diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/CallExpr.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/CallExpr.java
index c7d48b6..44a40c4 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/CallExpr.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/CallExpr.java
@@ -65,4 +65,9 @@
     public <R, T> R accept(ILangVisitor<R, T> visitor, T arg) throws AsterixException {
         return visitor.visit(this, arg);
     }
+
+    @Override
+    public String toString() {
+        return "call " + String.valueOf(functionSignature);
+    }
 }
diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/FieldAccessor.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/FieldAccessor.java
index 2517add..e23c799 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/FieldAccessor.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/FieldAccessor.java
@@ -49,4 +49,8 @@
         return visitor.visit(this, arg);
     }
 
+    @Override
+    public String toString() {
+        return String.valueOf(expr) + "." + ident.toString();
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromClause.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromClause.java
index 802869d..da6c512 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromClause.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromClause.java
@@ -21,6 +21,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.apache.asterix.common.exceptions.AsterixException;
 import org.apache.asterix.lang.common.base.Clause;
@@ -48,4 +49,9 @@
     public List<FromTerm> getFromTerms() {
         return fromTerms;
     }
+
+    @Override
+    public String toString() {
+        return fromTerms.stream().map(String::valueOf).collect(Collectors.joining(", "));
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromTerm.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromTerm.java
index 5e8cd9c..8a756c7 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromTerm.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/FromTerm.java
@@ -82,4 +82,8 @@
         return posVar != null;
     }
 
+    @Override
+    public String toString() {
+        return String.valueOf(leftExpr) + " AS " + String.valueOf(leftVar);
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/Projection.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/Projection.java
index 6ca9b71..f73ec1e 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/Projection.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/Projection.java
@@ -76,4 +76,9 @@
     public boolean exprStar() {
         return exprStar;
     }
+
+    @Override
+    public String toString() {
+        return star ? "*" : (String.valueOf(expr) + (exprStar ? ".*" : (hasName() ? " as " + getName() : "")));
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectClause.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectClause.java
index c6b4e24..42c8b29 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectClause.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectClause.java
@@ -66,4 +66,9 @@
         return distinct;
     }
 
+    @Override
+    public String toString() {
+        return "select " + (distinct ? "distinct " : "")
+                + (selectElement() ? "element " + String.valueOf(selectElement) : String.valueOf(selectRegular));
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectElement.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectElement.java
index e13506a..14efd0f 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectElement.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectElement.java
@@ -50,4 +50,9 @@
     public void setExpression(Expression expr) {
         this.expr = expr;
     }
+
+    @Override
+    public String toString() {
+        return String.valueOf(expr);
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectRegular.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectRegular.java
index e8a14ea..4703e01 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectRegular.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/clause/SelectRegular.java
@@ -20,6 +20,7 @@
 package org.apache.asterix.lang.sqlpp.clause;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.apache.asterix.common.exceptions.AsterixException;
 import org.apache.asterix.lang.common.base.Clause;
@@ -47,4 +48,9 @@
     public List<Projection> getProjections() {
         return projections;
     }
+
+    @Override
+    public String toString() {
+        return projections.stream().map(String::valueOf).collect(Collectors.joining(", "));
+    }
 }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
index be9c697..6db1ea3 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppGroupBySugarVisitor.java
@@ -135,8 +135,7 @@
         // Construct the select expression.
         SelectBlock selectBlock = new SelectBlock(selectClause, fromClause, null, null, null, null, null);
         SelectSetOperation selectSetOperation = new SelectSetOperation(new SetOperationInput(selectBlock, null), null);
-        SelectExpression selectExpression = new SelectExpression(null, selectSetOperation, null, null, false);
-        selectExpression.setSubquery(true);
+        SelectExpression selectExpression = new SelectExpression(null, selectSetOperation, null, null, true);
 
         // replace variable expressions with field access
         Map<VariableExpr, Expression> varExprMap = new HashMap<>();