SQL Server

dotnet add package ActionCache.SqlServer

builder.Services.AddActionCache(options =>
{
    options.UseSqlServerCache(sql =>
    {
        sql.ConnectionString = configuration.GetConnectionString("Cache");
        sql.SchemaName = "dbo";
        sql.TableName = "DistributedCache";
    });
});

The delegate configures SqlServerCacheOptions, the same type Microsoft.Extensions.Caching.SqlServer uses.

The table

This backend stores entries in the standard distributed-cache table, which you create with the dotnet-sql-cache tool:

dotnet tool install --global dotnet-sql-cache
dotnet sql-cache create "<connection string>" dbo DistributedCache

Locking

sp_getapplock / sp_releaseapplock, session-scoped. That is also what backs UseDistributedSingleFlight() when Redis is not registered.

A session-scoped lock cannot expire while held, and a process that dies releases its locks by disconnecting — so the lease duration in ActionCacheSingleFlightOptions has nothing to enforce here. It applies to Redis, where the lock is a key with a TTL.

Cancellation

The SQL Server backend forwards the CancellationToken to the underlying commands, so a client that disconnects stops work in flight rather than letting it run to completion.

When to use it

A stack that already runs SQL Server and would rather not add Redis. It is slower than Redis for cache traffic, but it is one less thing to operate.