Appendix IV: Migration and Upgrade Guides

Overview

This chapter provides comprehensive guidance for migrating between Vektagraf versions, upgrading existing applications, and handling breaking changes. Understanding migration strategies and upgrade procedures is essential for maintaining system stability while adopting new features and improvements.

Learning Objectives

• Understand version compatibility and breaking changes
• Master step-by-step upgrade procedures with rollback options
• Learn data migration strategies and validation procedures
• Explore testing and validation of upgrades
• Understand migration automation and tooling

Prerequisites

• Understanding of Vektagraf architecture and deployment modes
• Familiarity with database backup and recovery procedures
• Knowledge of version control and deployment practices

Version Compatibility Matrix

Supported Upgrade Paths

From Version	To Version	Compatibility	Migration Required	Notes
1.0.x	1.1.x	Full	Schema Only	Minor breaking changes
1.1.x	1.2.x	Full	Configuration	Multi-tenancy added
1.2.x	1.3.x	Full	None	Backward compatible
1.0.x	1.2.x	Partial	Schema + Config	Two-step migration
1.0.x	1.3.x	Partial	Schema + Config	Multi-step migration

Breaking Changes by Version

Version 1.1.0 Breaking Changes

Schema Changes:

• System schema format updated
• New required fields in tenant configuration
• Vector field metadata structure changed

API Changes:

• VektagrafList.expand() now requires type parameter
• Vector search methods moved from database to VektagrafList
• Configuration parameter names updated

Configuration Changes:

• maxMemoryMB renamed to maxMemoryBytes
• durabilityMode replaced with syncMode
• New autoIndexing parameter added

Version 1.2.0 Breaking Changes

Multi-Tenancy:

• Multi-tenancy configuration structure completely redesigned
• New tenant limit tier system introduced
• Rate limiting configuration expanded

Security:

• New security exception types introduced
• Authentication flow updated for multi-tenant support
• Permission system restructured

Transport:

• HTTP/WebSocket client replaced with transport layer integration
• Connection string format changed
• New configuration parameters for transport layer

Version 1.3.0 Breaking Changes

Performance:

• Query optimizer interface updated
• Index management API changed
• Memory management improvements with new configuration options

Pre-Migration Assessment

Migration Readiness Checklist

class MigrationAssessment {
  static Future<MigrationReadinessReport> assessReadiness(
    String currentVersion,
    String targetVersion,
    VektagrafDatabase database,
  ) async {
    final report = MigrationReadinessReport();
    
    // Version compatibility check
    report.isCompatibleUpgrade = _isCompatibleUpgrade(currentVersion, targetVersion);
    report.migrationPath = _calculateMigrationPath(currentVersion, targetVersion);
    
    // Database health check
    report.databaseHealth = await _assessDatabaseHealth(database);
    
    // Schema compatibility
    report.schemaCompatibility = await _assessSchemaCompatibility(database, targetVersion);
    
    // Configuration compatibility
    report.configCompatibility = await _assessConfigCompatibility(database, targetVersion);
    
    // Data integrity check
    report.dataIntegrity = await _assessDataIntegrity(database);
    
    // Resource requirements
    report.resourceRequirements = _assessResourceRequirements(targetVersion);
    
    // Risk assessment
    report.riskLevel = _calculateRiskLevel(report);
    
    return report;
  }
  
  static bool _isCompatibleUpgrade(String from, String to) {
    final compatibilityMatrix = {
      '1.0': ['1.1', '1.2', '1.3'],
      '1.1': ['1.2', '1.3'],
      '1.2': ['1.3'],
      '1.3': [],
    };
    
    final fromMajorMinor = from.substring(0, 3);
    final toMajorMinor = to.substring(0, 3);
    
    return compatibilityMatrix[fromMajorMinor]?.contains(toMajorMinor) ?? false;
  }
  
  static List<String> _calculateMigrationPath(String from, String to) {
    // Calculate optimal migration path
    if (from.startsWith('1.0') && to.startsWith('1.3')) {
      return ['1.0.x', '1.1.x', '1.2.x', '1.3.x'];
    } else if (from.startsWith('1.0') && to.startsWith('1.2')) {
      return ['1.0.x', '1.1.x', '1.2.x'];
    } else {
      return [from, to];
    }
  }
  
  static Future<DatabaseHealthStatus> _assessDatabaseHealth(
    VektagrafDatabase database,
  ) async {
    try {
      // Basic connectivity
      if (!database.isOpen) {
        return DatabaseHealthStatus.connectionFailed;
      }
      
      // Basic operations
      await database.objects<TestObject>();
      
      // Transaction test
      await database.transaction((txn) async {
        return true;
      });
      
      return DatabaseHealthStatus.healthy;
    } catch (e) {
      return DatabaseHealthStatus.unhealthy;
    }
  }
  
  static Future<SchemaCompatibilityStatus> _assessSchemaCompatibility(
    VektagrafDatabase database,
    String targetVersion,
  ) async {
    try {
      // Load current schema
      final currentSchema = await _getCurrentSchema(database);
      
      // Check for breaking schema changes
      final breakingChanges = _identifyBreakingSchemaChanges(
        currentSchema,
        targetVersion,
      );
      
      if (breakingChanges.isEmpty) {
        return SchemaCompatibilityStatus.compatible;
      } else if (breakingChanges.every((change) => change.isAutoMigratable)) {
        return SchemaCompatibilityStatus.migratable;
      } else {
        return SchemaCompatibilityStatus.incompatible;
      }
    } catch (e) {
      return SchemaCompatibilityStatus.unknown;
    }
  }
}

class MigrationReadinessReport {
  bool isCompatibleUpgrade = false;
  List<String> migrationPath = [];
  DatabaseHealthStatus databaseHealth = DatabaseHealthStatus.unknown;
  SchemaCompatibilityStatus schemaCompatibility = SchemaCompatibilityStatus.unknown;
  ConfigCompatibilityStatus configCompatibility = ConfigCompatibilityStatus.unknown;
  DataIntegrityStatus dataIntegrity = DataIntegrityStatus.unknown;
  ResourceRequirements resourceRequirements = ResourceRequirements();
  MigrationRiskLevel riskLevel = MigrationRiskLevel.unknown;
  
  @override
  String toString() {
    final buffer = StringBuffer();
    buffer.writeln('Migration Readiness Report');
    buffer.writeln('========================');
    buffer.writeln('Compatible Upgrade: $isCompatibleUpgrade');
    buffer.writeln('Migration Path: ${migrationPath.join(' -> ')}');
    buffer.writeln('Database Health: ${databaseHealth.name}');
    buffer.writeln('Schema Compatibility: ${schemaCompatibility.name}');
    buffer.writeln('Config Compatibility: ${configCompatibility.name}');
    buffer.writeln('Data Integrity: ${dataIntegrity.name}');
    buffer.writeln('Risk Level: ${riskLevel.name}');
    return buffer.toString();
  }
}

enum DatabaseHealthStatus { healthy, unhealthy, connectionFailed, unknown }
enum SchemaCompatibilityStatus { compatible, migratable, incompatible, unknown }
enum ConfigCompatibilityStatus { compatible, migratable, incompatible, unknown }
enum DataIntegrityStatus { intact, issues, corrupted, unknown }
enum MigrationRiskLevel { low, medium, high, critical, unknown }

class ResourceRequirements {
  int minMemoryMB = 256;
  int minDiskSpaceMB = 1024;
  Duration estimatedDowntime = Duration(minutes: 5);
  bool requiresBackup = true;
}

class TestObject {
  final String id;
  final String name;
  
  TestObject({required this.id, required this.name});
}

Data Backup Strategy

class BackupManager {
  final VektagrafDatabase database;
  final String backupPath;
  
  BackupManager(this.database, this.backupPath);
  
  /// Creates a full backup before migration
  Future<BackupResult> createPreMigrationBackup() async {
    final timestamp = DateTime.now().toIso8601String().replaceAll(':', '-');
    final backupFile = '$backupPath/vektagraf_backup_$timestamp.vkgbak';
    
    try {
      // Create backup directory
      final backupDir = Directory(backupPath);
      if (!await backupDir.exists()) {
        await backupDir.create(recursive: true);
      }
      
      // Export database
      final exportResult = await _exportDatabase(backupFile);
      
      // Verify backup integrity
      final verificationResult = await _verifyBackup(backupFile);
      
      return BackupResult(
        success: exportResult.success && verificationResult.success,
        backupFile: backupFile,
        size: await File(backupFile).length(),
        duration: exportResult.duration + verificationResult.duration,
        checksum: verificationResult.checksum,
      );
    } catch (e) {
      return BackupResult(
        success: false,
        error: e.toString(),
      );
    }
  }
  
  /// Restores from backup if migration fails
  Future<RestoreResult> restoreFromBackup(String backupFile) async {
    try {
      // Verify backup file exists and is valid
      if (!await File(backupFile).exists()) {
        throw Exception('Backup file not found: $backupFile');
      }
      
      // Verify backup integrity
      final verificationResult = await _verifyBackup(backupFile);
      if (!verificationResult.success) {
        throw Exception('Backup file is corrupted');
      }
      
      // Close current database
      if (database.isOpen) {
        await database.close();
      }
      
      // Import from backup
      final importResult = await _importDatabase(backupFile);
      
      return RestoreResult(
        success: importResult.success,
        duration: importResult.duration,
      );
    } catch (e) {
      return RestoreResult(
        success: false,
        error: e.toString(),
      );
    }
  }
  
  Future<ExportResult> _exportDatabase(String backupFile) async {
    final stopwatch = Stopwatch()..start();
    
    try {
      // Implementation would use actual export functionality
      // For now, simulate export
      await Future.delayed(Duration(seconds: 2));
      
      stopwatch.stop();
      return ExportResult(
        success: true,
        duration: stopwatch.elapsed,
      );
    } catch (e) {
      stopwatch.stop();
      return ExportResult(
        success: false,
        duration: stopwatch.elapsed,
        error: e.toString(),
      );
    }
  }
  
  Future<VerificationResult> _verifyBackup(String backupFile) async {
    final stopwatch = Stopwatch()..start();
    
    try {
      // Calculate checksum
      final file = File(backupFile);
      final bytes = await file.readAsBytes();
      final checksum = _calculateChecksum(bytes);
      
      stopwatch.stop();
      return VerificationResult(
        success: true,
        duration: stopwatch.elapsed,
        checksum: checksum,
      );
    } catch (e) {
      stopwatch.stop();
      return VerificationResult(
        success: false,
        duration: stopwatch.elapsed,
        error: e.toString(),
      );
    }
  }
  
  Future<ImportResult> _importDatabase(String backupFile) async {
    final stopwatch = Stopwatch()..start();
    
    try {
      // Implementation would use actual import functionality
      await Future.delayed(Duration(seconds: 3));
      
      stopwatch.stop();
      return ImportResult(
        success: true,
        duration: stopwatch.elapsed,
      );
    } catch (e) {
      stopwatch.stop();
      return ImportResult(
        success: false,
        duration: stopwatch.elapsed,
        error: e.toString(),
      );
    }
  }
  
  String _calculateChecksum(List<int> bytes) {
    // Simple checksum calculation (in production, use proper hash)
    return bytes.fold<int>(0, (sum, byte) => sum + byte).toString();
  }
}

class BackupResult {
  final bool success;
  final String? backupFile;
  final int? size;
  final Duration? duration;
  final String? checksum;
  final String? error;
  
  BackupResult({
    required this.success,
    this.backupFile,
    this.size,
    this.duration,
    this.checksum,
    this.error,
  });
}

class RestoreResult {
  final bool success;
  final Duration? duration;
  final String? error;
  
  RestoreResult({
    required this.success,
    this.duration,
    this.error,
  });
}

class ExportResult {
  final bool success;
  final Duration duration;
  final String? error;
  
  ExportResult({
    required this.success,
    required this.duration,
    this.error,
  });
}

class VerificationResult {
  final bool success;
  final Duration duration;
  final String? checksum;
  final String? error;
  
  VerificationResult({
    required this.success,
    required this.duration,
    this.checksum,
    this.error,
  });
}

class ImportResult {
  final bool success;
  final Duration duration;
  final String? error;
  
  ImportResult({
    required this.success,
    required this.duration,
    this.error,
  });
}

Step-by-Step Migration Procedures

Migration from 1.0.x to 1.1.x

Phase 1: Preparation

class Migration_1_0_to_1_1 {
  final VektagrafDatabase database;
  final BackupManager backupManager;
  
  Migration_1_0_to_1_1(this.database, this.backupManager);
  
  Future<MigrationResult> execute() async {
    final migrationLog = <String>[];
    
    try {
      // Step 1: Pre-migration validation
      migrationLog.add('Starting pre-migration validation...');
      await _validatePreMigration();
      migrationLog.add('Pre-migration validation completed');
      
      // Step 2: Create backup
      migrationLog.add('Creating backup...');
      final backupResult = await backupManager.createPreMigrationBackup();
      if (!backupResult.success) {
        throw Exception('Backup failed: ${backupResult.error}');
      }
      migrationLog.add('Backup created: ${backupResult.backupFile}');
      
      // Step 3: Schema migration
      migrationLog.add('Starting schema migration...');
      await _migrateSchema();
      migrationLog.add('Schema migration completed');
      
      // Step 4: Configuration migration
      migrationLog.add('Starting configuration migration...');
      await _migrateConfiguration();
      migrationLog.add('Configuration migration completed');
      
      // Step 5: Data migration
      migrationLog.add('Starting data migration...');
      await _migrateData();
      migrationLog.add('Data migration completed');
      
      // Step 6: Post-migration validation
      migrationLog.add('Starting post-migration validation...');
      await _validatePostMigration();
      migrationLog.add('Post-migration validation completed');
      
      return MigrationResult(
        success: true,
        fromVersion: '1.0.x',
        toVersion: '1.1.x',
        duration: Duration(minutes: 10), // Estimated
        log: migrationLog,
      );
    } catch (e) {
      migrationLog.add('Migration failed: $e');
      
      // Attempt rollback
      try {
        migrationLog.add('Starting rollback...');
        await _rollback();
        migrationLog.add('Rollback completed');
      } catch (rollbackError) {
        migrationLog.add('Rollback failed: $rollbackError');
      }
      
      return MigrationResult(
        success: false,
        fromVersion: '1.0.x',
        toVersion: '1.1.x',
        error: e.toString(),
        log: migrationLog,
      );
    }
  }
  
  Future<void> _validatePreMigration() async {
    // Check database health
    if (!database.isOpen) {
      throw Exception('Database is not open');
    }
    
    // Check for required permissions
    // Check disk space
    // Validate current schema version
  }
  
  Future<void> _migrateSchema() async {
    // Update system schema format
    await _updateSystemSchemaFormat();
    
    // Add new required fields
    await _addNewRequiredFields();
    
    // Update vector field metadata
    await _updateVectorFieldMetadata();
  }
  
  Future<void> _updateSystemSchemaFormat() async {
    // Implementation for system schema format update
    await Future.delayed(Duration(seconds: 1)); // Simulate work
  }
  
  Future<void> _addNewRequiredFields() async {
    // Add new fields to tenant configuration
    await Future.delayed(Duration(seconds: 1)); // Simulate work
  }
  
  Future<void> _updateVectorFieldMetadata() async {
    // Update vector field metadata structure
    await Future.delayed(Duration(seconds: 1)); // Simulate work
  }
  
  Future<void> _migrateConfiguration() async {
    // Rename maxMemoryMB to maxMemoryBytes
    await _renameConfigurationParameter('maxMemoryMB', 'maxMemoryBytes');
    
    // Replace durabilityMode with syncMode
    await _replaceConfigurationParameter('durabilityMode', 'syncMode');
    
    // Add autoIndexing parameter
    await _addConfigurationParameter('autoIndexing', true);
  }
  
  Future<void> _renameConfigurationParameter(String oldName, String newName) async {
    // Implementation for parameter renaming
    await Future.delayed(Duration(milliseconds: 100));
  }
  
  Future<void> _replaceConfigurationParameter(String oldName, String newName) async {
    // Implementation for parameter replacement with value mapping
    await Future.delayed(Duration(milliseconds: 100));
  }
  
  Future<void> _addConfigurationParameter(String name, dynamic defaultValue) async {
    // Implementation for adding new parameter
    await Future.delayed(Duration(milliseconds: 100));
  }
  
  Future<void> _migrateData() async {
    // Update existing data to match new schema
    await _updateExistingRecords();
    
    // Migrate vector data format
    await _migrateVectorData();
  }
  
  Future<void> _updateExistingRecords() async {
    // Update records to match new schema requirements
    await Future.delayed(Duration(seconds: 2));
  }
  
  Future<void> _migrateVectorData() async {
    // Migrate vector data to new format
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _validatePostMigration() async {
    // Verify schema version
    // Test basic operations
    // Validate data integrity
    // Check configuration
  }
  
  Future<void> _rollback() async {
    // Restore from backup
    // This would be implemented based on backup strategy
    await Future.delayed(Duration(seconds: 5));
  }
}

class MigrationResult {
  final bool success;
  final String fromVersion;
  final String toVersion;
  final Duration? duration;
  final String? error;
  final List<String> log;
  
  MigrationResult({
    required this.success,
    required this.fromVersion,
    required this.toVersion,
    this.duration,
    this.error,
    this.log = const [],
  });
  
  @override
  String toString() {
    final buffer = StringBuffer();
    buffer.writeln('Migration Result: ${success ? 'SUCCESS' : 'FAILED'}');
    buffer.writeln('From: $fromVersion');
    buffer.writeln('To: $toVersion');
    if (duration != null) {
      buffer.writeln('Duration: ${duration!.inMinutes}m ${duration!.inSeconds % 60}s');
    }
    if (error != null) {
      buffer.writeln('Error: $error');
    }
    if (log.isNotEmpty) {
      buffer.writeln('Log:');
      for (final entry in log) {
        buffer.writeln('  $entry');
      }
    }
    return buffer.toString();
  }
}

Migration from 1.1.x to 1.2.x (Multi-Tenancy)

class Migration_1_1_to_1_2 {
  final VektagrafDatabase database;
  final BackupManager backupManager;
  
  Migration_1_1_to_1_2(this.database, this.backupManager);
  
  Future<MigrationResult> execute() async {
    final migrationLog = <String>[];
    
    try {
      // Step 1: Backup
      migrationLog.add('Creating backup...');
      final backupResult = await backupManager.createPreMigrationBackup();
      if (!backupResult.success) {
        throw Exception('Backup failed: ${backupResult.error}');
      }
      
      // Step 2: Multi-tenancy configuration migration
      migrationLog.add('Migrating multi-tenancy configuration...');
      await _migrateMultiTenancyConfig();
      
      // Step 3: Security system migration
      migrationLog.add('Migrating security system...');
      await _migrateSecuritySystem();
      
      // Step 4: Transport layer migration
      migrationLog.add('Migrating transport layer...');
      await _migrateTransportLayer();
      
      // Step 5: Data partitioning for multi-tenancy
      migrationLog.add('Setting up data partitioning...');
      await _setupDataPartitioning();
      
      // Step 6: Validation
      migrationLog.add('Validating migration...');
      await _validateMultiTenantMigration();
      
      return MigrationResult(
        success: true,
        fromVersion: '1.1.x',
        toVersion: '1.2.x',
        log: migrationLog,
      );
    } catch (e) {
      migrationLog.add('Migration failed: $e');
      return MigrationResult(
        success: false,
        fromVersion: '1.1.x',
        toVersion: '1.2.x',
        error: e.toString(),
        log: migrationLog,
      );
    }
  }
  
  Future<void> _migrateMultiTenancyConfig() async {
    // Convert old tenant configuration to new format
    await _convertTenantConfiguration();
    
    // Set up tenant limit tiers
    await _setupTenantLimitTiers();
    
    // Configure rate limiting
    await _configureRateLimiting();
  }
  
  Future<void> _convertTenantConfiguration() async {
    // Implementation for converting tenant configuration
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _setupTenantLimitTiers() async {
    // Set up default tenant tiers
    final defaultTiers = {
      'tier1': TenantLimitTierConfig(
        name: 'tier1',
        rateLimit: RateLimitConfig(maxRequests: 100),
        storageLimit: StorageLimitConfig(maxStorageBytes: 100 * 1024 * 1024),
        requestLimit: RequestLimitConfig(dailyLimit: 10000),
      ),
      'tier2': TenantLimitTierConfig(
        name: 'tier2',
        rateLimit: RateLimitConfig(maxRequests: 500),
        storageLimit: StorageLimitConfig(maxStorageBytes: 1024 * 1024 * 1024),
        requestLimit: RequestLimitConfig(dailyLimit: 100000),
      ),
    };
    
    // Store tier configurations
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<void> _configureRateLimiting() async {
    // Set up rate limiting infrastructure
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<void> _migrateSecuritySystem() async {
    // Update authentication flow
    await _updateAuthenticationFlow();
    
    // Migrate permission system
    await _migratePermissionSystem();
    
    // Set up new security exceptions
    await _setupSecurityExceptions();
  }
  
  Future<void> _updateAuthenticationFlow() async {
    // Update authentication for multi-tenant support
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<void> _migratePermissionSystem() async {
    // Restructure permission system
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<void> _setupSecurityExceptions() async {
    // Configure new security exception types
    await Future.delayed(Duration(milliseconds: 200));
  }
  
  Future<void> _migrateTransportLayer() async {
    // Replace HTTP/WebSocket with transport layer
    await _replaceHttpWebSocketClient();
    
    // Update connection string format
    await _updateConnectionStringFormat();
    
    // Configure transport parameters
    await _configureTransportParameters();
  }
  
  Future<void> _replaceHttpWebSocketClient() async {
    // Implementation for replacing client
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _updateConnectionStringFormat() async {
    // Convert https:// to tcp:// format
    await Future.delayed(Duration(milliseconds: 200));
  }
  
  Future<void> _configureTransportParameters() async {
    // Set up new transport configuration
    await Future.delayed(Duration(milliseconds: 300));
  }
  
  Future<void> _setupDataPartitioning() async {
    // Set up tenant data isolation
    await Future.delayed(Duration(seconds: 2));
  }
  
  Future<void> _validateMultiTenantMigration() async {
    // Validate multi-tenancy features
    await Future.delayed(Duration(seconds: 1));
  }
}

Data Migration Strategies

Schema Evolution

class SchemaEvolutionManager {
  final VektagrafDatabase database;
  
  SchemaEvolutionManager(this.database);
  
  Future<void> evolveSchema(
    VektagrafSchema oldSchema,
    VektagrafSchema newSchema,
  ) async {
    final evolution = _analyzeSchemaEvolution(oldSchema, newSchema);
    
    for (final change in evolution.changes) {
      await _applySchemaChange(change);
    }
  }
  
  SchemaEvolution _analyzeSchemaEvolution(
    VektagrafSchema oldSchema,
    VektagrafSchema newSchema,
  ) {
    final changes = <SchemaChange>[];
    
    // Detect model changes
    for (final modelName in newSchema.models.keys) {
      if (!oldSchema.models.containsKey(modelName)) {
        // New model
        changes.add(SchemaChange(
          type: SchemaChangeType.addModel,
          modelName: modelName,
          newModel: newSchema.models[modelName],
        ));
      } else {
        // Model exists, check for field changes
        final oldModel = oldSchema.models[modelName]!;
        final newModel = newSchema.models[modelName]!;
        
        changes.addAll(_analyzeModelChanges(oldModel, newModel));
      }
    }
    
    // Detect removed models
    for (final modelName in oldSchema.models.keys) {
      if (!newSchema.models.containsKey(modelName)) {
        changes.add(SchemaChange(
          type: SchemaChangeType.removeModel,
          modelName: modelName,
          oldModel: oldSchema.models[modelName],
        ));
      }
    }
    
    return SchemaEvolution(changes: changes);
  }
  
  List<SchemaChange> _analyzeModelChanges(
    ModelDefinition oldModel,
    ModelDefinition newModel,
  ) {
    final changes = <SchemaChange>[];
    
    // Detect field changes
    for (final fieldName in newModel.fields.keys) {
      if (!oldModel.fields.containsKey(fieldName)) {
        // New field
        changes.add(SchemaChange(
          type: SchemaChangeType.addField,
          modelName: newModel.name,
          fieldName: fieldName,
          newField: newModel.fields[fieldName],
        ));
      } else {
        // Field exists, check for type changes
        final oldField = oldModel.fields[fieldName]!;
        final newField = newModel.fields[fieldName]!;
        
        if (oldField.type != newField.type) {
          changes.add(SchemaChange(
            type: SchemaChangeType.changeFieldType,
            modelName: newModel.name,
            fieldName: fieldName,
            oldField: oldField,
            newField: newField,
          ));
        }
      }
    }
    
    // Detect removed fields
    for (final fieldName in oldModel.fields.keys) {
      if (!newModel.fields.containsKey(fieldName)) {
        changes.add(SchemaChange(
          type: SchemaChangeType.removeField,
          modelName: newModel.name,
          fieldName: fieldName,
          oldField: oldModel.fields[fieldName],
        ));
      }
    }
    
    return changes;
  }
  
  Future<void> _applySchemaChange(SchemaChange change) async {
    switch (change.type) {
      case SchemaChangeType.addModel:
        await _addModel(change.newModel!);
        break;
      case SchemaChangeType.removeModel:
        await _removeModel(change.oldModel!);
        break;
      case SchemaChangeType.addField:
        await _addField(change.modelName, change.newField!);
        break;
      case SchemaChangeType.removeField:
        await _removeField(change.modelName, change.fieldName!);
        break;
      case SchemaChangeType.changeFieldType:
        await _changeFieldType(
          change.modelName,
          change.fieldName!,
          change.oldField!,
          change.newField!,
        );
        break;
    }
  }
  
  Future<void> _addModel(ModelDefinition model) async {
    // Implementation for adding new model
    await Future.delayed(Duration(milliseconds: 100));
  }
  
  Future<void> _removeModel(ModelDefinition model) async {
    // Implementation for removing model (with data migration)
    await Future.delayed(Duration(milliseconds: 200));
  }
  
  Future<void> _addField(String modelName, FieldDefinition field) async {
    // Implementation for adding field with default value
    await Future.delayed(Duration(milliseconds: 50));
  }
  
  Future<void> _removeField(String modelName, String fieldName) async {
    // Implementation for removing field (with data preservation)
    await Future.delayed(Duration(milliseconds: 50));
  }
  
  Future<void> _changeFieldType(
    String modelName,
    String fieldName,
    FieldDefinition oldField,
    FieldDefinition newField,
  ) async {
    // Implementation for changing field type with data conversion
    await Future.delayed(Duration(milliseconds: 100));
  }
}

class SchemaEvolution {
  final List<SchemaChange> changes;
  
  SchemaEvolution({required this.changes});
}

class SchemaChange {
  final SchemaChangeType type;
  final String modelName;
  final String? fieldName;
  final ModelDefinition? oldModel;
  final ModelDefinition? newModel;
  final FieldDefinition? oldField;
  final FieldDefinition? newField;
  
  SchemaChange({
    required this.type,
    required this.modelName,
    this.fieldName,
    this.oldModel,
    this.newModel,
    this.oldField,
    this.newField,
  });
}

enum SchemaChangeType {
  addModel,
  removeModel,
  addField,
  removeField,
  changeFieldType,
}
```### Data Tr
ansformation

```dart
class DataTransformationEngine {
  final VektagrafDatabase database;
  
  DataTransformationEngine(this.database);
  
  Future<void> transformData(List<DataTransformation> transformations) async {
    for (final transformation in transformations) {
      await _executeTransformation(transformation);
    }
  }
  
  Future<void> _executeTransformation(DataTransformation transformation) async {
    switch (transformation.type) {
      case TransformationType.fieldRename:
        await _renameField(transformation);
        break;
      case TransformationType.fieldTypeChange:
        await _changeFieldType(transformation);
        break;
      case TransformationType.dataFormat:
        await _transformDataFormat(transformation);
        break;
      case TransformationType.vectorMigration:
        await _migrateVectorData(transformation);
        break;
    }
  }
  
  Future<void> _renameField(DataTransformation transformation) async {
    // Rename field in all existing records
    await database.transaction((txn) async {
      final objects = await txn.objects<dynamic>();
      
      for (final object in objects) {
        if (object.containsKey(transformation.oldFieldName)) {
          final value = object[transformation.oldFieldName];
          object.remove(transformation.oldFieldName);
          object[transformation.newFieldName!] = value;
          
          // Update object in database
          await txn.update(object['id'], object, object['_revision']);
        }
      }
    });
  }
  
  Future<void> _changeFieldType(DataTransformation transformation) async {
    // Convert field type in all existing records
    await database.transaction((txn) async {
      final objects = await txn.objects<dynamic>();
      
      for (final object in objects) {
        if (object.containsKey(transformation.fieldName)) {
          final oldValue = object[transformation.fieldName];
          final newValue = _convertValue(
            oldValue,
            transformation.oldType!,
            transformation.newType!,
          );
          
          object[transformation.fieldName] = newValue;
          await txn.update(object['id'], object, object['_revision']);
        }
      }
    });
  }
  
  Future<void> _transformDataFormat(DataTransformation transformation) async {
    // Apply custom data transformation
    await database.transaction((txn) async {
      final objects = await txn.objects<dynamic>();
      
      for (final object in objects) {
        final transformedObject = transformation.transformer!(object);
        await txn.update(object['id'], transformedObject, object['_revision']);
      }
    });
  }
  
  Future<void> _migrateVectorData(DataTransformation transformation) async {
    // Migrate vector data format
    await database.transaction((txn) async {
      final objects = await txn.objects<dynamic>();
      
      for (final object in objects) {
        if (object.containsKey(transformation.fieldName)) {
          final vectorData = object[transformation.fieldName];
          final migratedVector = _migrateVectorFormat(
            vectorData,
            transformation.vectorMigration!,
          );
          
          object[transformation.fieldName] = migratedVector;
          await txn.update(object['id'], object, object['_revision']);
        }
      }
    });
  }
  
  dynamic _convertValue(dynamic value, String fromType, String toType) {
    // Type conversion logic
    if (fromType == 'string' && toType == 'int32') {
      return int.tryParse(value.toString()) ?? 0;
    } else if (fromType == 'int32' && toType == 'string') {
      return value.toString();
    } else if (fromType == 'float32' && toType == 'float64') {
      return value.toDouble();
    }
    
    return value; // No conversion needed
  }
  
  Map<String, dynamic> _migrateVectorFormat(
    dynamic vectorData,
    VectorMigration migration,
  ) {
    switch (migration.type) {
      case VectorMigrationType.dimensionChange:
        return _changeDimensions(vectorData, migration);
      case VectorMigrationType.formatChange:
        return _changeFormat(vectorData, migration);
      case VectorMigrationType.metadataUpdate:
        return _updateMetadata(vectorData, migration);
    }
  }
  
  Map<String, dynamic> _changeDimensions(
    dynamic vectorData,
    VectorMigration migration,
  ) {
    final vector = List<double>.from(vectorData['vector']);
    final newDimensions = migration.newDimensions!;
    
    if (vector.length > newDimensions) {
      // Truncate vector
      return {
        ...vectorData,
        'vector': vector.take(newDimensions).toList(),
        'dimensions': newDimensions,
      };
    } else if (vector.length < newDimensions) {
      // Pad vector with zeros
      final padding = List.filled(newDimensions - vector.length, 0.0);
      return {
        ...vectorData,
        'vector': [...vector, ...padding],
        'dimensions': newDimensions,
      };
    }
    
    return vectorData; // No change needed
  }
  
  Map<String, dynamic> _changeFormat(
    dynamic vectorData,
    VectorMigration migration,
  ) {
    // Convert vector format (e.g., from array to object)
    return {
      'vector': vectorData['vector'],
      'dimensions': vectorData['vector'].length,
      'metadata': vectorData['metadata'] ?? {},
      'format_version': migration.newFormatVersion,
    };
  }
  
  Map<String, dynamic> _updateMetadata(
    dynamic vectorData,
    VectorMigration migration,
  ) {
    // Update vector metadata structure
    return {
      ...vectorData,
      'metadata': {
        ...vectorData['metadata'] ?? {},
        ...migration.metadataUpdates ?? {},
      },
    };
  }
}

class DataTransformation {
  final TransformationType type;
  final String? modelName;
  final String? fieldName;
  final String? oldFieldName;
  final String? newFieldName;
  final String? oldType;
  final String? newType;
  final Map<String, dynamic> Function(Map<String, dynamic>)? transformer;
  final VectorMigration? vectorMigration;
  
  DataTransformation({
    required this.type,
    this.modelName,
    this.fieldName,
    this.oldFieldName,
    this.newFieldName,
    this.oldType,
    this.newType,
    this.transformer,
    this.vectorMigration,
  });
}

enum TransformationType {
  fieldRename,
  fieldTypeChange,
  dataFormat,
  vectorMigration,
}

class VectorMigration {
  final VectorMigrationType type;
  final int? oldDimensions;
  final int? newDimensions;
  final String? oldFormatVersion;
  final String? newFormatVersion;
  final Map<String, dynamic>? metadataUpdates;
  
  VectorMigration({
    required this.type,
    this.oldDimensions,
    this.newDimensions,
    this.oldFormatVersion,
    this.newFormatVersion,
    this.metadataUpdates,
  });
}

enum VectorMigrationType {
  dimensionChange,
  formatChange,
  metadataUpdate,
}

Migration Testing and Validation

Automated Migration Testing

class MigrationTestSuite {
  final String testDatabasePath;
  final String backupPath;
  
  MigrationTestSuite(this.testDatabasePath, this.backupPath);
  
  Future<MigrationTestResult> runMigrationTests(
    String fromVersion,
    String toVersion,
  ) async {
    final testResults = <String, bool>{};
    final testLog = <String>[];
    
    try {
      // Test 1: Basic migration functionality
      testLog.add('Testing basic migration functionality...');
      testResults['basicMigration'] = await _testBasicMigration(fromVersion, toVersion);
      
      // Test 2: Data integrity preservation
      testLog.add('Testing data integrity preservation...');
      testResults['dataIntegrity'] = await _testDataIntegrity(fromVersion, toVersion);
      
      // Test 3: Schema compatibility
      testLog.add('Testing schema compatibility...');
      testResults['schemaCompatibility'] = await _testSchemaCompatibility(fromVersion, toVersion);
      
      // Test 4: Performance impact
      testLog.add('Testing performance impact...');
      testResults['performanceImpact'] = await _testPerformanceImpact(fromVersion, toVersion);
      
      // Test 5: Rollback functionality
      testLog.add('Testing rollback functionality...');
      testResults['rollbackFunctionality'] = await _testRollbackFunctionality(fromVersion, toVersion);
      
      // Test 6: Multi-tenant migration (if applicable)
      if (toVersion.startsWith('1.2')) {
        testLog.add('Testing multi-tenant migration...');
        testResults['multiTenantMigration'] = await _testMultiTenantMigration(fromVersion, toVersion);
      }
      
      final allTestsPassed = testResults.values.every((result) => result);
      
      return MigrationTestResult(
        success: allTestsPassed,
        fromVersion: fromVersion,
        toVersion: toVersion,
        testResults: testResults,
        log: testLog,
      );
    } catch (e) {
      testLog.add('Migration test failed: $e');
      return MigrationTestResult(
        success: false,
        fromVersion: fromVersion,
        toVersion: toVersion,
        testResults: testResults,
        log: testLog,
        error: e.toString(),
      );
    }
  }
  
  Future<bool> _testBasicMigration(String fromVersion, String toVersion) async {
    try {
      // Create test database with old version
      final database = await _createTestDatabase(fromVersion);
      
      // Populate with test data
      await _populateTestData(database);
      
      // Perform migration
      final migrationResult = await _performTestMigration(database, fromVersion, toVersion);
      
      // Verify migration success
      return migrationResult.success;
    } catch (e) {
      return false;
    }
  }
  
  Future<bool> _testDataIntegrity(String fromVersion, String toVersion) async {
    try {
      // Create test database and populate
      final database = await _createTestDatabase(fromVersion);
      final originalData = await _captureDataSnapshot(database);
      
      // Perform migration
      await _performTestMigration(database, fromVersion, toVersion);
      
      // Verify data integrity
      final migratedData = await _captureDataSnapshot(database);
      return _compareDataSnapshots(originalData, migratedData);
    } catch (e) {
      return false;
    }
  }
  
  Future<bool> _testSchemaCompatibility(String fromVersion, String toVersion) async {
    try {
      // Test schema evolution
      final database = await _createTestDatabase(fromVersion);
      await _performTestMigration(database, fromVersion, toVersion);
      
      // Verify schema is valid for new version
      return await _validateSchemaForVersion(database, toVersion);
    } catch (e) {
      return false;
    }
  }
  
  Future<bool> _testPerformanceImpact(String fromVersion, String toVersion) async {
    try {
      // Measure performance before migration
      final database = await _createTestDatabase(fromVersion);
      await _populateTestData(database);
      final beforePerformance = await _measurePerformance(database);
      
      // Perform migration
      await _performTestMigration(database, fromVersion, toVersion);
      
      // Measure performance after migration
      final afterPerformance = await _measurePerformance(database);
      
      // Verify performance hasn't degraded significantly
      return _comparePerformance(beforePerformance, afterPerformance);
    } catch (e) {
      return false;
    }
  }
  
  Future<bool> _testRollbackFunctionality(String fromVersion, String toVersion) async {
    try {
      // Create test database and backup
      final database = await _createTestDatabase(fromVersion);
      final originalData = await _captureDataSnapshot(database);
      
      final backupManager = BackupManager(database, backupPath);
      final backupResult = await backupManager.createPreMigrationBackup();
      
      if (!backupResult.success) return false;
      
      // Perform migration
      await _performTestMigration(database, fromVersion, toVersion);
      
      // Perform rollback
      final restoreResult = await backupManager.restoreFromBackup(backupResult.backupFile!);
      
      if (!restoreResult.success) return false;
      
      // Verify data is restored correctly
      final restoredData = await _captureDataSnapshot(database);
      return _compareDataSnapshots(originalData, restoredData);
    } catch (e) {
      return false;
    }
  }
  
  Future<bool> _testMultiTenantMigration(String fromVersion, String toVersion) async {
    try {
      // Create test database with multi-tenant data
      final database = await _createTestDatabase(fromVersion);
      await _populateMultiTenantTestData(database);
      
      // Perform migration
      await _performTestMigration(database, fromVersion, toVersion);
      
      // Verify multi-tenant features work
      return await _validateMultiTenantFeatures(database);
    } catch (e) {
      return false;
    }
  }
  
  Future<VektagrafDatabase> _createTestDatabase(String version) async {
    // Implementation would create database with specific version
    final database = VektagrafDatabaseImpl();
    await database.open(testDatabasePath);
    return database;
  }
  
  Future<void> _populateTestData(VektagrafDatabase database) async {
    // Populate with representative test data
    await database.transaction((txn) async {
      for (int i = 0; i < 100; i++) {
        await txn.save({
          'id': 'test_$i',
          'name': 'Test Object $i',
          'value': i,
          'vector': List.generate(128, (index) => index.toDouble()),
        });
      }
    });
  }
  
  Future<void> _populateMultiTenantTestData(VektagrafDatabase database) async {
    // Populate with multi-tenant test data
    await database.transaction((txn) async {
      for (int tenantId = 1; tenantId <= 3; tenantId++) {
        for (int i = 0; i < 50; i++) {
          await txn.save({
            'id': 'tenant_${tenantId}_object_$i',
            'tenantId': 'tenant_$tenantId',
            'name': 'Tenant $tenantId Object $i',
            'value': i,
          });
        }
      }
    });
  }
  
  Future<MigrationResult> _performTestMigration(
    VektagrafDatabase database,
    String fromVersion,
    String toVersion,
  ) async {
    // Perform actual migration based on version
    if (fromVersion.startsWith('1.0') && toVersion.startsWith('1.1')) {
      final migration = Migration_1_0_to_1_1(database, BackupManager(database, backupPath));
      return await migration.execute();
    } else if (fromVersion.startsWith('1.1') && toVersion.startsWith('1.2')) {
      final migration = Migration_1_1_to_1_2(database, BackupManager(database, backupPath));
      return await migration.execute();
    }
    
    throw Exception('Unsupported migration path: $fromVersion -> $toVersion');
  }
  
  Future<DataSnapshot> _captureDataSnapshot(VektagrafDatabase database) async {
    // Capture current state of database
    final objects = await database.objects<dynamic>();
    return DataSnapshot(
      objectCount: objects.length,
      checksum: _calculateDataChecksum(objects),
      sampleData: objects.take(10).toList(),
    );
  }
  
  bool _compareDataSnapshots(DataSnapshot before, DataSnapshot after) {
    // Compare data snapshots for integrity
    return before.objectCount == after.objectCount &&
           before.checksum == after.checksum;
  }
  
  Future<bool> _validateSchemaForVersion(VektagrafDatabase database, String version) async {
    // Validate schema matches expected version
    try {
      // This would check schema version and structure
      return true;
    } catch (e) {
      return false;
    }
  }
  
  Future<PerformanceMetrics> _measurePerformance(VektagrafDatabase database) async {
    final stopwatch = Stopwatch();
    
    // Measure read performance
    stopwatch.start();
    await database.objects<dynamic>();
    stopwatch.stop();
    final readTime = stopwatch.elapsedMilliseconds;
    
    // Measure write performance
    stopwatch.reset();
    stopwatch.start();
    await database.transaction((txn) async {
      await txn.save({'id': 'perf_test', 'data': 'test'});
    });
    stopwatch.stop();
    final writeTime = stopwatch.elapsedMilliseconds;
    
    return PerformanceMetrics(
      readTimeMs: readTime,
      writeTimeMs: writeTime,
    );
  }
  
  bool _comparePerformance(PerformanceMetrics before, PerformanceMetrics after) {
    // Allow up to 20% performance degradation
    const maxDegradation = 1.2;
    
    return after.readTimeMs <= before.readTimeMs * maxDegradation &&
           after.writeTimeMs <= before.writeTimeMs * maxDegradation;
  }
  
  Future<bool> _validateMultiTenantFeatures(VektagrafDatabase database) async {
    try {
      // Test multi-tenant functionality
      // This would test tenant isolation, limits, etc.
      return true;
    } catch (e) {
      return false;
    }
  }
  
  String _calculateDataChecksum(List<dynamic> objects) {
    // Simple checksum calculation
    return objects.fold<int>(0, (sum, obj) => sum + obj.hashCode).toString();
  }
}

class MigrationTestResult {
  final bool success;
  final String fromVersion;
  final String toVersion;
  final Map<String, bool> testResults;
  final List<String> log;
  final String? error;
  
  MigrationTestResult({
    required this.success,
    required this.fromVersion,
    required this.toVersion,
    required this.testResults,
    required this.log,
    this.error,
  });
  
  @override
  String toString() {
    final buffer = StringBuffer();
    buffer.writeln('Migration Test Result: ${success ? 'PASSED' : 'FAILED'}');
    buffer.writeln('Migration: $fromVersion -> $toVersion');
    buffer.writeln('Test Results:');
    
    for (final entry in testResults.entries) {
      final status = entry.value ? 'PASS' : 'FAIL';
      buffer.writeln('  ${entry.key}: $status');
    }
    
    if (error != null) {
      buffer.writeln('Error: $error');
    }
    
    return buffer.toString();
  }
}

class DataSnapshot {
  final int objectCount;
  final String checksum;
  final List<dynamic> sampleData;
  
  DataSnapshot({
    required this.objectCount,
    required this.checksum,
    required this.sampleData,
  });
}

class PerformanceMetrics {
  final int readTimeMs;
  final int writeTimeMs;
  
  PerformanceMetrics({
    required this.readTimeMs,
    required this.writeTimeMs,
  });
}

Rollback Procedures

Automated Rollback

class RollbackManager {
  final VektagrafDatabase database;
  final BackupManager backupManager;
  final String rollbackLogPath;
  
  RollbackManager(this.database, this.backupManager, this.rollbackLogPath);
  
  Future<RollbackResult> performRollback(String backupFile) async {
    final rollbackLog = <String>[];
    
    try {
      rollbackLog.add('Starting rollback process...');
      
      // Step 1: Validate backup file
      rollbackLog.add('Validating backup file...');
      if (!await _validateBackupFile(backupFile)) {
        throw Exception('Backup file validation failed');
      }
      
      // Step 2: Stop all database operations
      rollbackLog.add('Stopping database operations...');
      await _stopDatabaseOperations();
      
      // Step 3: Create current state backup (for safety)
      rollbackLog.add('Creating safety backup of current state...');
      final safetyBackup = await backupManager.createPreMigrationBackup();
      if (!safetyBackup.success) {
        throw Exception('Failed to create safety backup');
      }
      
      // Step 4: Restore from backup
      rollbackLog.add('Restoring from backup...');
      final restoreResult = await backupManager.restoreFromBackup(backupFile);
      if (!restoreResult.success) {
        throw Exception('Restore operation failed: ${restoreResult.error}');
      }
      
      // Step 5: Validate restored state
      rollbackLog.add('Validating restored state...');
      await _validateRestoredState();
      
      // Step 6: Resume database operations
      rollbackLog.add('Resuming database operations...');
      await _resumeDatabaseOperations();
      
      rollbackLog.add('Rollback completed successfully');
      
      return RollbackResult(
        success: true,
        backupFile: backupFile,
        safetyBackupFile: safetyBackup.backupFile,
        log: rollbackLog,
      );
    } catch (e) {
      rollbackLog.add('Rollback failed: $e');
      
      return RollbackResult(
        success: false,
        backupFile: backupFile,
        error: e.toString(),
        log: rollbackLog,
      );
    }
  }
  
  Future<bool> _validateBackupFile(String backupFile) async {
    final file = File(backupFile);
    if (!await file.exists()) {
      return false;
    }
    
    // Verify backup integrity
    try {
      final verificationResult = await backupManager._verifyBackup(backupFile);
      return verificationResult.success;
    } catch (e) {
      return false;
    }
  }
  
  Future<void> _stopDatabaseOperations() async {
    // Implementation would gracefully stop all operations
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _resumeDatabaseOperations() async {
    // Implementation would resume normal operations
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _validateRestoredState() async {
    // Validate that the restored database is functional
    try {
      if (!database.isOpen) {
        await database.open(database.path);
      }
      
      // Test basic operations
      await database.objects<dynamic>();
      
      // Test transactions
      await database.transaction((txn) async {
        return true;
      });
    } catch (e) {
      throw Exception('Restored database validation failed: $e');
    }
  }
}

class RollbackResult {
  final bool success;
  final String backupFile;
  final String? safetyBackupFile;
  final String? error;
  final List<String> log;
  
  RollbackResult({
    required this.success,
    required this.backupFile,
    this.safetyBackupFile,
    this.error,
    required this.log,
  });
  
  @override
  String toString() {
    final buffer = StringBuffer();
    buffer.writeln('Rollback Result: ${success ? 'SUCCESS' : 'FAILED'}');
    buffer.writeln('Backup File: $backupFile');
    if (safetyBackupFile != null) {
      buffer.writeln('Safety Backup: $safetyBackupFile');
    }
    if (error != null) {
      buffer.writeln('Error: $error');
    }
    buffer.writeln('Log:');
    for (final entry in log) {
      buffer.writeln('  $entry');
    }
    return buffer.toString();
  }
}

Migration Automation

CI/CD Integration

class MigrationPipeline {
  final String environment;
  final Map<String, dynamic> config;
  
  MigrationPipeline(this.environment, this.config);
  
  Future<PipelineResult> executeMigrationPipeline(
    String fromVersion,
    String toVersion,
  ) async {
    final pipelineLog = <String>[];
    
    try {
      // Stage 1: Pre-migration checks
      pipelineLog.add('Stage 1: Pre-migration checks');
      await _preMigrationChecks(fromVersion, toVersion);
      
      // Stage 2: Backup creation
      pipelineLog.add('Stage 2: Creating backups');
      final backupResult = await _createBackups();
      
      // Stage 3: Migration testing (in staging)
      if (environment != 'production') {
        pipelineLog.add('Stage 3: Migration testing');
        await _runMigrationTests(fromVersion, toVersion);
      }
      
      // Stage 4: Production migration
      pipelineLog.add('Stage 4: Production migration');
      final migrationResult = await _executeMigration(fromVersion, toVersion);
      
      // Stage 5: Post-migration validation
      pipelineLog.add('Stage 5: Post-migration validation');
      await _postMigrationValidation();
      
      // Stage 6: Monitoring setup
      pipelineLog.add('Stage 6: Setting up monitoring');
      await _setupPostMigrationMonitoring();
      
      return PipelineResult(
        success: true,
        fromVersion: fromVersion,
        toVersion: toVersion,
        environment: environment,
        log: pipelineLog,
      );
    } catch (e) {
      pipelineLog.add('Pipeline failed: $e');
      
      // Attempt automatic rollback if configured
      if (config['autoRollback'] == true) {
        pipelineLog.add('Attempting automatic rollback...');
        try {
          await _performAutomaticRollback();
          pipelineLog.add('Automatic rollback completed');
        } catch (rollbackError) {
          pipelineLog.add('Automatic rollback failed: $rollbackError');
        }
      }
      
      return PipelineResult(
        success: false,
        fromVersion: fromVersion,
        toVersion: toVersion,
        environment: environment,
        error: e.toString(),
        log: pipelineLog,
      );
    }
  }
  
  Future<void> _preMigrationChecks(String fromVersion, String toVersion) async {
    // Check system resources
    await _checkSystemResources();
    
    // Validate migration path
    await _validateMigrationPath(fromVersion, toVersion);
    
    // Check database health
    await _checkDatabaseHealth();
    
    // Verify permissions
    await _verifyPermissions();
  }
  
  Future<void> _checkSystemResources() async {
    // Check available disk space, memory, etc.
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _validateMigrationPath(String fromVersion, String toVersion) async {
    // Validate that migration path is supported
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<void> _checkDatabaseHealth() async {
    // Perform database health check
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _verifyPermissions() async {
    // Verify necessary permissions for migration
    await Future.delayed(Duration(milliseconds: 500));
  }
  
  Future<BackupResult> _createBackups() async {
    // Create comprehensive backups
    await Future.delayed(Duration(seconds: 5));
    return BackupResult(success: true);
  }
  
  Future<void> _runMigrationTests(String fromVersion, String toVersion) async {
    // Run automated migration tests
    final testSuite = MigrationTestSuite('test_db_path', 'test_backup_path');
    final testResult = await testSuite.runMigrationTests(fromVersion, toVersion);
    
    if (!testResult.success) {
      throw Exception('Migration tests failed: ${testResult.error}');
    }
  }
  
  Future<MigrationResult> _executeMigration(String fromVersion, String toVersion) async {
    // Execute the actual migration
    await Future.delayed(Duration(seconds: 10));
    return MigrationResult(
      success: true,
      fromVersion: fromVersion,
      toVersion: toVersion,
    );
  }
  
  Future<void> _postMigrationValidation() async {
    // Validate migration success
    await Future.delayed(Duration(seconds: 2));
  }
  
  Future<void> _setupPostMigrationMonitoring() async {
    // Set up monitoring for post-migration period
    await Future.delayed(Duration(seconds: 1));
  }
  
  Future<void> _performAutomaticRollback() async {
    // Perform automatic rollback
    await Future.delayed(Duration(seconds: 5));
  }
}

class PipelineResult {
  final bool success;
  final String fromVersion;
  final String toVersion;
  final String environment;
  final String? error;
  final List<String> log;
  
  PipelineResult({
    required this.success,
    required this.fromVersion,
    required this.toVersion,
    required this.environment,
    this.error,
    required this.log,
  });
}

Best Practices and Recommendations

Migration Planning

1. Always Test First

   // Test migration in staging environment
   final testResult = await migrationTestSuite.runMigrationTests('1.0.5', '1.1.0');
   if (!testResult.success) {
     throw Exception('Migration tests failed, aborting production migration');
   }
   

2. Create Comprehensive Backups

   // Multiple backup strategies
   final backupStrategies = [
     FullDatabaseBackup(),
     IncrementalBackup(),
     SchemaOnlyBackup(),
     DataOnlyBackup(),
   ];
   
   for (final strategy in backupStrategies) {
     await strategy.createBackup();
   }
   

3. Plan for Rollback

   // Always have a rollback plan
   final rollbackPlan = RollbackPlan(
     backupFile: backupResult.backupFile,
     estimatedRollbackTime: Duration(minutes: 15),
     rollbackTriggers: [
       'Error rate > 5%',
       'Response time > 2x baseline',
       'Data corruption detected',
     ],
   );
   

4. Monitor During Migration

   // Set up monitoring during migration
   final migrationMonitor = MigrationMonitor();
   migrationMonitor.startMonitoring();
   
   try {
     await performMigration();
   } finally {
     migrationMonitor.stopMonitoring();
     final report = migrationMonitor.generateReport();
     print(report);
   }
   

Performance Considerations

1. Minimize Downtime

   // Use online migration techniques where possible
   final onlineMigration = OnlineMigrationStrategy();
   if (onlineMigration.isSupported(fromVersion, toVersion)) {
     await onlineMigration.execute();
   } else {
     // Fall back to offline migration
     await offlineMigration.execute();
   }
   

2. Batch Processing

   // Process data in batches to avoid memory issues
   const batchSize = 1000;
   final totalRecords = await getTotalRecordCount();
   
   for (int offset = 0; offset < totalRecords; offset += batchSize) {
     await migrateBatch(offset, batchSize);
   
     // Allow other operations to proceed
     await Future.delayed(Duration(milliseconds: 100));
   }
   

3. Resource Management

   // Monitor and manage resources during migration
   final resourceMonitor = ResourceMonitor();
   
   while (migrationInProgress) {
     final usage = resourceMonitor.getCurrentUsage();
   
     if (usage.memoryPercent > 80) {
       await pauseMigration();
       await waitForResourcesAvailable();
       await resumeMigration();
     }
   
     await Future.delayed(Duration(seconds: 10));
   }
   

Summary

This chapter provided comprehensive guidance for Vektagraf migrations and upgrades:

• Version Compatibility: Understanding breaking changes and upgrade paths
• Migration Assessment: Tools for evaluating migration readiness
• Step-by-Step Procedures: Detailed migration processes for each version
• Data Migration: Schema evolution and data transformation strategies
• Testing and Validation: Comprehensive testing frameworks for migrations
• Rollback Procedures: Automated rollback and recovery mechanisms
• Migration Automation: CI/CD integration and pipeline automation
• Best Practices: Performance optimization and risk mitigation strategies

Use this guide to plan and execute safe, reliable migrations while minimizing downtime and risk. The comprehensive testing and rollback procedures ensure that you can confidently upgrade your Vektagraf applications.

Next Steps

• Appendix I: Complete API Reference - Detailed API documentation
• Appendix II: Configuration Reference - Comprehensive configuration options
• Appendix III: Error Codes and Troubleshooting - Error handling and diagnostics
• Part I: Foundations - Core concepts and getting started
• Part V: Enterprise Deployment - Production deployment patterns