0 4 4

src/TidesDB/ColumnFamily.cs

@@ -182,6 +182,21 @@ public double RangeCost(ReadOnlySpan<byte> keyA, ReadOnlySpan<byte> keyB)
         return cost;
     }
 
+    /// <summary>
+    /// Updates runtime-safe configuration settings for this column family.
+    /// Changes apply to new operations only. Existing SSTables and memtables
+    /// retain their original settings.
+    /// </summary>
+    /// <param name="config">The new column family configuration.</param>
+    /// <param name="persistToDisk">If true, saves changes to config.ini on disk.</param>
+    public void UpdateRuntimeConfig(ColumnFamilyConfig config, bool persistToDisk = true)
+    {
+        var nativeConfig = TidesDb.CreateNativeColumnFamilyConfigPublic(config);
+        var result = NativeMethods.tidesdb_cf_update_runtime_config(
+            Handle, ref nativeConfig, persistToDisk ? 1 : 0);
+        TidesDBException.ThrowIfError(result, "failed to update runtime config");
+    }
+
     /// <summary>
     /// Gets statistics about this column family.
     /// </summary>

src/TidesDB/Config.cs

@@ -51,6 +51,11 @@ public sealed class Config
     /// </summary>
     public ulong MaxOpenSstables { get; init; } = 256;
 
+    /// <summary>
+    /// Global memory limit in bytes (default: 0 = auto, 50% of system RAM; minimum: 5% of system RAM).
+    /// </summary>
+    public ulong MaxMemoryUsage { get; init; } = 0;
+
     /// <summary>
     /// Flag to determine if debug logging should be written to a file (default: false).
     /// </summary>

src/TidesDB/Native/NativeMethods.cs

@@ -165,6 +165,14 @@ internal static partial class NativeMethods
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_cf_set_commit_hook")]
     internal static partial int tidesdb_cf_set_commit_hook(nint cf, nint fn, nint ctx);
 
+    // Runtime config update
+    [LibraryImport(LibraryName, EntryPoint = "tidesdb_cf_update_runtime_config")]
+    internal static partial int tidesdb_cf_update_runtime_config(nint cf, ref NativeColumnFamilyConfig config, int persistToDisk);
+
+    // Get comparator
+    [LibraryImport(LibraryName, EntryPoint = "tidesdb_get_comparator", StringMarshalling = StringMarshalling.Utf8)]
+    internal static partial int tidesdb_get_comparator(nint db, string name, out nint fn, out nint ctx);
+
     // Range cost estimation
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_range_cost")]
     internal static unsafe partial int tidesdb_range_cost(nint cf, byte* keyA, nuint keyASize, byte* keyB, nuint keyBSize, out double cost);

src/TidesDB/Native/NativeStructs.cs

@@ -27,6 +27,7 @@ internal struct NativeConfig
     public int LogLevel;
     public nuint BlockCacheSize;
     public nuint MaxOpenSstables;
+    public nuint MaxMemoryUsage;
     public int LogToFile;
     public nuint LogTruncationAt;
 }

src/TidesDB/TidesDB.cs

@@ -52,6 +52,7 @@ public static TidesDb Open(Config config)
             LogLevel = (int)config.LogLevel,
             BlockCacheSize = (nuint)config.BlockCacheSize,
             MaxOpenSstables = (nuint)config.MaxOpenSstables,
+            MaxMemoryUsage = (nuint)config.MaxMemoryUsage,
             LogToFile = config.LogToFile ? 1 : 0,
             LogTruncationAt = (nuint)config.LogTruncationAt
         };
@@ -214,6 +215,19 @@ public void RegisterComparator(string name, string? ctxStr = null)
         TidesDBException.ThrowIfError(result, "failed to register comparator");
     }
 
+    /// <summary>
+    /// Retrieves a previously registered comparator by name.
+    /// Returns true if the comparator is registered, false otherwise.
+    /// </summary>
+    /// <param name="name">The comparator name.</param>
+    /// <returns>True if the comparator is registered.</returns>
+    public bool GetComparator(string name)
+    {
+        ThrowIfDisposed();
+        var result = NativeMethods.tidesdb_get_comparator(_handle, name, out _, out _);
+        return result == 0;
+    }
+
     /// <summary>
     /// Gets statistics about the block cache.
     /// </summary>
@@ -237,6 +251,9 @@ public CacheStats GetCacheStats()
         };
     }
 
+    internal static unsafe NativeColumnFamilyConfig CreateNativeColumnFamilyConfigPublic(ColumnFamilyConfig config)
+        => CreateNativeColumnFamilyConfig(config);
+
     private static unsafe NativeColumnFamilyConfig CreateNativeColumnFamilyConfig(ColumnFamilyConfig config)
     {
         var nativeConfig = new NativeColumnFamilyConfig

src/TidesDB/TidesDB.csproj

@@ -9,7 +9,7 @@
 
     <!-- Package metadata -->
     <PackageId>TidesDB</PackageId>
-    <Version>0.4.3</Version>
+    <Version>0.4.4</Version>
     <Authors>TidesDB</Authors>
     <Company>TidesDB</Company>
     <Description>Official C# bindings for TidesDB - A high-performance embedded key-value storage engine</Description>

tests/TidesDB.Tests/TidesDBTests.cs

@@ -852,4 +852,73 @@ public void RangeCost_ReversedKeys_ShouldReturnSameResult()
 
         Assert.Equal(costAB, costBA);
     }
+
+    [Fact]
+    public void UpdateRuntimeConfig_ShouldSucceed()
+    {
+        using var db = OpenDatabase();
+        db.CreateColumnFamily("test_cf");
+        var cf = db.GetColumnFamily("test_cf")!;
+
+        var newConfig = new ColumnFamilyConfig
+        {
+            WriteBufferSize = 128 * 1024 * 1024,
+            BloomFpr = 0.001,
+            CompressionAlgorithm = CompressionAlgorithm.Zstd,
+        };
+
+        cf.UpdateRuntimeConfig(newConfig);
+    }
+
+    [Fact]
+    public void UpdateRuntimeConfig_WithoutPersist_ShouldSucceed()
+    {
+        using var db = OpenDatabase();
+        db.CreateColumnFamily("test_cf");
+        var cf = db.GetColumnFamily("test_cf")!;
+
+        var newConfig = new ColumnFamilyConfig
+        {
+            WriteBufferSize = 256 * 1024 * 1024,
+        };
+
+        cf.UpdateRuntimeConfig(newConfig, persistToDisk: false);
+    }
+
+    [Fact]
+    public void GetComparator_BuiltIn_ShouldReturnTrue()
+    {
+        using var db = OpenDatabase();
+
+        Assert.True(db.GetComparator("memcmp"));
+        Assert.True(db.GetComparator("reverse"));
+    }
+
+    [Fact]
+    public void GetComparator_NonExistent_ShouldReturnFalse()
+    {
+        using var db = OpenDatabase();
+
+        Assert.False(db.GetComparator("nonexistent_comparator"));
+    }
+
+    [Fact]
+    public void ReleaseSavepoint_ShouldSucceed()
+    {
+        using var db = OpenDatabase();
+        db.CreateColumnFamily("test_cf");
+        var cf = db.GetColumnFamily("test_cf")!;
+
+        using var txn = db.BeginTransaction();
+
+        txn.Put(cf, Encoding.UTF8.GetBytes("key1"), Encoding.UTF8.GetBytes("value1"));
+        txn.Savepoint("sp1");
+        txn.Put(cf, Encoding.UTF8.GetBytes("key2"), Encoding.UTF8.GetBytes("value2"));
+        txn.ReleaseSavepoint("sp1");
+        txn.Commit();
+
+        using var readTxn = db.BeginTransaction();
+        Assert.NotNull(readTxn.Get(cf, Encoding.UTF8.GetBytes("key1")));
+        Assert.NotNull(readTxn.Get(cf, Encoding.UTF8.GetBytes("key2")));
+    }
 }