Local Database Seçenekleri

Mobil uygulamalarda lokal veri saklama, performans, offline çalışabilirlik ve kullanıcı deneyimi açısından kritik öneme sahiptir. Bu bölümde SQL tabanlı çözümlerden NoSQL alternatiflerine, key-value store'lardan objektif veritabanlarına kadar tüm lokal persistence seçenekleri detaylı olarak incelenmektedir.

SQL Tabanlı Çözümler

SQLite/Room (Android)

Room, Android'de SQLite üzerinde bir ORM katmanı sunan, compile-time verification ve type safety sağlayan modern bir database abstraction'dır.

Temel Bileşenler

@Entity Annotations

• Primary key tanımları ve auto-increment özelliği
• Foreign key ilişkileri ve referential integrity
• Index tanımları ve composite index'ler
• Özel tablo isimleri ve sütun konfigürasyonları

@Dao (Data Access Object)

• SQL sorguları ve parametrik query'ler
• @Insert, @Update, @Delete annotations
• @Query ile custom SQL sorguları
• LiveData/Flow ile reactive programming

@Database Configuration

• Room database versioning
• Entity listesi ve type converter'lar
• Migration stratejileri
• In-memory ve file-based database seçenekleri

Gelişmiş Özellikler

Migration Strategies

// Room migration örneği
val MIGRATION_1_2 = object : Migration(1, 2) {
    override fun migrate(database: SupportSQLiteDatabase) {
        database.execSQL("ALTER TABLE User ADD COLUMN age INTEGER DEFAULT 0 NOT NULL")
    }
}

Reactive Queries

• LiveData ile UI reactive güncellemeleri
• Kotlin Flow ile asenkron data stream'leri
• RxJava integration
• Coroutines support

Performance Optimizations

• WAL (Write-Ahead Logging) mode
• Prepared statements ve statement caching
• Batch operations ve bulk insert/update
• Connection pooling
• Index optimization

SQLite Cross-Platform Implementations

Flutter - sqflite & drift

sqflite: Flutter'ın native SQLite plugin'i

• Platform channel üzerinden native SQLite erişimi
• Transaction support ve batch operations
• Database versioning ve migration
• Custom SQL ve raw query desteği

drift (eski adı moor): Type-safe SQL generation

• Dart ile SQL schema tanımları
• Compile-time SQL validation
• Code generation ile boilerplate elimination
• Stream-based reactive queries

React Native Solutions

react-native-sqlite-storage

• iOS ve Android için unified API
• Promise-based ve callback-based operations
• WAL mode support
• Encryption capabilities

WatermelonDB

• Reactive database with Observable patterns
• Lazy loading ve performance optimization
• Multi-threaded architecture
• Sync protokolü ile backend integration

Xamarin - SQLite.NET

• C# ile native SQLite binding
• ORM capabilities ve LINQ queries
• Encryption support (SQLCipher)
• Cross-platform code sharing

NoSQL Çözümler

Core Data (iOS)

Apple'ın object graph management ve persistence framework'ü olan Core Data, iOS ve macOS uygulamaları için kapsamlı data modeling çözümü sunar.

Core Components

NSManagedObject

• Entity modeling ve attribute definitions
• Relationship management (to-one, to-many)
• Validation rules ve custom validation
• Key-Value Coding (KVC) compliance

NSManagedObjectContext

• Change tracking ve dirty checking
• Undo/redo functionality
• Save operations ve error handling
• Parent-child context hierarchy

NSPersistentStore

• SQLite, Binary, In-Memory, XML storage options
• Store coordination ve multiple store types
• Encryption ve data protection
• CloudKit integration

Advanced Features

Performance Optimizations

• Faulting mechanism ile lazy loading
• Batch processing operations
• NSFetchedResultsController ile efficient UI updates
• Predicate optimization

CloudKit Integration

• Automatic cloud sync
• Schema mirroring
• Conflict resolution strategies
• Privacy ve data sharing controls

Realm Database

Modern object database olan Realm, live objects, automatic relationships ve real-time synchronization özellikleriyle öne çıkar.

Platform Support

• Native iOS/Android: Swift, Objective-C, Java, Kotlin
• Flutter: realm_dart package
• React Native: @realm/react
• Xamarin: Realm.NET

Core Features

Live Objects

// Realm live object örneği
let results = realm.objects(Person.self)
// Otomatik UI güncellemeleri
notificationToken = results.observe { changes in
    switch changes {
    case .initial:
        // İlk yüklemede
    case .update(_, let deletions, let insertions, let modifications):
        // Data değişikliklerinde otomatik UI güncellemeleri
    case .error(let error):
        // Error handling
    }
}

Advanced Capabilities

• MVCC (Multi-Version Concurrency Control)
• Zero-copy architecture
• Encryption at rest
• Schema versioning ve migration
• Full-text search capabilities

Realm Sync (Cloud)

• Real-time data synchronization
• Offline-first with automatic conflict resolution
• User authentication ve authorization
• Partitioned realms for data isolation

Key-Value Storage Solutions

Platform-Specific Options

Android

SharedPreferences

• XML-based key-value storage
• Type-safe değer saklama
• Commit vs apply operations
• Mode options (private, readable, writable)

Jetpack DataStore

• SharedPreferences'ın modern alternatifi
• Coroutines ve Flow integration
• Protocol Buffers support
• Type safety ve consistency

EncryptedSharedPreferences

• AES-256 encryption
• Master key yönetimi
• Automatic key rotation

iOS

UserDefaults

• Property list tabanlı storage
• NSCoding compliance
• Synchronization ve iCloud sync
• Suite-based grouping

Keychain Services

• Secure credential storage
• Biometric authentication integration
• Access control ve sharing options
• Cross-app data sharing capabilities

Cross-Platform Key-Value Stores

MMKV (Tencent)

• High-performance key-value store
• Memory-mapped file I/O
• Multi-process safe
• Encryption support
• iOS, Android, Flutter, React Native support

Hive (Flutter)

• Pure Dart NoSQL database
• Box-based organization
• Type adapters ve code generation
• Encryption capabilities

Performance Considerations

Database Architecture Overview

Performance Optimization Flow

Indexing Strategies

• Primary index optimization
• Composite index design
• Full-text search indexes
• Query plan analysis

Memory Management

• Object lifecycle management
• Cache size tuning
• Memory pressure handling
• Background cleanup strategies

Connection Management

• Connection pooling
• Thread safety
• Transaction management
• Deadlock prevention

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Modern mobil uygulamalarda doğru database seçimi, uygulama gereksinimlerine, platform kısıtlarına ve performans hedeflerine bağlıdır. SQL tabanlı çözümler complex queries ve ACID compliance gerektiren senaryolarda, NoSQL çözümler ise rapid development ve flexible schema ihtiyaçlarında tercih edilmelidir.