Partial caching

By Optimizely Education
Published: Mar 3, 2026
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Outline

At a glance

What it is: Caching reusable fragments like blocks and product cards.
Why it matters: Reduces rendering time and server load.
Core APIs: IMemoryCache, IDistributedCache, OutputCache.
Optimizely advantage: IContentCacheKeyService enables smart invalidation.
DXP rule: Use distributed caching in multi-node environments.

This module provides a technical deep dive into partial (fragment) caching within ASP.NET Core-based Optimizely solutions.

1. In-Memory Caching (IMemoryCache)

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

public class MyService
{
    private readonly IMemoryCache _memoryCache;

    public MyService(IMemoryCache memoryCache)
    {
        _memoryCache = memoryCache;
    }

    public string GetCachedData(string key)
    {
        if (!_memoryCache.TryGetValue(key, out string cachedValue))
        {
            cachedValue = FetchDataFromDatabase();

            var cacheEntryOptions = new MemoryCacheEntryOptions()
                .SetSlidingExpiration(TimeSpan.FromMinutes(5))
                .SetAbsoluteExpiration(TimeSpan.FromMinutes(30));

            _memoryCache.Set(key, cachedValue, cacheEntryOptions);
        }

        return cachedValue;
    }
}
    

2. Distributed Caching (IDistributedCache)

// Program.cs
builder.Services.AddStackExchangeRedisCache(options =&gt;
{
    options.Configuration = builder.Configuration.GetConnectionString("RedisCache");
    options.InstanceName = "OptimizelyApp_";
});
    

public class MyService
{
    private readonly IDistributedCache _distributedCache;

    public MyService(IDistributedCache distributedCache)
    {
        _distributedCache = distributedCache;
    }

    public async Task<string> GetCachedDataAsync(string key)
    {
        byte[] encodedValue = await _distributedCache.GetAsync(key);
        string cachedValue;

        if (encodedValue != null)
        {
            cachedValue = Encoding.UTF8.GetString(encodedValue);
        }
        else
        {
            cachedValue = await FetchDataFromDatabaseAsync();
            byte[] valueToCache = Encoding.UTF8.GetBytes(cachedValue);

            var options = new DistributedCacheEntryOptions()
                .SetSlidingExpiration(TimeSpan.FromMinutes(5))
                .SetAbsoluteExpiration(TimeSpan.FromMinutes(30));

            await _distributedCache.SetAsync(key, valueToCache, options);
        }

        return cachedValue;
    }
}
    