Realm vs. LiteDB vs. SQLite: A Performance and Usability Deep Dive for .NET MAUI

🔍 Introduction

Mobile and cross-platform apps often need a fast, reliable, local data store. .NET MAUI apps (iOS/Android/desktop) commonly use:

• Realm — object database (mobile-first), reactive, great for complex object graphs and realtime updates.
• LiteDB — lightweight, single-file NoSQL document DB (BSON-like), easy to embed.
• SQLite — classic relational DB; extremely portable; broad ecosystem (sqlite-net-pcl, Microsoft.Data.Sqlite, etc.).

Each one fits different scenarios. Below we compare them on performance, concurrency, features, developer ergonomics, and show how to get started in .NET MAUI.

📊 Quick Feature Comparison

✅ Real Use Cases

• Realm
  • Offline-first social feed with complex linked objects, live updates, and eventual cloud sync (MongoDB Realm).
  • Chat app where reactive change notifications push UI updates instantly.
• LiteDB
  • Simple single-user utility app storing JSON-like documents (notes, preferences).
  • Desktop tools and prototypes where zero-ops persistence is ideal.
• SQLite
  • Apps requiring relational modelling and complex SQL queries (analytics, reporting, relational data).
  • Cross-platform apps where portability and tooling (DB viewers / ORMs) matter most.

⚙️ How to choose (short guide)

• Need live objects & sync → Realm.
• Want single-file, document DB, super easy → LiteDB.
• Need SQL, strong tooling, or relational queries → SQLite.

🛠️ Step-by-step: Getting started in .NET MAUI

For each library: show install, simple model, init, CRUD. Use FileSystem.AppDataDirectory (MAUI) for DB file location.

1) Realm (local, reactive)

Install

Model

Initialize & CRUD (example usage in MAUI)

Notes

• Realm objects are live — updates reflect automatically.
• Realm has GetInstanceAsync, sync features with MongoDB Realm if you need cloud sync.

2) LiteDB (embedded document DB)

Install

Model (POCO)

Usage

Notes

• LiteDB works well for simple document storage.
• Concurrent access: LiteDB supports multiple readers, single writer — be careful in multi-thread scenarios (file locks).

3) SQLite (sqlite-net-pcl) — classic relational approach

Install

Model (attributes)

Usage (async)

Notes

• Use WAL journal mode for better concurrency (set via connection string / PRAGMA).
• Mature ecosystem: editors, tools, ORMs, migrations.

🧪 Performance testing tips (how to benchmark)

If you want a fair comparison on your device(s), measure with microbenchmarks:

1. Define test scenarios: bulk insert (10k items), random reads, complex queries, update throughput, concurrent reads+writes.
2. Use Stopwatch and repeat each test multiple times, average results.
3. Warm-up the DB (first-run JIT + initial file creation can bias results).
4. Measure memory via platform tools (Android Profiler, iOS Instruments).
5. Consider real-device tests over emulators for mobile accuracy.
6. Optionally use BenchmarkDotNet (for desktop) for controlled benchmarking.

Example benchmark pseudo:

Important: concurrency and file I/O behavior differ by platform — test on target devices.

⚠️ Concurrency & Data Safety Summary

• Realm: built for mobile concurrency; each thread sees a consistent snapshot; supports safe cross-thread reads and notifications.
• SQLite: with WAL mode supports multiple readers + one writer; use locking or proper async patterns.
• LiteDB: supports multiple readers, single writer; file-level locks may block under heavy concurrent writes.

💡 Practical Recommendations (Conclusion)

• Choose Realm if you want:
  • Reactive UI updates (live objects)
  • Built-in sync with MongoDB Realm later
  • Excellent mobile-optimized read/write performance for complex object graphs
• Choose LiteDB if you want:
  • Simple, tiny, single-file document DB
  • Fast prototyping and minimal dependency footprint
  • Desktop/utility apps or small MAUI apps
• Choose SQLite (sqlite-net-pcl) if you want:
  • Max portability and tooling
  • Relational data model and complex SQL queries
  • Mature ecosystem and integration with many tools

📚 References & Further Reading

• Realm .NET docs — https://www.mongodb.com/docs/realm/sdk/dotnet/
• LiteDB — https://www.litedb.org/ / https://github.com/mbdavid/LiteDB
• sqlite-net-pcl — https://github.com/praeclarum/sqlite-net
• Microsoft docs (MAUI file APIs) — https://learn.microsoft.com/dotnet/maui/platform-integration/files
• Android App performance tips — profiling (Android Profiler)
• iOS Instruments — performance and memory profiling

🔁 TL;DR (cheat-sheet) 🧾

• Need live, reactive objects & future cloud sync → Realm ✅
• Need tiny, easy document store → LiteDB ✅
• Need SQL + tools + relational queries → SQLite ✅