diff --git a/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/SetAsterixPhysicalOperatorsRule.java b/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/SetAsterixPhysicalOperatorsRule.java
index bfd1a70..1ba5702 100644
--- a/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/SetAsterixPhysicalOperatorsRule.java
+++ b/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/SetAsterixPhysicalOperatorsRule.java
@@ -21,9 +21,6 @@
 import java.util.ArrayList;
 import java.util.List;
 
-import org.apache.commons.lang3.mutable.Mutable;
-import org.apache.commons.lang3.mutable.MutableObject;
-
 import org.apache.asterix.algebra.operators.physical.BTreeSearchPOperator;
 import org.apache.asterix.algebra.operators.physical.InvertedIndexPOperator;
 import org.apache.asterix.algebra.operators.physical.RTreeSearchPOperator;
@@ -33,6 +30,8 @@
 import org.apache.asterix.om.functions.AsterixBuiltinFunctions;
 import org.apache.asterix.optimizer.rules.am.AccessMethodJobGenParams;
 import org.apache.asterix.optimizer.rules.am.BTreeJobGenParams;
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
 import org.apache.hyracks.algebricks.common.exceptions.NotImplementedException;
 import org.apache.hyracks.algebricks.common.utils.Pair;
@@ -148,7 +147,9 @@
                                     ExternalGroupByPOperator externalGby = new ExternalGroupByPOperator(
                                             gby.getGroupByList(),
                                             physicalOptimizationConfig.getMaxFramesExternalGroupBy(),
-                                            physicalOptimizationConfig.getExternalGroupByTableSize());
+                                            physicalOptimizationConfig.getExternalGroupByTableSize(),
+                                            (long) physicalOptimizationConfig.getMaxFramesExternalGroupBy()
+                                                    * physicalOptimizationConfig.getFrameSize());
                                     generateMergeAggregationExpressions(gby, context);
                                     op.setPhysicalOperator(externalGby);
                                     setToExternalGby = true;
diff --git a/asterix-om/src/main/java/org/apache/asterix/om/base/ARecord.java b/asterix-om/src/main/java/org/apache/asterix/om/base/ARecord.java
index 438617f..79dd63c 100644
--- a/asterix-om/src/main/java/org/apache/asterix/om/base/ARecord.java
+++ b/asterix-om/src/main/java/org/apache/asterix/om/base/ARecord.java
@@ -88,13 +88,15 @@
     public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("ARecord: { ");
-        for (int i = 0; i < fields.length; i++) {
-            if (i > 0) {
-                sb.append(", ");
+        if (fields != null) {
+            for (int i = 0; i < fields.length; i++) {
+                if (i > 0) {
+                    sb.append(", ");
+                }
+                sb.append(type.getFieldNames()[i]);
+                sb.append(": ");
+                sb.append(fields[i]);
             }
-            sb.append(type.getFieldNames()[i]);
-            sb.append(": ");
-            sb.append(fields[i]);
         }
         sb.append(" }");
         return sb.toString();