mgravell · Sep 14, 2026 · Sep 14, 2026 · Sep 14, 2026 · Oct 5, 2026 · Oct 15, 2026
diff --git a/.github/workflows/integration.yml b/.github/workflows/integration.yml
@@ -39,10 +39,10 @@ jobs:
         fail-fast: false
         matrix:
           # Full version set runs only on the nightly schedule; PRs and pushes
-          # test a reduced set (7.2 LTS, 7.4 LTS, 8.2 LTS, 8.8, 8.10 current stable) to keep CI fast.
+          # test a reduced set (7.2 LTS, 7.4 LTS, 8.2 LTS, 8.8, 8.10 current stable, 8.12 preview) to keep CI fast.
           redis-version: ${{ fromJSON(github.event_name == 'schedule'
-            && '["8.10", "8.8", "8.6", "8.4", "8.2", "7.4", "7.2", "6.2"]'
-            || '["8.10", "8.8", "8.2", "7.4", "7.2"]') }}
+            && '["8.12", "8.10", "8.8", "8.6", "8.4", "8.2", "7.4", "7.2", "6.2"]'
+            || '["8.12", "8.10", "8.8", "8.2", "7.4", "7.2"]') }}
           dotnet-version: ['8.0', '9.0', '10.0']
       name: Redis ${{ matrix.redis-version }}; .NET ${{ matrix.dotnet-version }};
       steps:

diff --git a/src/NRedisStack/CountMinSketch/CmsCommandBuilder.cs b/src/NRedisStack/CountMinSketch/CmsCommandBuilder.cs
@@ -37,11 +37,36 @@ public static SerializedCommand InitByDim(RedisKey key, long width, long depth)
         return new(CommandCategories.WriteAccumulating, CMS.INITBYDIM, key, width, depth);
     }
 
+    public static SerializedCommand InitByDim(RedisKey key, long width, long depth, int cellSize)
+    {
+        List<object> args = [key, width, depth];
+        AddCellSize(args, cellSize);
+
+        return new(CommandCategories.WriteAccumulating, CMS.INITBYDIM, args);
+    }
+
     public static SerializedCommand InitByProb(RedisKey key, double error, double probability)
     {
         return new(CommandCategories.WriteAccumulating, CMS.INITBYPROB, key, error, probability);
     }
 
+    public static SerializedCommand InitByProb(RedisKey key, double error, double probability, int cellSize)
+    {
+        List<object> args = [key, error, probability];
+        AddCellSize(args, cellSize);
+
+        return new(CommandCategories.WriteAccumulating, CMS.INITBYPROB, args);
+    }
+
+    private static void AddCellSize(List<object> args, int cellSize)
+    {
+        if (cellSize is not (1 or 2 or 4 or 8))
+            throw new ArgumentOutOfRangeException(nameof(cellSize), cellSize, "Cell size must be 1, 2, 4, or 8.");
+
+        args.Add(CmsArgs.CELL_SIZE);
+        args.Add(cellSize);
+    }
+
     public static SerializedCommand Merge(RedisValue destination, long numKeys, RedisValue[] source,
         long[]? weight = null)
     {

diff --git a/src/NRedisStack/CountMinSketch/CmsCommands.cs b/src/NRedisStack/CountMinSketch/CmsCommands.cs
@@ -37,12 +37,24 @@ public bool InitByDim(RedisKey key, long width, long depth)
         return _db.Execute(CmsCommandBuilder.InitByDim(key, width, depth)).OKtoBoolean();
     }
 
+    /// <inheritdoc/>
+    public bool InitByDim(RedisKey key, long width, long depth, int cellSize)
+    {
+        return _db.Execute(CmsCommandBuilder.InitByDim(key, width, depth, cellSize)).OKtoBoolean();
+    }
+
     /// <inheritdoc/>
     public bool InitByProb(RedisKey key, double error, double probability)
     {
         return _db.Execute(CmsCommandBuilder.InitByProb(key, error, probability)).OKtoBoolean();
     }
 
+    /// <inheritdoc/>
+    public bool InitByProb(RedisKey key, double error, double probability, int cellSize)
+    {
+        return _db.Execute(CmsCommandBuilder.InitByProb(key, error, probability, cellSize)).OKtoBoolean();
+    }
+
     /// <inheritdoc/>
     public bool Merge(RedisValue destination, long numKeys, RedisValue[] source, long[]? weight = null)
     {

diff --git a/src/NRedisStack/CountMinSketch/CmsCommandsAsync.cs b/src/NRedisStack/CountMinSketch/CmsCommandsAsync.cs
@@ -37,12 +37,24 @@ public async Task<bool> InitByDimAsync(RedisKey key, long width, long depth)
         return (await _db.ExecuteAsync(CmsCommandBuilder.InitByDim(key, width, depth))).OKtoBoolean();
     }
 
+    /// <inheritdoc/>
+    public async Task<bool> InitByDimAsync(RedisKey key, long width, long depth, int cellSize)
+    {
+        return (await _db.ExecuteAsync(CmsCommandBuilder.InitByDim(key, width, depth, cellSize))).OKtoBoolean();
+    }
+
     /// <inheritdoc/>
     public async Task<bool> InitByProbAsync(RedisKey key, double error, double probability)
     {
         return (await _db.ExecuteAsync(CmsCommandBuilder.InitByProb(key, error, probability))).OKtoBoolean();
     }
 
+    /// <inheritdoc/>
+    public async Task<bool> InitByProbAsync(RedisKey key, double error, double probability, int cellSize)
+    {
+        return (await _db.ExecuteAsync(CmsCommandBuilder.InitByProb(key, error, probability, cellSize))).OKtoBoolean();
+    }
+
     /// <inheritdoc/>
     public async Task<bool> MergeAsync(RedisValue destination, long numKeys, RedisValue[] source, long[]? weight = null)
     {

diff --git a/src/NRedisStack/CountMinSketch/ICmsCommands.cs b/src/NRedisStack/CountMinSketch/ICmsCommands.cs
@@ -44,6 +44,18 @@ public interface ICmsCommands
     /// <remarks><seealso href="https://redis.io/commands/cms.initbydim"/></remarks>
     bool InitByDim(RedisKey key, long width, long depth);
 
+    /// <summary>
+    /// Initializes a Count-Min Sketch to dimensions specified by user.
+    /// </summary>
+    /// <param name="key">TThe name of the sketch.</param>
+    /// <param name="width">Number of counters in each array. Reduces the error size.</param>
+    /// <param name="depth">Number of counter-arrays. Reduces the probability for an error
+    /// of a certain size (percentage of total count).</param>
+    /// <param name="cellSize">The number of bytes per cell (1, 2, 4, or 8).</param>
+    /// <returns><see langword="true"/> if if executed correctly, Error otherwise.</returns>
+    /// <remarks><seealso href="https://redis.io/commands/cms.initbydim"/></remarks>
+    bool InitByDim(RedisKey key, long width, long depth, int cellSize);
+
     /// <summary>
     /// Initializes a Count-Min Sketch to accommodate requested tolerances.
     /// </summary>
@@ -54,6 +66,17 @@ public interface ICmsCommands
     /// <remarks><seealso href="https://redis.io/commands/cms.initbyprob"/></remarks>
     bool InitByProb(RedisKey key, double error, double probability);
 
+    /// <summary>
+    /// Initializes a Count-Min Sketch to accommodate requested tolerances.
+    /// </summary>
+    /// <param name="key">The name of the sketch.</param>
+    /// <param name="error">Estimate size of error.</param>
+    /// <param name="probability">The desired probability for inflated count.</param>
+    /// <param name="cellSize">The number of bytes per cell (1, 2, 4, or 8).</param>
+    /// <returns><see langword="true"/> if if executed correctly, Error otherwise.</returns>
+    /// <remarks><seealso href="https://redis.io/commands/cms.initbyprob"/></remarks>
+    bool InitByProb(RedisKey key, double error, double probability, int cellSize);
+
     /// <summary>
     /// Merges several sketches into one sketch.
     /// </summary>

diff --git a/src/NRedisStack/CountMinSketch/ICmsCommandsAsync.cs b/src/NRedisStack/CountMinSketch/ICmsCommandsAsync.cs
@@ -44,6 +44,18 @@ public interface ICmsCommandsAsync
     /// <remarks><seealso href="https://redis.io/commands/cms.initbydim"/></remarks>
     Task<bool> InitByDimAsync(RedisKey key, long width, long depth);
 
+    /// <summary>
+    /// Initializes a Count-Min Sketch to dimensions specified by user.
+    /// </summary>
+    /// <param name="key">TThe name of the sketch.</param>
+    /// <param name="width">Number of counters in each array. Reduces the error size.</param>
+    /// <param name="depth">Number of counter-arrays. Reduces the probability for an error
+    /// of a certain size (percentage of total count).</param>
+    /// <param name="cellSize">The number of bytes per cell (1, 2, 4, or 8).</param>
+    /// <returns><see langword="true"/> if if executed correctly, Error otherwise.</returns>
+    /// <remarks><seealso href="https://redis.io/commands/cms.initbydim"/></remarks>
+    Task<bool> InitByDimAsync(RedisKey key, long width, long depth, int cellSize);
+
     /// <summary>
     /// Initializes a Count-Min Sketch to accommodate requested tolerances.
     /// </summary>
@@ -54,6 +66,17 @@ public interface ICmsCommandsAsync
     /// <remarks><seealso href="https://redis.io/commands/cms.initbyprob"/></remarks>
     Task<bool> InitByProbAsync(RedisKey key, double error, double probability);
 
+    /// <summary>
+    /// Initializes a Count-Min Sketch to accommodate requested tolerances.
+    /// </summary>
+    /// <param name="key">The name of the sketch.</param>
+    /// <param name="error">Estimate size of error.</param>
+    /// <param name="probability">The desired probability for inflated count.</param>
+    /// <param name="cellSize">The number of bytes per cell (1, 2, 4, or 8).</param>
+    /// <returns><see langword="true"/> if if executed correctly, Error otherwise.</returns>
+    /// <remarks><seealso href="https://redis.io/commands/cms.initbyprob"/></remarks>
+    Task<bool> InitByProbAsync(RedisKey key, double error, double probability, int cellSize);
+
     /// <summary>
     /// Merges several sketches into one sketch.
     /// </summary>

diff --git a/src/NRedisStack/CountMinSketch/Literals/CommandArgs.cs b/src/NRedisStack/CountMinSketch/Literals/CommandArgs.cs
@@ -3,4 +3,5 @@ namespace NRedisStack.CountMinSketch.Literals;
 internal class CmsArgs
 {
     public const string WEIGHTS = "WEIGHTS";
+    public const string CELL_SIZE = "CELL_SIZE";
 }
diff --git a/src/NRedisStack/PublicAPI/PublicAPI.Unshipped.txt b/src/NRedisStack/PublicAPI/PublicAPI.Unshipped.txt
@@ -1 +1,12 @@
 #nullable enable
+NRedisStack.CountMinSketch.DataTypes.CmsInformation.CellSize.get -> int
+NRedisStack.CmsCommands.InitByDim(StackExchange.Redis.RedisKey key, long width, long depth, int cellSize) -> bool
+NRedisStack.CmsCommands.InitByProb(StackExchange.Redis.RedisKey key, double error, double probability, int cellSize) -> bool
+NRedisStack.CmsCommandsAsync.InitByDimAsync(StackExchange.Redis.RedisKey key, long width, long depth, int cellSize) -> System.Threading.Tasks.Task<bool>!
+NRedisStack.CmsCommandsAsync.InitByProbAsync(StackExchange.Redis.RedisKey key, double error, double probability, int cellSize) -> System.Threading.Tasks.Task<bool>!
+NRedisStack.ICmsCommands.InitByDim(StackExchange.Redis.RedisKey key, long width, long depth, int cellSize) -> bool
+NRedisStack.ICmsCommands.InitByProb(StackExchange.Redis.RedisKey key, double error, double probability, int cellSize) -> bool
+NRedisStack.ICmsCommandsAsync.InitByDimAsync(StackExchange.Redis.RedisKey key, long width, long depth, int cellSize) -> System.Threading.Tasks.Task<bool>!
+NRedisStack.ICmsCommandsAsync.InitByProbAsync(StackExchange.Redis.RedisKey key, double error, double probability, int cellSize) -> System.Threading.Tasks.Task<bool>!
+static NRedisStack.CmsCommandBuilder.InitByDim(StackExchange.Redis.RedisKey key, long width, long depth, int cellSize) -> NRedisStack.RedisStackCommands.SerializedCommand!
+static NRedisStack.CmsCommandBuilder.InitByProb(StackExchange.Redis.RedisKey key, double error, double probability, int cellSize) -> NRedisStack.RedisStackCommands.SerializedCommand!
diff --git a/src/NRedisStack/ResponseParser.cs b/src/NRedisStack/ResponseParser.cs
@@ -516,7 +516,7 @@ public static CmsInformation
                 case "count":
                     count = (long)redisResults[i];
                     break;
-                case "cell size":
+                case "cell_size":
                     cellSize = (int)redisResults[i];
                     break;
             }

diff --git a/tests/NRedisStack.Tests/CountMinSketch/CmsTests.cs b/tests/NRedisStack.Tests/CountMinSketch/CmsTests.cs
@@ -39,6 +39,48 @@ public async Task TestInitByDimAsync(string endpointId)
         Assert.Equal(0, info.Count);
     }
 
+    [SkipIfRedisTheory(Comparison.LessThan, "8.12.0")]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public void TestInitByDimCellSize(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        cms.InitByDim(key, 16, 4, cellSize: 1);
+        var info = cms.Info(key);
+
+        Assert.Equal(16, info.Width);
+        Assert.Equal(4, info.Depth);
+        Assert.Equal(0, info.Count);
+        Assert.Equal(1, info.CellSize);
+    }
+
+    [SkipIfRedisTheory(Comparison.LessThan, "8.12.0")]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public async Task TestInitByDimCellSizeAsync(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        await cms.InitByDimAsync(key, 16, 4, cellSize: 8);
+        var info = await cms.InfoAsync(key);
+
+        Assert.Equal(16, info.Width);
+        Assert.Equal(4, info.Depth);
+        Assert.Equal(0, info.Count);
+        Assert.Equal(8, info.CellSize);
+    }
+
+    [Theory]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public void TestInitByDimInvalidCellSize(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        Assert.Throws<ArgumentOutOfRangeException>(() => cms.InitByDim(key, 16, 4, cellSize: 3));
+    }
+
     [Theory]
     [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
     public void TestInitByProb(string endpointId)
@@ -54,6 +96,22 @@ public void TestInitByProb(string endpointId)
         Assert.Equal(0, info.Count);
     }
 
+    [SkipIfRedisTheory(Comparison.LessThan, "8.12.0")]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public void TestInitByProbCellSize(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        cms.InitByProb(key, 0.01, 0.01, cellSize: 2);
+        var info = cms.Info(key);
+
+        Assert.Equal(200, info.Width);
+        Assert.Equal(7, info.Depth);
+        Assert.Equal(0, info.Count);
+        Assert.Equal(2, info.CellSize);
+    }
+
     [Theory]
     [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
     public async Task TestInitByProbAsync(string endpointId)
@@ -127,6 +185,38 @@ public async Task TestIncrByAsync(string endpointId)
 
     }
 
+    [SkipIfRedisTheory(Comparison.LessThan, "8.12.0")]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public void TestIncrByNegative(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        cms.InitByDim(key, 1000, 5);
+        cms.IncrBy(key, "foo", 10);
+        var resp = cms.IncrBy(key, "foo", -4);
+        Assert.Equal(6, resp);
+
+        var info = cms.Info(key);
+        Assert.Equal(6, info.Count);
+    }
+
+    [SkipIfRedisTheory(Comparison.LessThan, "8.12.0")]
+    [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
+    public async Task TestIncrByNegativeAsync(string endpointId)
+    {
+        var db = GetCleanDatabase(endpointId);
+        var cms = db.CMS();
+
+        await cms.InitByDimAsync(key, 1000, 5);
+        await cms.IncrByAsync(key, "foo", 10);
+        var resp = await cms.IncrByAsync(key, "foo", -4);
+        Assert.Equal(6, resp);
+
+        var info = await cms.InfoAsync(key);
+        Assert.Equal(6, info.Count);
+    }
+
     [Theory]
     [MemberData(nameof(EndpointsFixture.Env.AllEnvironments), MemberType = typeof(EndpointsFixture.Env))]
     public void TestIncrByMultipleArgs(string endpointId)

diff --git a/tests/dockers/.env.v8.12 b/tests/dockers/.env.v8.12
@@ -0,0 +1,7 @@
+# Environment variables for Redis 8.12
+# Used by the run-tests GitHub Action
+
+# No official 8.12 release image exists yet, so this is pinned to an unstable
+# preview build. Unlike the other .env.v* files, this tag is not guaranteed to
+# stay available - replace with the real release image once 8.12 ships.
+CLIENT_LIBS_TEST_IMAGE=redislabs/client-libs-test:unstable-34786335206-debian