correct native struct layout to match db.h; add unified memtable conf…

src/TidesDB/Config.cs

@@ -66,6 +66,36 @@ public sealed class Config
     /// </summary>
     public ulong LogTruncationAt { get; init; } = 0;
 
+    /// <summary>
+    /// Enable unified memtable mode (default: false = per-CF memtables).
+    /// </summary>
+    public bool UnifiedMemtable { get; init; } = false;
+
+    /// <summary>
+    /// Unified memtable write buffer size in bytes (default: 0 = auto).
+    /// </summary>
+    public ulong UnifiedMemtableWriteBufferSize { get; init; } = 0;
+
+    /// <summary>
+    /// Skip list max level for unified memtable (default: 0 = 12).
+    /// </summary>
+    public int UnifiedMemtableSkipListMaxLevel { get; init; } = 0;
+
+    /// <summary>
+    /// Skip list probability for unified memtable (default: 0 = 0.25).
+    /// </summary>
+    public float UnifiedMemtableSkipListProbability { get; init; } = 0;
+
+    /// <summary>
+    /// Sync mode for unified WAL (default: None).
+    /// </summary>
+    public SyncMode UnifiedMemtableSyncMode { get; init; } = SyncMode.None;
+
+    /// <summary>
+    /// Sync interval for unified WAL in microseconds (default: 0).
+    /// </summary>
+    public ulong UnifiedMemtableSyncIntervalUs { get; init; } = 0;
+
     /// <summary>
     /// Creates a default configuration with the specified database path.
     /// </summary>
@@ -185,6 +215,21 @@ public sealed class ColumnFamilyConfig
     /// </summary>
     public bool UseBtree { get; init; } = false;
 
+    /// <summary>
+    /// Target SSTable size in object store mode in bytes (default: 0 = auto/256MB).
+    /// </summary>
+    public ulong ObjectTargetFileSize { get; init; } = 0;
+
+    /// <summary>
+    /// Compact less aggressively in object store mode (default: false).
+    /// </summary>
+    public bool ObjectLazyCompaction { get; init; } = false;
+
+    /// <summary>
+    /// Download all inputs before merge in object store mode (default: true).
+    /// </summary>
+    public bool ObjectPrefetchCompaction { get; init; } = true;
+
     /// <summary>
     /// Creates a default column family configuration.
     /// </summary>

src/TidesDB/Enums.cs

@@ -80,5 +80,6 @@ public enum ErrorCode
     MemoryLimit = -9,
     InvalidDb = -10,
     Unknown = -11,
-    Locked = -12
+    Locked = -12,
+    Readonly = -13
 }

src/TidesDB/Iterator.cs

@@ -135,6 +135,26 @@ public byte[] Key()
         return key;
     }
 
+    /// <summary>
+    /// Gets both the current key and value in a single call.
+    /// More efficient than calling Key() and Value() separately.
+    /// </summary>
+    public (byte[] Key, byte[] Value) KeyValue()
+    {
+        ThrowIfDisposed();
+        var result = NativeMethods.tidesdb_iter_key_value(
+            _handle, out var keyPtr, out var keySize, out var valuePtr, out var valueSize);
+        TidesDBException.ThrowIfError(result, "failed to get key-value pair");
+
+        var key = new byte[(int)keySize];
+        Marshal.Copy(keyPtr, key, 0, (int)keySize);
+
+        var value = new byte[(int)valueSize];
+        Marshal.Copy(valuePtr, value, 0, (int)valueSize);
+
+        return (key, value);
+    }
+
     /// <summary>
     /// Gets the current value.
     /// </summary>

src/TidesDB/Native/NativeMethods.cs

@@ -108,13 +108,20 @@ internal static partial class NativeMethods
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_iter_value")]
     internal static partial int tidesdb_iter_value(nint iter, out nint value, out nuint valueSize);
 
+    [LibraryImport(LibraryName, EntryPoint = "tidesdb_iter_key_value")]
+    internal static partial int tidesdb_iter_key_value(nint iter, out nint key, out nuint keySize, out nint value, out nuint valueSize);
+
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_iter_free")]
     internal static partial void tidesdb_iter_free(nint iter);
 
     // Transaction reset
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_txn_reset")]
     internal static partial int tidesdb_txn_reset(nint txn, int isolation);
 
+    // Column family delete by pointer
+    [LibraryImport(LibraryName, EntryPoint = "tidesdb_delete_column_family")]
+    internal static partial int tidesdb_delete_column_family(nint db, nint cf);
+
     // Column family clone/rename operations
     [LibraryImport(LibraryName, EntryPoint = "tidesdb_clone_column_family", StringMarshalling = StringMarshalling.Utf8)]
     internal static partial int tidesdb_clone_column_family(nint db, string sourceName, string destName);

src/TidesDB/Native/NativeStructs.cs

@@ -27,9 +27,17 @@ internal struct NativeConfig
     public int LogLevel;
     public nuint BlockCacheSize;
     public nuint MaxOpenSstables;
-    public nuint MaxMemoryUsage;
     public int LogToFile;
     public nuint LogTruncationAt;
+    public nuint MaxMemoryUsage;
+    public int UnifiedMemtable;
+    public nuint UnifiedMemtableWriteBufferSize;
+    public int UnifiedMemtableSkipListMaxLevel;
+    public float UnifiedMemtableSkipListProbability;
+    public int UnifiedMemtableSyncMode;
+    public ulong UnifiedMemtableSyncIntervalUs;
+    public nint ObjectStore;
+    public nint ObjectStoreConfig;
 }
 
 [StructLayout(LayoutKind.Sequential)]
@@ -62,6 +70,9 @@ internal unsafe struct NativeColumnFamilyConfig
     public int UseBtree;
     public nint CommitHookFn;
     public nint CommitHookCtx;
+    public nuint ObjectTargetFileSize;
+    public int ObjectLazyCompaction;
+    public int ObjectPrefetchCompaction;
 }
 
 [StructLayout(LayoutKind.Sequential)]
@@ -82,12 +93,12 @@ internal struct NativeStats
     public nuint MemtableSize;
     public nint LevelSizes;
     public nint LevelNumSstables;
-    public nint LevelKeyCounts;
     public nint Config;
     public ulong TotalKeys;
     public ulong TotalDataSize;
     public double AvgKeySize;
     public double AvgValueSize;
+    public nint LevelKeyCounts;
     public double ReadAmp;
     public double HitRate;
     public int UseBtree;
@@ -126,4 +137,20 @@ internal struct NativeDbStats
     public long TxnMemoryBytes;
     public nuint CompactionQueueSize;
     public nuint FlushQueueSize;
+    public int UnifiedMemtableEnabled;
+    public long UnifiedMemtableBytes;
+    public int UnifiedImmutableCount;
+    public int UnifiedIsFlushing;
+    public uint UnifiedNextCfIndex;
+    public ulong UnifiedWalGeneration;
+    public int ObjectStoreEnabled;
+    public nint ObjectStoreConnector;
+    public nuint LocalCacheBytesUsed;
+    public nuint LocalCacheBytesMax;
+    public int LocalCacheNumFiles;
+    public ulong LastUploadedGeneration;
+    public nuint UploadQueueDepth;
+    public ulong TotalUploads;
+    public ulong TotalUploadFailures;
+    public int ReplicaMode;
 }

src/TidesDB/Stats.cs

@@ -181,6 +181,86 @@ public sealed class DbStats
     /// Number of pending flush tasks in queue.
     /// </summary>
     public ulong FlushQueueSize { get; init; }
+
+    /// <summary>
+    /// Whether unified memtable mode is active.
+    /// </summary>
+    public bool UnifiedMemtableEnabled { get; init; }
+
+    /// <summary>
+    /// Bytes in unified active memtable.
+    /// </summary>
+    public long UnifiedMemtableBytes { get; init; }
+
+    /// <summary>
+    /// Number of unified immutable memtables.
+    /// </summary>
+    public int UnifiedImmutableCount { get; init; }
+
+    /// <summary>
+    /// Whether unified memtable is currently flushing/rotating.
+    /// </summary>
+    public bool UnifiedIsFlushing { get; init; }
+
+    /// <summary>
+    /// Next CF index to be assigned in unified mode.
+    /// </summary>
+    public uint UnifiedNextCfIndex { get; init; }
+
+    /// <summary>
+    /// Current unified WAL generation counter.
+    /// </summary>
+    public ulong UnifiedWalGeneration { get; init; }
+
+    /// <summary>
+    /// Whether object store mode is active.
+    /// </summary>
+    public bool ObjectStoreEnabled { get; init; }
+
+    /// <summary>
+    /// Connector name ("s3", "gcs", "fs", etc.), or null if not using object store.
+    /// </summary>
+    public string? ObjectStoreConnector { get; init; }
+
+    /// <summary>
+    /// Current local file cache usage in bytes.
+    /// </summary>
+    public ulong LocalCacheBytesUsed { get; init; }
+
+    /// <summary>
+    /// Configured maximum local cache size in bytes.
+    /// </summary>
+    public ulong LocalCacheBytesMax { get; init; }
+
+    /// <summary>
+    /// Number of files tracked in local cache.
+    /// </summary>
+    public int LocalCacheNumFiles { get; init; }
+
+    /// <summary>
+    /// Highest WAL generation confirmed uploaded.
+    /// </summary>
+    public ulong LastUploadedGeneration { get; init; }
+
+    /// <summary>
+    /// Number of pending upload jobs in the queue.
+    /// </summary>
+    public ulong UploadQueueDepth { get; init; }
+
+    /// <summary>
+    /// Lifetime count of objects uploaded to object store.
+    /// </summary>
+    public ulong TotalUploads { get; init; }
+
+    /// <summary>
+    /// Lifetime count of permanently failed uploads (after all retries).
+    /// </summary>
+    public ulong TotalUploadFailures { get; init; }
+
+    /// <summary>
+    /// Whether running in read-only replica mode.
+    /// </summary>
+    public bool ReplicaMode { get; init; }
 }
 
 /// <summary>

src/TidesDB/TidesDB.cs

@@ -52,9 +52,17 @@ 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
+            LogTruncationAt = (nuint)config.LogTruncationAt,
+            MaxMemoryUsage = (nuint)config.MaxMemoryUsage,
+            UnifiedMemtable = config.UnifiedMemtable ? 1 : 0,
+            UnifiedMemtableWriteBufferSize = (nuint)config.UnifiedMemtableWriteBufferSize,
+            UnifiedMemtableSkipListMaxLevel = config.UnifiedMemtableSkipListMaxLevel,
+            UnifiedMemtableSkipListProbability = config.UnifiedMemtableSkipListProbability,
+            UnifiedMemtableSyncMode = (int)config.UnifiedMemtableSyncMode,
+            UnifiedMemtableSyncIntervalUs = config.UnifiedMemtableSyncIntervalUs,
+            ObjectStore = nint.Zero,
+            ObjectStoreConfig = nint.Zero
         };
 
         var result = NativeMethods.tidesdb_open(ref nativeConfig, out var dbHandle);
@@ -93,6 +101,18 @@ public void DropColumnFamily(string name)
         TidesDBException.ThrowIfError(result, "failed to drop column family");
     }
 
+    /// <summary>
+    /// Deletes a column family by pointer. Faster than DropColumnFamily when you already
+    /// hold a ColumnFamily handle, as it skips the name lookup.
+    /// </summary>
+    /// <param name="cf">The column family to delete.</param>
+    public void DeleteColumnFamily(ColumnFamily cf)
+    {
+        ThrowIfDisposed();
+        var result = NativeMethods.tidesdb_delete_column_family(_handle, cf.Handle);
+        TidesDBException.ThrowIfError(result, "failed to delete column family");
+    }
+
     /// <summary>
     /// Clones a column family, creating a complete copy with a new name.
     /// </summary>
@@ -266,7 +286,24 @@ public DbStats GetDbStats()
             GlobalSeq = nativeStats.GlobalSeq,
             TxnMemoryBytes = nativeStats.TxnMemoryBytes,
             CompactionQueueSize = (ulong)nativeStats.CompactionQueueSize,
-            FlushQueueSize = (ulong)nativeStats.FlushQueueSize
+            FlushQueueSize = (ulong)nativeStats.FlushQueueSize,
+            UnifiedMemtableEnabled = nativeStats.UnifiedMemtableEnabled != 0,
+            UnifiedMemtableBytes = nativeStats.UnifiedMemtableBytes,
+            UnifiedImmutableCount = nativeStats.UnifiedImmutableCount,
+            UnifiedIsFlushing = nativeStats.UnifiedIsFlushing != 0,
+            UnifiedNextCfIndex = nativeStats.UnifiedNextCfIndex,
+            UnifiedWalGeneration = nativeStats.UnifiedWalGeneration,
+            ObjectStoreEnabled = nativeStats.ObjectStoreEnabled != 0,
+            ObjectStoreConnector = nativeStats.ObjectStoreConnector != nint.Zero
+                ? Marshal.PtrToStringAnsi(nativeStats.ObjectStoreConnector) : null,
+            LocalCacheBytesUsed = (ulong)nativeStats.LocalCacheBytesUsed,
+            LocalCacheBytesMax = (ulong)nativeStats.LocalCacheBytesMax,
+            LocalCacheNumFiles = nativeStats.LocalCacheNumFiles,
+            LastUploadedGeneration = nativeStats.LastUploadedGeneration,
+            UploadQueueDepth = (ulong)nativeStats.UploadQueueDepth,
+            TotalUploads = nativeStats.TotalUploads,
+            TotalUploadFailures = nativeStats.TotalUploadFailures,
+            ReplicaMode = nativeStats.ReplicaMode != 0
         };
     }
 
@@ -322,6 +359,9 @@ private static unsafe NativeColumnFamilyConfig CreateNativeColumnFamilyConfig(Co
             UseBtree = config.UseBtree ? 1 : 0,
             CommitHookFn = nint.Zero,
             CommitHookCtx = nint.Zero,
+            ObjectTargetFileSize = (nuint)config.ObjectTargetFileSize,
+            ObjectLazyCompaction = config.ObjectLazyCompaction ? 1 : 0,
+            ObjectPrefetchCompaction = config.ObjectPrefetchCompaction ? 1 : 0,
             ComparatorFnCached = nint.Zero,
             ComparatorCtxCached = nint.Zero
         };

src/TidesDB/TidesDB.csproj

@@ -9,7 +9,7 @@
 
     <!-- Package metadata -->
     <PackageId>TidesDB</PackageId>
-    <Version>0.4.5</Version>
+    <Version>0.4.6</Version>
     <Authors>TidesDB</Authors>
     <Company>TidesDB</Company>
     <Description>Official C# bindings for TidesDB - A high-performance embedded key-value storage engine</Description>

src/TidesDB/TidesDBException.cs

@@ -53,6 +53,7 @@ private static string FormatMessage(ErrorCode errorCode, string? context)
             ErrorCode.MemoryLimit => "memory limit exceeded",
             ErrorCode.InvalidDb => "invalid database handle",
             ErrorCode.Locked => "database is locked",
+            ErrorCode.Readonly => "database is read-only",
             _ => "unknown error"
         };