Multi-Database FRD Implementation

📋 Overview

This issue tracks the technical implementation of the Multi-Database Functional Requirements Document (FRD), focusing on the plugin architecture and engine-specific implementations for PostgreSQL, MySQL, and SQLite databases.

📚 Related Documentation

• FRD: frontend/mekong/.specs/apps/sql-editor/multi-database-frd.md
• PRD: frontend/mekong/.specs/apps/sql-editor/prd.md (updated)
• Parent Issue: #45 - Multi-Database Support

🏗️ Technical Architecture

Database Engine Plugin System

interface DatabaseEnginePlugin {
  engine: DatabaseEngine
  connectionManager: ConnectionManager
  queryExecutor: QueryExecutor
  schemaProvider: SchemaProvider
  sqlLanguageService: SQLLanguageService
  resultProcessor: ResultProcessor
  metadataExtractor: MetadataExtractor
}

File Structure

src/apps/sql-editor/
├── engines/                    # Database engine implementations
│   ├── postgresql/            # PostgreSQL engine
│   │   ├── PostgreSQLEngine.ts
│   │   ├── PostgresConnectionManager.ts
│   │   ├── PostgresQueryExecutor.ts
│   │   ├── PostgresSchemaProvider.ts
│   │   └── PostgresLanguageService.ts
│   ├── mysql/                 # MySQL engine
│   │   ├── MySQLEngine.ts
│   │   ├── MySQLConnectionManager.ts
│   │   ├── MySQLQueryExecutor.ts
│   │   ├── MySQLSchemaProvider.ts
│   │   └── MySQLLanguageService.ts
│   ├── sqlite/                # SQLite engine
│   │   ├── SQLiteEngine.ts
│   │   ├── SQLiteConnectionManager.ts
│   │   ├── SQLiteQueryExecutor.ts
│   │   ├── SQLiteSchemaProvider.ts
│   │   └── SQLiteLanguageService.ts
│   └── base/                  # Base classes and interfaces
│       ├── BaseEngine.ts
│       ├── BaseConnectionManager.ts
│       ├── BaseQueryExecutor.ts
│       ├── BaseSchemaProvider.ts
│       └── BaseLanguageService.ts
├── services/                  # Core services
│   ├── DatabaseEngineRegistry.ts
│   ├── ConnectionPoolManager.ts
│   └── QueryTranslationService.ts
└── components/               # UI components
    ├── connection/           # Connection management
    ├── schema/              # Schema browser
    └── execution/           # Query execution

🚀 Implementation Tasks

Phase 1: Foundation (Weeks 1-2)

F1. Database Engine Registry

• F1.1 Create DatabaseEngineRegistry.ts service
• F1.2 Implement engine registration system
• F1.3 Add engine capability validation
• F1.4 Create engine factory pattern
• F1.5 Add comprehensive unit tests

F2. Base Classes and Interfaces

• F2.1 Create BaseEngine.ts abstract class
• F2.2 Implement BaseConnectionManager.ts
• F2.3 Create BaseQueryExecutor.ts
• F2.4 Build BaseSchemaProvider.ts
• F2.5 Develop BaseLanguageService.ts
• F2.6 Add TypeScript interfaces for all components

Phase 2: PostgreSQL Engine (Weeks 3-4)

F3. PostgreSQL Implementation

• F3.1 Create PostgreSQLEngine.ts plugin
• F3.2 Implement PostgresConnectionManager.ts with pg library
• F3.3 Build PostgresQueryExecutor.ts with prepared statements
• F3.4 Create PostgresSchemaProvider.ts with information_schema queries
• F3.5 Develop PostgresLanguageService.ts with syntax highlighting
• F3.6 Add PostgreSQL-specific features (JSON, arrays, custom types)
• F3.7 Implement SSL connection support
• F3.8 Add comprehensive integration tests

Phase 3: MySQL Engine (Weeks 5-6)

F4. MySQL Implementation

• F4.1 Create MySQLEngine.ts plugin
• F4.2 Implement MySQLConnectionManager.ts with mysql2 library
• F4.3 Build MySQLQueryExecutor.ts with prepared statements
• F4.4 Create MySQLSchemaProvider.ts with information_schema queries
• F4.5 Develop MySQLLanguageService.ts with syntax highlighting
• F4.6 Add MySQL 8.0+ features (CTE, window functions, JSON)
• F4.7 Implement SSL connection support
• F4.8 Add comprehensive integration tests

Phase 4: SQLite Engine (Weeks 7-8)

F5. SQLite Implementation

• F5.1 Create SQLiteEngine.ts plugin
• F5.2 Implement SQLiteConnectionManager.ts with better-sqlite3 library
• F5.3 Build SQLiteQueryExecutor.ts with prepared statements
• F5.4 Create SQLiteSchemaProvider.ts with sqlite_master queries
• F5.5 Develop SQLiteLanguageService.ts with syntax highlighting
• F5.6 Add SQLite-specific features (virtual tables, FTS)
• F5.7 Support both file-based and in-memory databases
• F5.8 Add comprehensive integration tests

Phase 5: Unified Services (Weeks 9-10)

F6. Connection Pool Management

• F6.1 Create ConnectionPoolManager.ts service
• F6.2 Implement engine-specific pooling strategies
• F6.3 Add connection health monitoring
• F6.4 Create connection lifecycle management
• F6.5 Add performance metrics and monitoring

F7. Query Translation Service

• F7.1 Create QueryTranslationService.ts service
• F7.2 Implement cross-engine query translation
• F7.3 Add translation rule engine
• F7.4 Create query parser and AST generation
• F7.5 Add translation confidence scoring

F8. UI Components

• F8.1 Create DynamicConnectionForm.tsx component
• F8.2 Implement MultiEngineSchemaBrowser.tsx component
• F8.3 Build ConnectionTest.tsx component
• F8.4 Create QueryGenerator.tsx component
• F8.5 Add engine-specific form validation

🧪 Testing Requirements

Unit Testing

• T1.1 Each engine class has 90%+ test coverage
• T1.2 All service classes have comprehensive unit tests
• T1.3 Mock implementations for external dependencies
• T1.4 Error handling and edge case testing

Integration Testing

• T2.1 Real database connection testing
• T2.2 Cross-engine query execution testing
• T2.3 Schema browser functionality testing
• T2.4 Connection pool management testing

Performance Testing

• T3.1 Connection pool performance under load
• T3.2 Query execution performance across engines
• T3.3 Schema loading performance for large databases
• T3.4 Memory usage and cleanup testing

📋 Acceptance Criteria

Must-Have Features (P0)

• All three database engines (PostgreSQL, MySQL, SQLite) are fully functional
• Plugin architecture allows easy addition of new engines
• Connection management works across all engines
• Schema browser displays engine-specific metadata
• Query execution works for basic SELECT statements
• Engine-specific syntax highlighting and autocomplete

Should-Have Features (P1)

• Query translation between different SQL dialects
• Connection pooling and performance optimization
• Advanced error handling and user feedback
• Dynamic UI components that adapt to engine selection
• Comprehensive test coverage (80%+)

Could-Have Features (P2)

• Real-time connection monitoring
• Advanced query optimization recommendations
• Custom database engine plugin development tools
• Performance analytics and reporting

🔧 Technical Dependencies

Required Libraries

{
  "pg": "^8.11.0",
  "mysql2": "^3.6.0",
  "better-sqlite3": "^8.7.0",
  "@types/pg": "^8.10.0",
  "@types/mysql2": "^3.0.0"
}

Development Dependencies

{
  "@types/jest": "^29.5.0",
  "jest": "^29.5.0",
  "supertest": "^6.3.0",
  "testcontainers": "^9.0.0"
}

📅 Timeline

• Phase 1 (Weeks 1-2): Foundation and base classes
• Phase 2 (Weeks 3-4): PostgreSQL engine implementation
• Phase 3 (Weeks 5-6): MySQL engine implementation
• Phase 4 (Weeks 7-8): SQLite engine implementation
• Phase 5 (Weeks 9-10): Unified services and UI components

🎯 Success Metrics

• All three database engines are fully functional
• Plugin architecture is extensible and well-documented
• Code coverage is above 80% for all implementations
• Performance meets or exceeds single-engine implementation
• User experience is consistent across all database types
• Documentation is complete and up-to-date

🏷️ Labels

• enhancement
• sql-editor
• multi-database
• plugin-architecture
• postgresql
• mysql
• sqlite
• typescript
• implementation

👥 Assignees

• @v2kk (Primary developer)
• @Copilot (AI assistance)

This issue focuses on the technical implementation of the Multi-Database FRD, providing a detailed roadmap for building the plugin architecture and engine-specific implementations.