Fix Vector Set Index key corruption

libs/server/Resp/Vector/VectorManager.cs

@@ -40,8 +40,8 @@ public sealed partial class VectorManager : IDisposable
 
         internal const int IndexSizeBytes = Index.Size;
         internal const long VADDAppendLogArg = long.MinValue;
-        internal const long DeleteAfterDropArg = VADDAppendLogArg + 1;
-        internal const long RecreateIndexArg = DeleteAfterDropArg + 1;
+        // DeleteAfterDropArg used to be here
+        internal const long RecreateIndexArg = VADDAppendLogArg + 2;
         internal const long VREMAppendLogArg = RecreateIndexArg + 1;
         internal const long MigrateElementKeyLogArg = VREMAppendLogArg + 1;
         internal const long MigrateIndexKeyLogArg = MigrateElementKeyLogArg + 1;

libs/server/Storage/Functions/MainStore/RMWMethods.cs

@@ -812,20 +812,15 @@ private readonly IPUResult InPlaceUpdaterWorker(ref LogRecord logRecord, ref Str
                 case RespCommand.VADD:
                     // Adding to an existing VectorSet is modeled as a read operations
                     //
-                    // However, we do synthesize some (pointless) writes to implement replication
-                    // and a "make me delete=able"-update during drop.
+                    // However, we do synthesize some (pointless) writes to implement replication (which we ignore here).
                     //
                     // Another "not quite write" is the recreate an index write operation
                     // that occurs if we're adding to an index that was restored from disk 
                     // or a primary node.
 
-                    // Handle "make me delete-able"
-                    if (input.arg1 == VectorManager.DeleteAfterDropArg)
-                    {
-                        logRecord.ValueSpan.Clear();
-                    }
-                    else if (input.arg1 == VectorManager.RecreateIndexArg)
+                    if (input.arg1 == VectorManager.RecreateIndexArg)
                     {
+                        // Recreate index
                         var newIndexPtr = MemoryMarshal.Read<nint>(input.parseState.GetArgSliceByRef(11).Span);
 
                         functionsState.vectorManager.RecreateIndex(newIndexPtr, logRecord.ValueSpan);
@@ -1327,19 +1322,20 @@ public readonly bool CopyUpdater<TSourceLogRecord>(in TSourceLogRecord srcLogRec
                     break;
 
                 case RespCommand.VADD:
-                    // Handle "make me delete-able"
-                    if (input.arg1 == VectorManager.DeleteAfterDropArg)
-                    {
-                        dstLogRecord.ValueSpan.Clear();
-                    }
-                    else if (input.arg1 == VectorManager.RecreateIndexArg)
+                    if (input.arg1 == VectorManager.RecreateIndexArg)
                     {
+                        // Recreate index
                         var newIndexPtr = MemoryMarshal.Read<nint>(input.parseState.GetArgSliceByRef(11).Span);
 
                         oldValue.CopyTo(dstLogRecord.ValueSpan);
 
                         functionsState.vectorManager.RecreateIndex(newIndexPtr, dstLogRecord.ValueSpan);
                     }
+                    else if (input.arg1 is VectorManager.VADDAppendLogArg or VectorManager.VREMAppendLogArg)
+                    {
+                        // VADD has triggered a CU of the index key - we want to do nothing but we have to copy to prevent corruption
+                        oldValue.CopyTo(dstLogRecord.ValueSpan);
+                    }
 
                     break;
 

libs/server/Storage/Functions/MainStore/VarLenInputMethods.cs

@@ -361,6 +361,12 @@ public RecordFieldInfo GetRMWModifiedFieldInfo<TSourceLogRecord>(in TSourceLogRe
 
                     case RespCommand.VADD:
                     case RespCommand.VREM:
+                        if (input.arg1 is VectorManager.VADDAppendLogArg or VectorManager.VREMAppendLogArg)
+                        {
+                            // During replication we might trigger a CU, in which case... make sure there's space for the index we'll copy over
+                            fieldInfo.ValueSize = VectorManager.IndexSize;
+                        }
+
                         return fieldInfo;
 
                     default: