diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp
new file mode 100644
index 0000000..932661c9
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * Test that scalar sum() produces correct output type
+ */
+
+select array_sum(array_reverse(lst))
+let lst = (
+  from range(1, 3) r
+  select value int32(to_string(r))
+)
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp
new file mode 100644
index 0000000..361a59b
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/aggregate/sum/scalar_sum_type/scalar_sum_type.1.query.sqlpp
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * Test that scalar sum() produces correct output type
+ */
+
+select strict_sum(array_reverse(lst))
+let lst = (
+  from range(1, 3) r
+  select value int32(to_string(r))
+)
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.adm
new file mode 100644
index 0000000..d9b1127
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate-sql/sum/scalar_sum_type/scalar_sum_type.1.adm
@@ -0,0 +1 @@
+{ "$1": 6 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate/sum/scalar_sum_type/scalar_sum_type.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate/sum/scalar_sum_type/scalar_sum_type.1.adm
new file mode 100644
index 0000000..d9b1127
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/aggregate/sum/scalar_sum_type/scalar_sum_type.1.adm
@@ -0,0 +1 @@
+{ "$1": 6 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
index f8164e8..0c3b15b 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -834,6 +834,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="aggregate">
+      <compilation-unit name="sum/scalar_sum_type">
+        <output-dir compare="Text">sum/scalar_sum_type</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="aggregate">
       <compilation-unit name="scalar_var">
         <output-dir compare="Text">scalar_var</output-dir>
       </compilation-unit>
@@ -2097,6 +2102,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="aggregate-sql">
+      <compilation-unit name="sum/scalar_sum_type">
+        <output-dir compare="Text">sum/scalar_sum_type</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="aggregate-sql">
       <compilation-unit name="scalar_var">
         <output-dir compare="Text">scalar_var</output-dir>
       </compilation-unit>
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
index 268c1f6..63573a1 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
@@ -1832,6 +1832,11 @@
         addFunction(NEGINF_IF, DoubleIfTypeComputer.INSTANCE, true);
 
         // Aggregate Functions
+        ScalarVersionOfAggregateResultType scalarNumericSumTypeComputer =
+                new ScalarVersionOfAggregateResultType(NumericSumAggTypeComputer.INSTANCE);
+        ScalarVersionOfAggregateResultType scalarMinMaxTypeComputer =
+                new ScalarVersionOfAggregateResultType(MinMaxAggTypeComputer.INSTANCE);
+
         addPrivateFunction(LISTIFY, OrderedListConstructorTypeComputer.INSTANCE, true);
         addFunction(SCALAR_ARRAYAGG, ScalarArrayAggTypeComputer.INSTANCE, true);
         addFunction(MAX, MinMaxAggTypeComputer.INSTANCE, true);
@@ -1877,7 +1882,7 @@
 
         // SUM
         addFunction(SUM, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SUM, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SUM, scalarNumericSumTypeComputer, true);
         addPrivateFunction(LOCAL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
         addPrivateFunction(INTERMEDIATE_SUM, NumericSumAggTypeComputer.INSTANCE, true);
         addPrivateFunction(GLOBAL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
@@ -1893,8 +1898,8 @@
         addPrivateFunction(SERIAL_INTERMEDIATE_SQL_AVG, LocalAvgTypeComputer.INSTANCE, true);
         addFunction(SCALAR_AVG, NullableDoubleTypeComputer.INSTANCE, true);
         addFunction(SCALAR_COUNT, AInt64TypeComputer.INSTANCE, true);
-        addFunction(SCALAR_MAX, ScalarVersionOfAggregateResultType.INSTANCE, true);
-        addFunction(SCALAR_MIN, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_MAX, scalarMinMaxTypeComputer, true);
+        addFunction(SCALAR_MIN, scalarMinMaxTypeComputer, true);
         addPrivateFunction(INTERMEDIATE_AVG, LocalAvgTypeComputer.INSTANCE, true);
         addFunction(SCALAR_STDDEV_SAMP, NullableDoubleTypeComputer.INSTANCE, true);
         addPrivateFunction(INTERMEDIATE_STDDEV_SAMP, LocalSingleVarStatisticsTypeComputer.INSTANCE, true);
@@ -1935,7 +1940,7 @@
 
         // SQL SUM
         addFunction(SQL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_SUM, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SQL_SUM, scalarNumericSumTypeComputer, true);
         addPrivateFunction(LOCAL_SQL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
         addPrivateFunction(INTERMEDIATE_SQL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
         addPrivateFunction(GLOBAL_SQL_SUM, NumericSumAggTypeComputer.INSTANCE, true);
@@ -1959,8 +1964,8 @@
         addPrivateFunction(GLOBAL_SQL_MIN, MinMaxAggTypeComputer.INSTANCE, true);
         addFunction(SCALAR_SQL_AVG, NullableDoubleTypeComputer.INSTANCE, true);
         addFunction(SCALAR_SQL_COUNT, AInt64TypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_MAX, ScalarVersionOfAggregateResultType.INSTANCE, true);
-        addFunction(SCALAR_SQL_MIN, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SQL_MAX, scalarMinMaxTypeComputer, true);
+        addFunction(SCALAR_SQL_MIN, scalarMinMaxTypeComputer, true);
         addPrivateFunction(INTERMEDIATE_SQL_AVG, LocalAvgTypeComputer.INSTANCE, true);
         addFunction(SQL_STDDEV_SAMP, NullableDoubleTypeComputer.INSTANCE, true);
         addPrivateFunction(GLOBAL_SQL_STDDEV_SAMP, NullableDoubleTypeComputer.INSTANCE, true);
@@ -2035,9 +2040,9 @@
         addFunction(SCALAR_SQL_COUNT_DISTINCT, AInt64TypeComputer.INSTANCE, true);
 
         addFunction(SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SUM_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SUM_DISTINCT, scalarNumericSumTypeComputer, true);
         addFunction(SQL_SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_SUM_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SQL_SUM_DISTINCT, scalarNumericSumTypeComputer, true);
 
         addFunction(AVG_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
         addFunction(SCALAR_AVG_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
@@ -2045,14 +2050,14 @@
         addFunction(SCALAR_SQL_AVG_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
 
         addFunction(MAX_DISTINCT, MinMaxAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_MAX_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_MAX_DISTINCT, scalarMinMaxTypeComputer, true);
         addFunction(SQL_MAX_DISTINCT, MinMaxAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_MAX_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SQL_MAX_DISTINCT, scalarMinMaxTypeComputer, true);
 
         addFunction(MIN_DISTINCT, MinMaxAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_MIN_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_MIN_DISTINCT, scalarMinMaxTypeComputer, true);
         addFunction(SQL_MIN_DISTINCT, MinMaxAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_MIN_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
+        addFunction(SCALAR_SQL_MIN_DISTINCT, scalarMinMaxTypeComputer, true);
 
         addFunction(STDDEV_SAMP_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
         addFunction(SCALAR_STDDEV_SAMP_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/AggregateResultTypeComputer.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/AggregateResultTypeComputer.java
new file mode 100644
index 0000000..8e663a7
--- /dev/null
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/AggregateResultTypeComputer.java
@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.asterix.om.typecomputer.impl;
+
+import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
+import org.apache.asterix.om.types.IAType;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import org.apache.hyracks.api.exceptions.SourceLocation;
+
+public abstract class AggregateResultTypeComputer extends AbstractResultTypeComputer {
+    @Override
+    protected void checkArgType(FunctionIdentifier funcId, int argIndex, IAType type, SourceLocation sourceLoc)
+            throws AlgebricksException {
+        super.checkArgType(funcId, argIndex, type, sourceLoc);
+    }
+
+    @Override
+    protected abstract IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes)
+            throws AlgebricksException;
+}
\ No newline at end of file
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/MinMaxAggTypeComputer.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/MinMaxAggTypeComputer.java
index c34b5ed..fc1eee5 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/MinMaxAggTypeComputer.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/MinMaxAggTypeComputer.java
@@ -19,7 +19,6 @@
 package org.apache.asterix.om.typecomputer.impl;
 
 import org.apache.asterix.dataflow.data.common.ILogicalBinaryComparator;
-import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
 import org.apache.asterix.om.types.ATypeTag;
 import org.apache.asterix.om.types.AUnionType;
 import org.apache.asterix.om.types.BuiltinType;
@@ -27,7 +26,7 @@
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
 import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
 
-public class MinMaxAggTypeComputer extends AbstractResultTypeComputer {
+public class MinMaxAggTypeComputer extends AggregateResultTypeComputer {
 
     public static final MinMaxAggTypeComputer INSTANCE = new MinMaxAggTypeComputer();
 
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/NumericSumAggTypeComputer.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/NumericSumAggTypeComputer.java
index 1c67e56..a4b5e34 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/NumericSumAggTypeComputer.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/NumericSumAggTypeComputer.java
@@ -18,42 +18,20 @@
  */
 package org.apache.asterix.om.typecomputer.impl;
 
-import org.apache.asterix.om.exceptions.UnsupportedTypeException;
-import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
 import org.apache.asterix.om.types.ATypeTag;
 import org.apache.asterix.om.types.AUnionType;
 import org.apache.asterix.om.types.BuiltinType;
 import org.apache.asterix.om.types.IAType;
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
 import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
-import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
-import org.apache.hyracks.api.exceptions.SourceLocation;
 
-public class NumericSumAggTypeComputer extends AbstractResultTypeComputer {
+public class NumericSumAggTypeComputer extends AggregateResultTypeComputer {
     public static final NumericSumAggTypeComputer INSTANCE = new NumericSumAggTypeComputer();
 
     private NumericSumAggTypeComputer() {
     }
 
     @Override
-    protected void checkArgType(FunctionIdentifier funcId, int argIndex, IAType type, SourceLocation sourceLoc)
-            throws AlgebricksException {
-        ATypeTag tag = type.getTypeTag();
-        switch (tag) {
-            case DOUBLE:
-            case FLOAT:
-            case BIGINT:
-            case INTEGER:
-            case SMALLINT:
-            case TINYINT:
-            case ANY:
-                break;
-            default:
-                throw new UnsupportedTypeException(sourceLoc, funcId, tag);
-        }
-    }
-
-    @Override
     protected IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes) throws AlgebricksException {
         ATypeTag tag = strippedInputTypes[0].getTypeTag();
         switch (tag) {
@@ -61,15 +39,12 @@
             case SMALLINT:
             case INTEGER:
             case BIGINT:
-                IAType int64Type = BuiltinType.AINT64;
-                return AUnionType.createNullableType(int64Type, "AggResult");
+                return AUnionType.createNullableType(BuiltinType.AINT64);
             case FLOAT:
             case DOUBLE:
-                IAType doubleType = BuiltinType.ADOUBLE;
-                return AUnionType.createNullableType(doubleType, "AggResult");
+                return AUnionType.createNullableType(BuiltinType.ADOUBLE);
             case ANY:
-                IAType anyType = strippedInputTypes[0];
-                return AUnionType.createNullableType(anyType, "AggResult");
+                return BuiltinType.ANY;
             default:
                 // All other possible cases.
                 return BuiltinType.ANULL;
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/ScalarVersionOfAggregateResultType.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/ScalarVersionOfAggregateResultType.java
index 5b90974..fda0285 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/ScalarVersionOfAggregateResultType.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/ScalarVersionOfAggregateResultType.java
@@ -18,9 +18,7 @@
  */
 package org.apache.asterix.om.typecomputer.impl;
 
-import org.apache.asterix.om.exceptions.TypeMismatchException;
 import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
-import org.apache.asterix.om.types.ATypeTag;
 import org.apache.asterix.om.types.AUnionType;
 import org.apache.asterix.om.types.AbstractCollectionType;
 import org.apache.asterix.om.types.BuiltinType;
@@ -32,32 +30,48 @@
 
 public class ScalarVersionOfAggregateResultType extends AbstractResultTypeComputer {
 
-    public static final ScalarVersionOfAggregateResultType INSTANCE = new ScalarVersionOfAggregateResultType();
+    private final AggregateResultTypeComputer aggResultTypeComputer;
 
-    private ScalarVersionOfAggregateResultType() {
+    public ScalarVersionOfAggregateResultType(AggregateResultTypeComputer aggResultTypeComputer) {
+        this.aggResultTypeComputer = aggResultTypeComputer;
     }
 
     @Override
-    public void checkArgType(FunctionIdentifier funcId, int argIndex, IAType type, SourceLocation sourceLoc)
+    protected void checkArgType(FunctionIdentifier funcId, int argIndex, IAType argType, SourceLocation sourceLoc)
             throws AlgebricksException {
-        ATypeTag tag = type.getTypeTag();
-        if (tag != ATypeTag.ANY && tag != ATypeTag.ARRAY && tag != ATypeTag.MULTISET) {
-            throw new TypeMismatchException(sourceLoc, funcId, argIndex, tag, ATypeTag.ARRAY, ATypeTag.MULTISET);
+        if (argIndex == 0) {
+            switch (argType.getTypeTag()) {
+                case ARRAY:
+                case MULTISET:
+                    AbstractCollectionType act = (AbstractCollectionType) argType;
+                    aggResultTypeComputer.checkArgType(funcId, argIndex, act.getItemType(), sourceLoc);
+                    break;
+            }
         }
     }
 
     @Override
     protected IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes) throws AlgebricksException {
-        ATypeTag tag = strippedInputTypes[0].getTypeTag();
-        if (tag == ATypeTag.ANY) {
-            return BuiltinType.ANY;
+        IAType argType = strippedInputTypes[0];
+        switch (argType.getTypeTag()) {
+            case ARRAY:
+            case MULTISET:
+                AbstractCollectionType act = (AbstractCollectionType) argType;
+                IAType[] strippedInputTypes2 = strippedInputTypes.clone();
+                strippedInputTypes2[0] = act.getItemType();
+                IAType resultType = aggResultTypeComputer.getResultType(expr, strippedInputTypes2);
+                switch (resultType.getTypeTag()) {
+                    case NULL:
+                    case MISSING:
+                    case ANY:
+                        return resultType;
+                    case UNION:
+                        return AUnionType.createUnknownableType(((AUnionType) resultType).getActualType());
+                    default:
+                        return AUnionType.createUnknownableType(resultType);
+                }
+            default:
+                return BuiltinType.ANY;
         }
-        if (tag != ATypeTag.ARRAY && tag != ATypeTag.MULTISET) {
-            // this condition being true would've thrown an exception above, no?
-            return strippedInputTypes[0];
-        }
-        AbstractCollectionType act = (AbstractCollectionType) strippedInputTypes[0];
-        IAType t = act.getItemType();
-        return AUnionType.createUnknownableType(t);
     }
 }
diff --git a/asterixdb/asterix-runtime/src/test/java/org/apache/asterix/runtime/functions/ScalarAggregateTypeComputerTest.java b/asterixdb/asterix-runtime/src/test/java/org/apache/asterix/runtime/functions/ScalarAggregateTypeComputerTest.java
new file mode 100644
index 0000000..cbde36c
--- /dev/null
+++ b/asterixdb/asterix-runtime/src/test/java/org/apache/asterix/runtime/functions/ScalarAggregateTypeComputerTest.java
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.asterix.runtime.functions;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+import org.apache.asterix.dataflow.data.common.ExpressionTypeComputer;
+import org.apache.asterix.om.base.ABoolean;
+import org.apache.asterix.om.base.ADate;
+import org.apache.asterix.om.base.ADateTime;
+import org.apache.asterix.om.base.ADayTimeDuration;
+import org.apache.asterix.om.base.ADouble;
+import org.apache.asterix.om.base.ADuration;
+import org.apache.asterix.om.base.AFloat;
+import org.apache.asterix.om.base.AInt16;
+import org.apache.asterix.om.base.AInt32;
+import org.apache.asterix.om.base.AInt64;
+import org.apache.asterix.om.base.AInt8;
+import org.apache.asterix.om.base.AInterval;
+import org.apache.asterix.om.base.AOrderedList;
+import org.apache.asterix.om.base.ARecord;
+import org.apache.asterix.om.base.AString;
+import org.apache.asterix.om.base.ATime;
+import org.apache.asterix.om.base.AUnorderedList;
+import org.apache.asterix.om.base.AYearMonthDuration;
+import org.apache.asterix.om.base.IAObject;
+import org.apache.asterix.om.constants.AsterixConstantValue;
+import org.apache.asterix.om.exceptions.UnsupportedTypeException;
+import org.apache.asterix.om.functions.BuiltinFunctionInfo;
+import org.apache.asterix.om.functions.BuiltinFunctions;
+import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
+import org.apache.asterix.om.types.AOrderedListType;
+import org.apache.asterix.om.types.ARecordType;
+import org.apache.asterix.om.types.ATypeTag;
+import org.apache.asterix.om.types.AUnionType;
+import org.apache.asterix.om.types.AUnorderedListType;
+import org.apache.asterix.om.types.BuiltinType;
+import org.apache.asterix.om.types.IAType;
+import org.apache.commons.lang3.mutable.MutableObject;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import org.apache.hyracks.algebricks.core.algebra.expressions.AggregateFunctionCallExpression;
+import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
+import org.apache.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import org.apache.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
+import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+/**
+ * Test alignment of type computers between aggregate functions and their scalar versions
+ */
+@RunWith(Parameterized.class)
+public class ScalarAggregateTypeComputerTest {
+
+    private static final IAObject[] ITEMS = {
+            //
+            ABoolean.TRUE,
+            //
+            new AInt8((byte) 0),
+            //
+            new AInt16((short) 0),
+            //
+            new AInt32(0),
+            //
+            new AInt64(0),
+            //
+            new AFloat(0),
+            //
+            new ADouble(0),
+            //
+            new AString(""),
+            //
+            new ADate(0),
+            //
+            new ADateTime(0),
+            //
+            new ATime(0),
+            //
+            new ADuration(0, 0),
+            //
+            new AYearMonthDuration(0),
+            //
+            new ADayTimeDuration(0),
+            //
+            new AInterval(0, 0, ATypeTag.DATETIME.serialize()),
+            //
+            new AOrderedList(AOrderedListType.FULL_OPEN_ORDEREDLIST_TYPE, Collections.singletonList(new AString(""))),
+            //
+            new AUnorderedList(AUnorderedListType.FULLY_OPEN_UNORDEREDLIST_TYPE,
+                    Collections.singletonList(new AString(""))),
+            //
+            new ARecord(
+                    new ARecordType("record-type", new String[] { "a" }, new IAType[] { BuiltinType.ASTRING }, false),
+                    new IAObject[] { new AString("") }) };
+
+    // Test parameters
+    @Parameterized.Parameter
+    public String testName;
+
+    @Parameterized.Parameter(1)
+    public FunctionIdentifier scalarfid;
+
+    @Parameterized.Parameter(2)
+    public FunctionIdentifier aggfid;
+
+    @Parameterized.Parameter(3)
+    public IAObject item;
+
+    @Parameterized.Parameters(name = "ScalarAggregateTypeComputerTest {index}: {0}({3})")
+    public static Collection<Object[]> tests() {
+        List<Object[]> tests = new ArrayList<>();
+
+        FunctionCollection fcoll = FunctionCollection.createDefaultFunctionCollection();
+        for (IFunctionDescriptorFactory fdf : fcoll.getFunctionDescriptorFactories()) {
+            FunctionIdentifier fid = fdf.createFunctionDescriptor().getIdentifier();
+            FunctionIdentifier aggfid = BuiltinFunctions.getAggregateFunction(fid);
+            if (aggfid == null) {
+                continue;
+            }
+            for (IAObject item : ITEMS) {
+                tests.add(new Object[] { fid.getName(), fid, aggfid, item });
+            }
+
+        }
+        return tests;
+    }
+
+    @Test
+    public void test() throws Exception {
+
+        AOrderedListType listType = new AOrderedListType(item.getType(), null);
+        AOrderedList list = new AOrderedList(listType, Collections.singletonList(item));
+        ConstantExpression scalarArgExpr = new ConstantExpression(new AsterixConstantValue(list));
+        BuiltinFunctionInfo scalarfi = BuiltinFunctions.getBuiltinFunctionInfo(scalarfid);
+        ScalarFunctionCallExpression scalarCallExpr =
+                new ScalarFunctionCallExpression(scalarfi, new MutableObject<>(scalarArgExpr));
+        IAType scalarResultType = computeType(scalarCallExpr);
+
+        ConstantExpression aggArgExpr = new ConstantExpression(new AsterixConstantValue(item));
+        BuiltinFunctionInfo aggfi = BuiltinFunctions.getBuiltinFunctionInfo(aggfid);
+        AggregateFunctionCallExpression aggCallExpr = new AggregateFunctionCallExpression(aggfi, false,
+                Collections.singletonList(new MutableObject<>(aggArgExpr)));
+        IAType aggResultType = computeType(aggCallExpr);
+
+        if (!compareResultTypes(scalarResultType, aggResultType)) {
+            Assert.fail(String.format("%s(%s) returns %s != %s(%s) returns %s", scalarfid.getName(), item.getType(),
+                    formatResultType(scalarResultType), aggfid.getName(), item.getType(),
+                    formatResultType(aggResultType)));
+        }
+    }
+
+    private boolean compareResultTypes(IAType t1, IAType t2) {
+        // null means ERROR
+        if (t1 == null) {
+            // OK if both types are ERROR
+            return t2 == null;
+        } else if (t2 == null) {
+            return false;
+        }
+        boolean t1Union = false, t2Union = false;
+        if (t1.getTypeTag() == ATypeTag.UNION) {
+            t1Union = true;
+            t1 = ((AUnionType) t1).getActualType();
+        }
+        if (t2.getTypeTag() == ATypeTag.UNION) {
+            t2Union = true;
+            t2 = ((AUnionType) t2).getActualType();
+        }
+        return (t1Union == t2Union) && t1.deepEqual(t2);
+    }
+
+    private String formatResultType(IAType t) {
+        return t == null ? "ERROR" : t.toString();
+    }
+
+    private IAType computeType(AbstractFunctionCallExpression callExpr) throws AlgebricksException {
+        try {
+            BuiltinFunctionInfo fi = Objects.requireNonNull((BuiltinFunctionInfo) callExpr.getFunctionInfo());
+            return fi.getResultTypeComputer().computeType(callExpr, EMPTY_TYPE_ENV, null);
+        } catch (UnsupportedTypeException e) {
+            return null;
+        }
+    }
+
+    private static final IVariableTypeEnvironment EMPTY_TYPE_ENV = new IVariableTypeEnvironment() {
+
+        @Override
+        public boolean substituteProducedVariable(LogicalVariable v1, LogicalVariable v2) {
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public void setVarType(LogicalVariable var, Object type) {
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariables,
+                List<List<LogicalVariable>> correlatedNullableVariableLists) {
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public Object getVarType(LogicalVariable var) {
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public Object getType(ILogicalExpression expr) throws AlgebricksException {
+            return ExpressionTypeComputer.INSTANCE.getType(expr, null, this);
+        }
+    };
+}