures** are complex and error-prone
Here's an example of a problematic migration:
```sql
-- Adding a NOT NULL column to a table with 10M+ rows
ALTER TABLE users ADD COLUMN phone_number VARCHAR(20) NOT NULL;
-- This locks the table for minutes/hours
```
I'm looking for database troubleshooting strategies and best practices for zero-downtime migrations. My questions:
1. What are the patterns for safe schema changes on production databases?
2. How do I handle data migrations for large tables without downtime?
3. What tools or frameworks help with database migration management?
4. How do I test migrations safely before applying to production?
This is advanced database troubleshooting territory. I need strategies that work with:
- PostgreSQL and MySQL
- Tables with millions of rows
- 24/7 application availability requirements
- Multiple application instances
I'd appreciate any code review and feedback on migration strategies or recommendations for tools that make this process safer. This feels like one of those web development support areas where experience with production systems really matters.
Also, if anyone has horror stories or success stories about database migrations, I'd love to learn from both!
