codenuk_backend_mine/services/git-integration/MIGRATION_STRATEGY.md

🏗️ Enterprise Database Migration Strategy

🚨 Current Issues Identified

Critical Problems

1. No Migration State Tracking - Migrations run repeatedly causing conflicts
2. Schema Duplication - Migration 017 recreates entire schema (20KB)
3. Inconsistent Patterns - Mix of idempotent and non-idempotent operations
4. Missing Versioning - No proper version control or rollback capability
5. Conflicting Constraints - Same columns added with different FK behaviors

Impact Assessment

• High Risk: Production deployments may fail
• Data Integrity: Potential for inconsistent schema states
• Maintenance: Extremely difficult to debug and maintain
• Scalability: Cannot handle complex schema evolution

🎯 Recommended Solution Architecture

1. Migration Tracking System

-- Core tracking table
schema_migrations (
  version, filename, checksum, applied_at, 
  execution_time_ms, success, error_message
)

-- Concurrency control
migration_locks (
  locked_at, locked_by, process_id
)

2. Enterprise Migration Runner

• State Tracking: Records all migration attempts
• Checksum Validation: Prevents modified migrations from re-running
• Concurrency Control: Prevents parallel migration execution
• Error Handling: Distinguishes between fatal and idempotent errors
• Rollback Support: Tracks rollback instructions

3. Migration Naming Convention

XXX_descriptive_name.sql
├── 000_migration_tracking_system.sql    # Infrastructure
├── 001_core_tables.sql                  # Core schema
├── 002_indexes_and_constraints.sql      # Performance
├── 003_user_management.sql              # Features
└── 999_data_cleanup.sql                 # Maintenance

🔧 Implementation Plan

Phase 1: Infrastructure Setup ✅

• Create migration tracking system (000_migration_tracking_system.sql)
• Build enterprise migration runner (migrate_v2.js)
• Add conflict resolution (021_cleanup_migration_conflicts.sql)

Phase 2: Migration Cleanup (Recommended)

1. Backup Current Database
2. Run New Migration System
3. Validate Schema Consistency
4. Remove Duplicate Migrations

Phase 3: Process Improvement

1. Code Review Process for all new migrations
2. Testing Strategy with migration rollback tests
3. Documentation Standards for complex schema changes

📋 Migration Best Practices

DO ✅

• Always use IF NOT EXISTS for idempotent operations
• Include rollback instructions in comments
• Test migrations on copy of production data
• Use transactions for multi-step operations
• Document breaking changes clearly

DON'T ❌

• Never modify existing migration files
• Don't create massive "complete schema" migrations
• Avoid mixing DDL and DML in same migration
• Don't skip version numbers
• Never run migrations manually in production

🚀 Quick Start Guide

1. Initialize New System

# Run the new migration system
node src/migrations/migrate_v2.js

2. Verify Status

-- Check migration history
SELECT * FROM get_migration_history();

-- Get current version
SELECT get_current_schema_version();

3. Create New Migration

# Follow naming convention
touch 022_add_new_feature.sql

📊 Schema Health Metrics

Current State

• Tables: 41 total
• Migrations: 21 files (20 + tracking)
• Conflicts: Multiple (resolved in 021)
• Duplications: High (migration 017)

Target State

• Tracking: Full migration history
• Consistency: Zero schema conflicts
• Performance: Optimized indexes
• Maintainability: Clear migration path

🔍 Monitoring & Maintenance

Regular Checks

1. Weekly: Review failed migrations
2. Monthly: Analyze schema drift
3. Quarterly: Performance optimization review

Alerts

• Migration failures
• Long-running migrations (>5 minutes)
• Schema inconsistencies between environments

🎯 Success Criteria

• ✅ Zero migration conflicts
• ✅ Full state tracking
• ✅ Rollback capability
• ✅ Performance optimization
• ✅ Documentation compliance

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Next Steps: Run the new migration system and validate all schema objects are correctly created with proper relationships and constraints.