HybridCache + Redis vs IMemoryCache

Caching is simple until you have more than one server.

One server                     Multiple servers
───────────                    ────────────────
IMemoryCache                   ??? 
(fast, local)                  (local caches diverge)

HybridCache (.NET 9) solves this cleanly.

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The Three Layers

┌─────────────────────────────────────┐
│           HybridCache               │
│  ┌─────────────┐   ┌─────────────┐  │
│  │ IMemoryCache│ + │  Redis (L2) │  │
│  │    (L1)     │   │             │  │
│  └─────────────┘   └─────────────┘  │
└─────────────────────────────────────┘

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Quick Comparison

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How HybridCache Works

Get "product:42"
        │
        ▼
   L1 (Memory)? ──yes──▶ return
        │ no
        ▼
   L2 (Redis)?  ──yes──▶ store in L1 → return
        │ no
        ▼
   Factory (DB) ──▶ store L1 + L2 → return

One API. L1 + L2 + stampede protection.

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Minimal Setup

// Program.cs
builder.Services.AddHybridCache();

// Optional: use Redis as L2
builder.Services.AddStackExchangeRedisCache(options =>
{
    options.Configuration = "localhost:6379";
});

public class ProductService(HybridCache cache, AppDbContext db)
{
    public async Task<Product?> GetAsync(int id, CancellationToken ct = default)
    {
        return await cache.GetOrCreateAsync(
            $"product:{id}",
            async token => await db.Products.FindAsync([id], token),
            cancellationToken: ct);
    }
}

That’s it.

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Does It Fit with SQLite?

Yes - they solve different problems.

SQLite          →  persistent relational data
HybridCache     →  fast temporary cache in front of data

Common pattern:

Request
   │
   ▼
HybridCache (L1 memory + optional L2 Redis)
   │ miss
   ▼
SQLite (or SQL Server)

You can even run HybridCache with only L1 (no Redis) for single-instance apps that still use SQLite.

// No Redis registered → HybridCache uses memory only
builder.Services.AddHybridCache();

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When to Use What

Single server / desktop / simple API?
        │
        ▼
IMemoryCache  or  HybridCache (L1 only)

Multiple servers / containers?
        │
        ▼
HybridCache + Redis

Need cache to survive restarts + shared?
        │
        ▼
Redis (via HybridCache or IDistributedCache)

---

Other Alternatives

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Final Takeaway

IMemoryCache     →  fast, local, simple
Redis            →  shared, durable
HybridCache      →  fast + shared (L1 + L2)

Start with HybridCache.
Add Redis when you actually have more than one instance.

SQLite and HybridCache work well together:
SQLite holds the data, HybridCache makes the hot paths fast.