diff --git a/pom.xml b/pom.xml
index 890b0ec..4dd02f6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -37,7 +37,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <junit.version>4.12</junit.version>
         <tinkerpop.version>3.1.0-incubating</tinkerpop.version>
-        <calcite.version>1.5.0</calcite.version>
+        <calcite.version>1.6.0</calcite.version>
     </properties>
 
     <dependencies>
diff --git a/src/main/java/org/twilmes/sql/gremlin/processor/FieldMapVisitor.java b/src/main/java/org/twilmes/sql/gremlin/processor/FieldMapVisitor.java
index 9d8425b..0b13044 100644
--- a/src/main/java/org/twilmes/sql/gremlin/processor/FieldMapVisitor.java
+++ b/src/main/java/org/twilmes/sql/gremlin/processor/FieldMapVisitor.java
@@ -19,6 +19,7 @@
 
 package org.twilmes.sql.gremlin.processor;
 
+import org.apache.calcite.adapter.enumerable.EnumerableCalc;
 import org.twilmes.sql.gremlin.rel.GremlinToEnumerableConverter;
 import org.apache.calcite.adapter.enumerable.EnumerableJoin;
 import org.apache.calcite.rel.RelNode;
@@ -95,6 +96,20 @@ private GremlinToEnumerableConverter getConverter(int fieldIndex, String field,
             List<String> fieldNames = join.getRowType().getFieldNames();
             final String chosenField = fieldNames.get(fieldIndex);
             return fieldMap.get(join).get(chosenField);
+        } else if (node instanceof EnumerableCalc) {
+            final EnumerableCalc calc = (EnumerableCalc) node;
+            for (RelNode relNode : calc.getInputs()) {
+                if (relNode instanceof EnumerableJoin) {
+                    return getConverter(fieldIndex, field, relNode);
+                } else {
+                    try {
+                        GremlinToEnumerableConverter converter = (GremlinToEnumerableConverter) relNode;
+                        return converter;
+                    } catch (ClassCastException e) {
+
+                    }
+                }
+            }
         }
         return null;
     }
diff --git a/src/main/java/org/twilmes/sql/gremlin/processor/GremlinCompiler.java b/src/main/java/org/twilmes/sql/gremlin/processor/GremlinCompiler.java
index 4bc1f4b..11ac45b 100644
--- a/src/main/java/org/twilmes/sql/gremlin/processor/GremlinCompiler.java
+++ b/src/main/java/org/twilmes/sql/gremlin/processor/GremlinCompiler.java
@@ -121,7 +121,7 @@ public List<Object> execute(String sql) {
             final FieldMapVisitor fieldMapper = new FieldMapVisitor();
             new RelWalker(root, fieldMapper);
             final TraversalVisitor traversalVisitor = new TraversalVisitor(graph.traversal(),
-                    scanMap, fieldMapper.getFieldMap());
+                    scanMap, fieldMapper.getFieldMap(), schemaConfig);
             new RelWalker(root, traversalVisitor);
 
             traversal = TraversalBuilder.buildMatch(graph.traversal(), traversalVisitor.getTableTraversalMap(),
diff --git a/src/main/java/org/twilmes/sql/gremlin/processor/JoinQueryExecutor.java b/src/main/java/org/twilmes/sql/gremlin/processor/JoinQueryExecutor.java
index 817a263..8e5040e 100644
--- a/src/main/java/org/twilmes/sql/gremlin/processor/JoinQueryExecutor.java
+++ b/src/main/java/org/twilmes/sql/gremlin/processor/JoinQueryExecutor.java
@@ -22,6 +22,7 @@
 import org.twilmes.sql.gremlin.rel.GremlinToEnumerableConverter;
 import org.twilmes.sql.gremlin.rel.GremlinTraversalScan;
 import org.twilmes.sql.gremlin.rel.GremlinTraversalToEnumerableRelConverter;
+import org.twilmes.sql.gremlin.schema.TableColumn;
 import org.twilmes.sql.gremlin.schema.TableDef;
 import org.twilmes.sql.gremlin.schema.TableUtil;
 import org.apache.calcite.adapter.enumerable.EnumerableInterpretable;
@@ -153,8 +154,8 @@ public List<Object> run() {
     }
 
     private List<Object> project(Map<String, String> fieldToTableMap, List<String> fields,
-                                   List<Map<String, ? extends Element>> results,
-                                   Map<String, TableDef> tableIdToTableDefMap) {
+                                 List<Map<String, ? extends Element>> results,
+                                 Map<String, TableDef> tableIdToTableDefMap) {
         final List<Object> rows = new ArrayList<>(results.size());
         Map<String, String> labelTableIdMap = new HashMap<>();
         for (Map.Entry<String, TableDef> entry : tableIdToTableDefMap.entrySet()) {
@@ -185,8 +186,8 @@ private List<Object> project(Map<String, String> fieldToTableMap, List<String> f
                         }
                     }
                 }
-                final Property<Object> property = result.get(tableId).
-                        property(tableIdToTableDefMap.get(tableId).getColumn(simpleFieldName.toLowerCase()).getPropertyName());
+                TableColumn tableColumn = tableIdToTableDefMap.get(tableId).getColumn(simpleFieldName.toLowerCase());
+                final Property<Object> property = tableColumn == null ? Property.empty() : result.get(tableId).property(tableColumn.getPropertyName());
                 if(!(property instanceof EmptyProperty || property instanceof EmptyVertexProperty)) {
                     if(result.get(tableId).label().equals(tableIdToTableDefMap.get(tableId).label)) {
                         val = property.value();
diff --git a/src/main/java/org/twilmes/sql/gremlin/processor/TraversalVisitor.java b/src/main/java/org/twilmes/sql/gremlin/processor/TraversalVisitor.java
index 4cf8592..9529b47 100644
--- a/src/main/java/org/twilmes/sql/gremlin/processor/TraversalVisitor.java
+++ b/src/main/java/org/twilmes/sql/gremlin/processor/TraversalVisitor.java
@@ -25,6 +25,7 @@
 import org.apache.calcite.rel.RelNode;
 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource;
+import org.twilmes.sql.gremlin.schema.SchemaConfig;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -38,6 +39,7 @@ public class TraversalVisitor implements RelVisitor {
 
     private final Map<GremlinToEnumerableConverter, List<RelNode>> scanMap;
     private final Map<EnumerableJoin, Map<String, GremlinToEnumerableConverter>> fieldMap;
+    private final SchemaConfig schemaConfig;  // may use to check if join is valid
     private Integer id = 0;
     private Map<GremlinToEnumerableConverter, String> tableIdMap = new HashMap<>();
     private Map<String, GremlinToEnumerableConverter> tableIdConverterMap = new HashMap<>();
@@ -50,9 +52,11 @@ public class TraversalVisitor implements RelVisitor {
 
     public TraversalVisitor(GraphTraversalSource traversalSource,
                             Map<GremlinToEnumerableConverter, List<RelNode>> scanMap,
-                            Map<EnumerableJoin, Map<String, GremlinToEnumerableConverter>> fieldMap) {
+                            Map<EnumerableJoin, Map<String, GremlinToEnumerableConverter>> fieldMap,
+                            SchemaConfig schemaConfig) {
         this.scanMap = scanMap;
         this.fieldMap = fieldMap;
+        this.schemaConfig = schemaConfig;
     }
 
     public List<Pair<String, String>> getJoinPairs() { return joinPairs; }
@@ -71,6 +75,9 @@ public void visit(RelNode node) {
         RelNode left = join.getLeft();
         RelNode right = join.getRight();
 
+        // TODO: should we check schema to see if the join is valid?
+        // found some cases the join happens to two tables that has no relationship
+
         final Integer leftKeyId = join.getLeftKeys().get(0);
         final Integer rightKeyId = join.getRightKeys().get(0);
 
@@ -82,7 +89,25 @@ public void visit(RelNode node) {
         final String rightAliasedColumn = rightJoinFields.get(rightKeyId);
 
         if(!(left instanceof GremlinToEnumerableConverter)) {
-            left = fieldMap.get(left).get(leftAliasedColumn);
+            if (fieldMap.get(left) != null && fieldMap.get(left).containsKey(leftAliasedColumn)) {
+                left = fieldMap.get(left).get(leftAliasedColumn);
+            } else {
+                Map<String, GremlinToEnumerableConverter> leftMap = fieldMap.get(left);
+                if (leftMap == null) {
+                    for(EnumerableJoin ej : fieldMap.keySet()) {
+                        if (ej.getLeft().equals(left)) {
+                            left = fieldMap.get(ej).get(leftAliasedColumn);
+                            List<RelNode> scan = scanMap.get(left);
+                            GraphTraversal leftTraversal = TraversalBuilder.toTraversal(scan);
+                            traversals.add(leftTraversal);
+                            tableTraversalMap.put(getTableId((GremlinToEnumerableConverter) left), leftTraversal);
+                            break;
+                        }
+                    }
+                } else {
+                    left = leftMap.get(leftAliasedColumn);
+                }
+            }
         } else {
             List<RelNode> scan = scanMap.get(left);
             GraphTraversal leftTraversal = TraversalBuilder.toTraversal(scan);
@@ -90,7 +115,13 @@ public void visit(RelNode node) {
             tableTraversalMap.put(getTableId((GremlinToEnumerableConverter) left), leftTraversal);
         }
         if(!(right instanceof GremlinToEnumerableConverter)) {
-            right = fieldMap.get(join).get(rightAliasedColumn);
+            if (fieldMap.get(join) != null && fieldMap.get(join).containsKey(rightAliasedColumn)) {
+                right = fieldMap.get(join).get(rightAliasedColumn);
+                List<RelNode> scan = scanMap.get(right);
+                GraphTraversal rightTraversal = TraversalBuilder.toTraversal(scan);
+                traversals.add(rightTraversal);
+                tableTraversalMap.put(getTableId((GremlinToEnumerableConverter) right), rightTraversal);
+            }
         } else {
             List<RelNode> scan = scanMap.get(right);
             GraphTraversal rightTraversal = TraversalBuilder.toTraversal(scan);
diff --git a/src/main/java/org/twilmes/sql/gremlin/rel/GremlinToEnumerableConverter.java b/src/main/java/org/twilmes/sql/gremlin/rel/GremlinToEnumerableConverter.java
index 7d2c4bc..81383af 100644
--- a/src/main/java/org/twilmes/sql/gremlin/rel/GremlinToEnumerableConverter.java
+++ b/src/main/java/org/twilmes/sql/gremlin/rel/GremlinToEnumerableConverter.java
@@ -27,6 +27,7 @@
 import org.apache.calcite.plan.*;
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.convert.ConverterImpl;
+import org.apache.calcite.rel.metadata.RelMetadataQuery;
 
 import java.util.List;
 
@@ -50,8 +51,8 @@ public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
     }
 
     @Override
-    public RelOptCost computeSelfCost(RelOptPlanner planner) {
-        return super.computeSelfCost(planner).multiplyBy(.1);
+    public RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
+        return super.computeSelfCost(planner, mq).multiplyBy(.1);
     }
 
     @Override
diff --git a/src/main/java/org/twilmes/sql/gremlin/schema/TableUtil.java b/src/main/java/org/twilmes/sql/gremlin/schema/TableUtil.java
index a8742fc..d637da9 100644
--- a/src/main/java/org/twilmes/sql/gremlin/schema/TableUtil.java
+++ b/src/main/java/org/twilmes/sql/gremlin/schema/TableUtil.java
@@ -61,11 +61,23 @@ public static Object convertType(Object value, TableColumn column) {
             case "string":
                 return value;
             case "integer":
-                return ((Number) value).intValue();
+                try {
+                    return Integer.valueOf(String.valueOf(value));
+                } catch ( NumberFormatException e ) {
+                    return value;
+                }
             case "long":
-                return ((Number) value).longValue();
+                try {
+                    return Long.valueOf(String.valueOf(value));
+                } catch ( NumberFormatException e ) {
+                    return value;
+                }
             case "double":
-                return ((Number) value).doubleValue();
+                try {
+                    return Double.valueOf(String.valueOf(value));
+                } catch ( NumberFormatException e ) {
+                    return value;
+                }
             case "boolean":
                 if(value instanceof Number) {
                     if(value.equals(0)) {