oleg (0) /storage/work/trunk$ svn diff include/
Index: include/query/Aggregate.h
===================================================================
--- include/query/Aggregate.h	(revision 5176)
+++ include/query/Aggregate.h	(working copy)
@@ -132,7 +132,18 @@
         }
     }

-    virtual void merge(Value& dstState, Value const& srcState)  = 0;
+    virtual void merge(Value& dstState, Value const& srcState)
+    {
+        if (srcState.isNull()) {
+            return;
+        }
+        if (dstState.isNull()) {
+            dstState = srcState;
+        } else {
+            mergeNotNull(dstState, srcState);
+        }
+    }
+    virtual void mergeNotNull(Value& dstState, Value const& srcState) = 0;
     virtual void finalResult(Value& result, Value const& state) = 0;
 };

@@ -200,7 +211,7 @@
         }
     }

-    void merge(Value& dstState, Value const& srcState)
+    void mergeNotNull(Value& dstState, Value const& srcState)
     {
         A<T, TR>::merge(*static_cast< typename A<T, TR>::State* >(dstState.data()), *static_cast< typename A<T, TR>::State* >(srcState.data()));
     }
@@ -293,7 +304,7 @@
         }
     }

-    void merge(Value& dstState, Value const& srcState)
+    void mergeNotNull(Value& dstState, Value const& srcState)
     {
         A<T, TR>::merge(*static_cast< typename A<T, TR>::State* >(dstState.data()), *static_cast< typename A<T, TR>::State* >(srcState.data()));
     }
oleg (0) /storage/work/trunk$ svn diff src
Index: src/query/ops/aggregates/Aggregator.h
===================================================================
--- src/query/ops/aggregates/Aggregator.h	(revision 5176)
+++ src/query/ops/aggregates/Aggregator.h	(working copy)
@@ -485,7 +485,7 @@
         {
             setOutputPosition(stateArrayIterator, stateChunkIterator, bucket.first, i);
             Value& state = stateChunkIterator->getItem();
-            if (state.getMissingReason()==0)
+            if (state.getMissingReason() >= 0)
             {
                 _aggs[i]->initializeState(state);
             }
@@ -505,7 +505,7 @@
             setOutputPosition(stateArrayIterator, stateChunkIterator, bucket.first, i);
             Value& state = stateChunkIterator->getItem();
             const RLEPayload* payload = bucket.second.getPayload();
-            if (state.getMissingReason()==0)
+            if (state.getMissingReason() >= 0)
             {
                 _aggs[i]->initializeState(state);
             }
Index: src/array/Array.cpp
===================================================================
--- src/array/Array.cpp	(revision 5176)
+++ src/array/Array.cpp	(working copy)
@@ -395,11 +395,7 @@
                     if (!dstIterator->setPosition(srcIterator->getPosition()))
                         throw SYSTEM_EXCEPTION(SCIDB_SE_MERGE, SCIDB_LE_OPERATION_FAILED) << "setPosition";
                     Value& val2 = dstIterator->getItem();
-                    if (!val2.isNull())
-                    {
-                        aggregate->merge(val, val2);
-
-                    }
+                    aggregate->merge(val, val2);
                     dstIterator->writeItem(val);
                 }
                 ++(*srcIterator);
@@ -471,10 +467,7 @@
                     if (!dstIterator->setPosition(cpos))
                         throw SYSTEM_EXCEPTION(SCIDB_SE_MERGE, SCIDB_LE_OPERATION_FAILED) << "setPosition";
                     Value& val2 = dstIterator->getItem();
-                    if (!val2.isNull())
-                    {
-                        aggregate->merge(val, val2);
-                    }
+                    aggregate->merge(val, val2);
                     dstIterator->writeItem(val);
                     ++inputIter;
                 }