EF Core Second Level Cache Interceptor

Second-level caching is a query cache. The results of Entity Framework (EF) commands are stored in the cache so that the same EF commands will retrieve their data from the cache rather than executing them against the database again.

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How to Use

Using the second-level cache involves three mandatory steps: installing a provider, registering it, and adding the interceptor to your DbContext.

1. Install a Preferred Cache Provider

First, you need to add the main package:

dotnet add package EFCoreSecondLevelCacheInterceptor

This library supports multiple caching providers, each available as a separate NuGet package. You must install at least one.

• In-Memory (Built-in): A simple in-memory cache provider.

  dotnet add package EFCoreSecondLevelCacheInterceptor.MemoryCache

• StackExchange.Redis: Uses Redis with a preconfigured MessagePack serializer.

  dotnet add package EFCoreSecondLevelCacheInterceptor.StackExchange.Redis

• FusionCache: Implements FusionCache as a cache provider.

  dotnet add package EFCoreSecondLevelCacheInterceptor.FusionCache

• HybridCache: Implements .NET's HybridCache.

  dotnet add package EFCoreSecondLevelCacheInterceptor.HybridCache

• EasyCaching.Core: A provider for the EasyCaching.Core library.

  dotnet add package EFCoreSecondLevelCacheInterceptor.EasyCaching.Core

• CacheManager.Core: A provider for the CacheManager.Core library.

  dotnet add package EFCoreSecondLevelCacheInterceptor.CacheManager.Core

• Custom: You can also implement your own provider.

2. Register the Cache Provider and Interceptor

In your Startup.cs or Program.cs, you need to register the EF Core second-level cache services and configure your chosen provider.

Example: Using the Built-in In-Memory Provider

public void ConfigureServices(IServiceCollection services)
{
    // 1. Add EF Core Second Level Cache services
    services.AddEFSecondLevelCache(options =>
        options.UseMemoryCacheProvider().ConfigureLogging(true).UseCacheKeyPrefix("EF_")
               // Fallback on db if the caching provider fails.
               .UseDbCallsIfCachingProviderIsDown(TimeSpan.FromMinutes(1))
    );

    // 2. Add your DbContext
    var connectionString = Configuration["ConnectionStrings:ApplicationDbContextConnection"];
    services.AddConfiguredMsSqlDbContext(connectionString);

    services.AddControllersWithViews();
}

(For detailed configuration examples of other providers, see the Available Cache Providers section below.)

3. Add the Interceptor to Your DbContext

Modify your DbContext registration to add the SecondLevelCacheInterceptor. This service is automatically registered and available via dependency injection.

public static class MsSqlServiceCollectionExtensions
{
    public static IServiceCollection AddConfiguredMsSqlDbContext(this IServiceCollection services, string connectionString)
    {
        services.AddDbContextPool<ApplicationDbContext>((serviceProvider, optionsBuilder) =>
                optionsBuilder
                    .UseSqlServer(
                        connectionString,
                        sqlServerOptionsBuilder =>
                        {
                            sqlServerOptionsBuilder
                                .CommandTimeout((int)TimeSpan.FromMinutes(3).TotalSeconds)
                                .EnableRetryOnFailure()
                                .MigrationsAssembly(typeof(MsSqlServiceCollectionExtensions).Assembly.FullName);
                        })
                    // Add the interceptor
                    .AddInterceptors(serviceProvider.GetRequiredService<SecondLevelCacheInterceptor>()));
        return services;
    }
}

4. Make Queries Cacheable

To cache a query, use the .Cacheable() extension method. It can be placed anywhere in the LINQ query chain.

var post = context.Posts
                   .Where(x => x.Id > 0)
                   .OrderBy(x => x.Id)
                   .Cacheable() // Mark this query to be cached
                   .FirstOrDefault();  // Async methods are also supported.

The Cacheable() method uses global settings by default, but you can override them for a specific query:

var post = context.Posts
                   .Where(x => x.Id > 0)
                   .OrderBy(x => x.Id)
                   // Override global settings for this query
                   .Cacheable(CacheExpirationMode.Sliding, TimeSpan.FromMinutes(5))
                   .FirstOrDefault();

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How to Verify It's Working

To confirm that the interceptor is working, you should enable logging.

1. Enable Logging in the Configuration Set ConfigureLogging(true) during service registration.

services.AddEFSecondLevelCache(options =>
    options.UseMemoryCacheProvider().ConfigureLogging(true)
);

2. Set Log Level to Debug In your appsettings.json, ensure the log level is set to Debug.

{
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "System": "Debug",
      "Microsoft": "Debug"
    }
  }
}

When you run a cacheable query for the first time, the data is fetched from the database and cached. On subsequent executions, you should see log messages indicating a cache hit:

Suppressed result with a TableRows[ee20d2d7-ffc7-4ff9-9484-e8d4eecde53e] from the cache[KeyHash: EB153BD4, CacheDependencies: Page.].
Using the TableRows[ee20d2d7-ffc7-4ff9-9484-e8d4eecde53e] from the cache.

Notes:

• The Suppressed the result with the TableRows message confirms the caching interceptor is working.
• You will still see an Executed DbCommand log message from EF Core, but this is expected behavior.
• You can also use a database profiler to verify that the query is only executed against the database on the first run.
• For more direct access to library events, you can pass an action to the ConfigureLogging method. See the Logging Events section for more details.

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Caching Strategies

You can control caching globally or on a per-query basis.

Global Caching

Instead of marking individual queries with .Cacheable(), you can define a global caching policy.

Caching All Queries

To cache every query in the application, use CacheAllQueries().

services.AddEFSecondLevelCache(options =>
{
    options.UseMemoryCacheProvider().UseCacheKeyPrefix("EF_");
    options.CacheAllQueries(CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30));
});

• If you use CacheAllQueries(), you don't need to call .Cacheable() on individual queries.
• A specific .Cacheable() call on a query will override the global setting.
• To exclude a specific query from global caching, use the .NotCacheable() method.

Caching Queries by Type or Table Name

To cache queries that involve specific entity types or database tables, use CacheQueriesContainingTypes or CacheQueriesContainingTableNames.

services.AddEFSecondLevelCache(options =>
{
    options.UseMemoryCacheProvider()
           .CacheQueriesContainingTableNames(
               CacheExpirationMode.Absolute, TimeSpan.FromMinutes(30), TableNameComparison.ContainsOnly,
               "posts", "products", "users"
            );
});

• You can also exclude specific types or table names from caching using CacheAllQueriesExceptContainingTypes or CacheAllQueriesExceptContainingTableNames.

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Cache Invalidation

This library automatically invalidates cache entries when it detects CRUD operations (via its interceptor).

Automatic Invalidation

When you use SaveChanges() or SaveChangesAsync(), the interceptor identifies which tables have been modified and invalidates all cached queries that depend on those tables. No additional configuration is needed.

Limitation: ExecuteUpdate and ExecuteDelete EF Core does not trigger interceptors for bulk operations like ExecuteUpdate and ExecuteDelete for performance reasons. These methods execute raw SQL directly, bypassing EF Core's change tracking and related events. Therefore, cache invalidation will not happen automatically for these operations. You must invalidate the cache manually.

Manual Invalidation

You can manually invalidate the cache by injecting the IEFCacheServiceProvider.

• Invalidate the entire cache:

  _cacheServiceProvider.ClearAllCachedEntries();

• Invalidate cache entries related to specific tables: This is useful if you are using an external tool like SqlTableDependency to monitor database changes.

  // The prefix "EF_" should match your configured UseCacheKeyPrefix.
  var tableNames = new HashSet<string> { "EF_TableName1", "EF_TableName2" };
  _cacheServiceProvider.InvalidateCacheDependencies(new EFCacheKey(tableNames));

Invalidation Notifications

To receive notifications when cache entries are invalidated, use the NotifyCacheInvalidation method.

services.AddEFSecondLevelCache(options =>
{
   options.UseMemoryCacheProvider()
          .NotifyCacheInvalidation(invalidationInfo =>
          {
              var logger = invalidationInfo.ServiceProvider
                                           .GetRequiredService<ILoggerFactory>()
                                           .CreateLogger("NotifyCacheInvalidation");
              var message = invalidationInfo.ClearAllCachedEntries
                  ? "Invalidated all cache entries!"
                  : $"Invalidated dependencies: [{string.Join(", ", invalidationInfo.CacheDependencies)}]";
              logger.LogWarning(message);
          });
});

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Advanced Configuration

Skipping Caching

You can define rules to skip caching for certain queries based on their command text or results.

• Skip by Command Text:

  services.AddEFSecondLevelCache(options =>
  {
      options.SkipCachingCommands(commandText =>
          commandText.Contains("NEWID()", StringComparison.InvariantCultureIgnoreCase));
  });

• Skip by Result:

  services.AddEFSecondLevelCache(options =>
  {
      // Don't cache null values or empty result sets.
      options.SkipCachingResults(result =>
          result.Value == null || (result.Value is EFTableRows rows && rows.RowsCount == 0));
  });

Skipping Invalidation

In some cases, you may want to prevent a command from invalidating the cache, such as when updating a view counter.

services.AddEFSecondLevelCache(options =>
{
    options.SkipCacheInvalidationCommands(commandText =>
        // Assumes a command that only updates a post's view count contains this text.
        commandText.Contains("UPDATE [Posts] SET [Views]", StringComparison.InvariantCultureIgnoreCase));
});

Overriding Cache Policy

Use OverrideCachePolicy() to dynamically change the caching policy for a query at runtime.

services.AddEFSecondLevelCache(options =>
{
    options.OverrideCachePolicy(context =>
    {
        // Don't cache any CRUD commands
        if (context.IsCrudCommand)
        {
            return null;
        }

        // Use a "never remove" policy for queries on the 'posts' table
        if (context.CommandTableNames.Contains("posts"))
        {
            return new EFCachePolicy().ExpirationMode(CacheExpirationMode.NeverRemove);
        }

        // Use the default calculated policy for all other queries
        return null;
    });
});

Logging Events

You can subscribe to caching events directly instead of parsing log files.

.ConfigureLogging(enable: environment.IsDevelopment(), cacheableEvent: args =>
{
    switch (args.EventId)
    {
        case CacheableLogEventId.CacheHit:
            break;
        case CacheableLogEventId.QueryResultCached:
            break;
        case CacheableLogEventId.QueryResultInvalidated:
            // Example of logging a specific event
            args.ServiceProvider.GetRequiredService<ILoggerFactory>()
                .CreateLogger(nameof(EFCoreSecondLevelCacheInterceptor))
                .LogWarning("{EventId} -> {Message} -> {CommandText}",
                            args.EventId, args.Message, args.CommandText);
            break;
        // ... handle other events
    }
})

Other Configurations

• Custom Hash Provider: Replace the default xxHash algorithm by implementing IEFHashProvider and registering it with options.UseCustomHashProvider<T>().
• Custom JsonSerializerOptions: Control serialization behavior by passing JsonSerializerOptions to options.UseJsonSerializerOptions(options).
• Disable Interceptor: Temporarily disable the interceptor via options.EnableCachingInterceptor(false).
• Skip DbContexts: Exclude certain DbContext types from caching with options.SkipCachingDbContexts().

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Available Cache Providers

Below are setup examples for the various supported cache providers.

1. EFCoreSecondLevelCacheInterceptor.StackExchange.Redis

This provider uses StackExchange.Redis and is preconfigured with a MessagePack serializer.

var redisOptions = new ConfigurationOptions
{
     EndPoints = { { "127.0.0.1", 6379 } },
     AllowAdmin = true,
     ConnectTimeout = 10000
};

services.AddEFSecondLevelCache(options =>
    options.UseStackExchangeRedisCacheProvider(redisOptions, TimeSpan.FromMinutes(5)));

2. EFCoreSecondLevelCacheInterceptor.FusionCache

This provider uses FusionCache.

// 1. Add FusionCache services with desired options
services.AddFusionCache()
        .WithOptions(options =>
        {
            options.DefaultEntryOptions = new FusionCacheEntryOptions
            {
                Duration = TimeSpan.FromMinutes(1),
                IsFailSafeEnabled = true,
                FailSafeMaxDuration = TimeSpan.FromHours(2),
                // ... other FusionCache options
            };
        });

// 2. Add the EF Core Caching provider
services.AddEFSecondLevelCache(options => options.UseFusionCacheProvider());

3. EFCoreSecondLevelCacheInterceptor.HybridCache

This provider uses the new .NET HybridCache.

services.AddEFSecondLevelCache(options => options.UseHybridCacheProvider());

4. Using EasyCaching.Core

This allows you to use EasyCaching.Core as a highly configurable cache manager.

• In-Memory with EasyCaching.Core:

  const string providerName = "InMemory1";
  services.AddEFSecondLevelCache(options =>
      options.UseEasyCachingCoreProvider(providerName, isHybridCache: false)
             .UseCacheKeyPrefix("EF_")
  );
  
  // Add EasyCaching.Core in-memory provider
  services.AddEasyCaching(options =>
  {
      options.UseInMemory(config =>
      {
          config.DBConfig = new InMemoryCachingOptions { SizeLimit = 10000 };
          config.MaxRdSecond = 120;
      }, providerName);
  });

• Redis with EasyCaching.Core: First, install the required packages: EasyCaching.Redis and EasyCaching.Serialization.MessagePack.

  const string providerName = "Redis1";
  services.AddEFSecondLevelCache(options =>
      options.UseEasyCachingCoreProvider(providerName, isHybridCache: false)
             .UseCacheKeyPrefix("EF_")
  );
  
  // Add EasyCaching.Core Redis provider
  services.AddEasyCaching(option =>
  {
      option.UseRedis(config =>
      {
          config.DBConfig.Endpoints.Add(new EasyCaching.Core.Configurations.ServerEndPoint("127.0.0.1", 6379));
          config.SerializerName = "Pack";
      }, providerName)
      .WithMessagePack("Pack"); // Configure MessagePack serializer
  });

• Dynamic Provider with EasyCaching.Core for Multi-tenancy: You can dynamically select a cache provider based on the current context, such as a tenant ID from an HTTP request header.

  services.AddEFSecondLevelCache(options =>
      options.UseEasyCachingCoreProvider(
         (serviceProvider, cacheKey) => "redis-db-" + serviceProvider.GetRequiredService<IHttpContextAccessor>().HttpContext.Request.Headers["tenant-id"],
         isHybridCache: false)
  );

5. Using CacheManager.Core

This allows you to use CacheManager.Core as a cache manager. Note: This library is not actively maintained.

• In-Memory with CacheManager.Core: First, install: CacheManager.Core, CacheManager.Microsoft.Extensions.Caching.Memory, and CacheManager.Serialization.Json.

  services.AddEFSecondLevelCache(options => options.UseCacheManagerCoreProvider());
  
  // Add CacheManager.Core services
  services.AddSingleton(typeof(ICacheManager<>), typeof(BaseCacheManager<>));
  services.AddSingleton(typeof(ICacheManagerConfiguration),
      new CacheManager.Core.CacheConfigurationBuilder()
              .WithJsonSerializer()
              .WithMicrosoftMemoryCacheHandle("MemoryCache1")
              .Build());

• Redis with CacheManager.Core: First, install the CacheManager.StackExchange.Redis package.

  services.AddEFSecondLevelCache(options => options.UseCacheManagerCoreProvider());
  
  // Add CacheManager.Core Redis services
  const string redisConfigurationKey = "redis";
  services.AddSingleton(typeof(ICacheManagerConfiguration),
      new CacheManager.Core.CacheConfigurationBuilder()
          .WithJsonSerializer()
          .WithUpdateMode(CacheUpdateMode.Up)
          .WithRedisConfiguration(redisConfigurationKey, config =>
          {
              config.WithAllowAdmin()
                    .WithDatabase(0)
                    .WithEndpoint("localhost", 6379)
                    .EnableKeyspaceEvents();
          })
          .WithRedisCacheHandle(redisConfigurationKey)
          .Build());
  services.AddSingleton(typeof(ICacheManager<>), typeof(BaseCacheManager<>));

6. Using a Custom Cache Provider

If the provided cache providers don't meet your needs, you can implement the IEFCacheServiceProvider interface and then register it using the options.UseCustomCacheProvider<T>() method.

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Guidance and Best Practices

When to Use

Good candidates for query caching are global site settings and public data, such as infrequently changing articles or comments. It can also be beneficial to cache data specific to a user, so long as the cache expires frequently enough relative to the size of the user base that memory consumption remains acceptable. Small, per-user data that changes frequently is better held in other stores like user claims, which are stored in cookies, than in this cache.

Scope

This cache is scoped to the application, not the current user. It does not use session variables. Accordingly, when retrieving cached per-user data, be sure your queries include a filter for the user ID, such as .Where(x => x.UserId == id).

Invalidation

The cache is updated when an entity is changed (inserted, updated, or deleted) via a DbContext that uses this interceptor. If the database is modified through other means, such as a stored procedure, a trigger, or another application, the cache will become stale.

Transactions

To avoid complications, all queries inside an explicit transaction (context.Database.BeginTransaction()) will not be cached by default. However, cache invalidation for CRUD operations within the transaction will still occur. You can override this behavior and allow caching within explicit transactions by using the .AllowCachingWithExplicitTransactions(true) setting.

Database Provider Compatibility

Some database providers do not natively support special data types such as DateTimeOffset or TimeSpan. For these scenarios, you will need to configure the appropriate value converters in your DbContext.

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How to Upgrade to Version 5

To support more advanced caching providers, this library was split into multiple assemblies and NuGet packages in version 5.

1. Remove the old dependency: EFCoreSecondLevelCacheInterceptor.
2. Add the new main package:

   dotnet add package EFCoreSecondLevelCacheInterceptor

3. Add a provider package: The main package no longer includes a built-in provider. You must install one of the new provider packages.
   • For the previous built-in In-Memory cache, install:

     dotnet add package EFCoreSecondLevelCacheInterceptor.MemoryCache

   • For the previous EasyCaching.Core provider, install:

     dotnet add package EFCoreSecondLevelCacheInterceptor.EasyCaching.Core

   • For the previous CacheManager.Core provider, install:

     dotnet add package EFCoreSecondLevelCacheInterceptor.CacheManager.Core

If you were using a custom cache provider via options.UseCustomCacheProvider<T>(), you do not need to install a new provider package.

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Samples

• Console App Sample
• ASP.NET Core App Sample
• Project Tests