DRILL-1062: Implemented null ordering (NULLS FIRST/NULLS LAST).

Primary:
- Split "compare_to" function templates (for sorting) into
  "compare_to_nulls_high" and "compare_to_nulls_low" versions.
- Added tests to verify ORDER BY ordering.
- Added tests to verify merge join order correctness.
- Implemented java.sql.DatabaseMetaData.nullsAreSortedHigh(), etc.
Secondary:
- Eliminated DateInterfaceFunctions.java template (merged into other).
- Renamed comparison-related template data objects and file names.
- Eliminated unused template macros, function template classes.
- Overhauled Order.Ordering; added unit test.
- Regularized some generated-class names.
Miscellaneous:
- Added toString() to ExpressionPosition, Order.Ordering, JoinStatus.
- Fixed some typos.
- Fixed some comment syntax.

22 files changed, 182 insertions, 905 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/client/PrintingResultsListener.java b/exec/java-exec/src/main/java/org/apache/drill/exec/client/PrintingResultsListener.java
index 1ed3cb349..926e703c5 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/client/PrintingResultsListener.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/client/PrintingResultsListener.java
@@ -53,6 +53,7 @@ public class PrintingResultsListener implements UserResultsListener {
   @Override
   public void submissionFailed(RpcException ex) {
     exception = ex;
+    System.out.println("Exception (no rows returned): " + ex );
     latch.countDown();
   }
 
@@ -87,7 +88,7 @@ public class PrintingResultsListener implements UserResultsListener {
     if (isLastChunk) {
       allocator.close();
       latch.countDown();
-      System.out.println("Total rows returned : " + count.get());
+      System.out.println("Total rows returned: " + count.get());
     }
 
   }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java
index e1ad85492..3565bf470 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java
@@ -203,7 +203,7 @@ public class ExpressionTreeMaterializer {
       List<LogicalExpression> args = Lists.newArrayList();
       for (int i = 0; i < call.args.size(); ++i) {
         LogicalExpression newExpr = call.args.get(i).accept(this, registry);
-        assert newExpr != null : String.format("Materialization of %s return a null expression.", call.args.get(i));
+        assert newExpr != null : String.format("Materialization of %s returned a null expression.", call.args.get(i));
         args.add(newExpr);
       }
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java
index 1f732a398..15c7e196d 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java
@@ -28,15 +28,27 @@ import java.lang.annotation.Target;
 public @interface FunctionTemplate {
 
   /**
-   * Use this annotation if there is only one name for function
-   * Note: If you use this annotation don't use {@link #names()}
+   * Name of function (when only one.)
+   * Use this annotation element if there is only one name for the function.
+   * Note: If you use this annotation don't use {@link #names()}.
+   * <p>
+   *   TODO:  Refer to wherever list of possible or at least known names is,
+   *   to resolve the current issue of spaces vs. underlines in names (e.g., we
+   *   have both "less_than" and "less than".
+   * </p>
    * @return
    */
   String name() default "";
 
   /**
-   * Use this annotation if there are multiple names for function
-   * Note: If you use this annotation don't use {@link #name()}
+   * Names of function (when multiple).
+   * Use this annotation element if there are multiple names for the function.
+   * Note: If you use this annotation don't use {@link #name()}.
+   * <p>
+   *   TODO:  Refer to wherever list of possible or at least known names is,
+   *   to resolve the current issue of spaces vs. underlines in names (e.g., we
+   *   have both "less_than" and "less than".
+   * </p>
    * @return
    */
   String[] names() default {};
@@ -49,10 +61,21 @@ public @interface FunctionTemplate {
   FunctionCostCategory costCategory() default FunctionCostCategory.SIMPLE;
 
   public static enum NullHandling {
-    INTERNAL, NULL_IF_NULL;
+    /**
+     * Method handles nulls.
+     */
+    INTERNAL,
+
+    /**
+     * Null output if any null input:
+     * Indicates that a method's associated logical operation returns NULL if
+     * either input is NULL, and therefore that the method must not be called
+     * with null inputs.  (The calling framework must handle NULLs.)
+     */
+    NULL_IF_NULL;
   }
 
-  public static enum FunctionScope{
+  public static enum FunctionScope {
     SIMPLE,
     POINT_AGGREGATE,
     DECIMAL_AGGREGATE,
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionGenerationHelper.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionGenerationHelper.java
index d007d7c54..19cd1d851 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionGenerationHelper.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionGenerationHelper.java
@@ -29,28 +29,58 @@ import org.apache.drill.common.types.TypeProtos.MinorType;
 import org.apache.drill.common.types.Types;
 import org.apache.drill.exec.expr.ClassGenerator.HoldingContainer;
 import org.apache.drill.exec.expr.HoldingContainerExpression;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 public class FunctionGenerationHelper {
-  public static final String COMPARE_TO = "compare_to";
+  public static final String COMPARE_TO_NULLS_HIGH = "compare_to_nulls_high";
+  public static final String COMPARE_TO_NULLS_LOW = "compare_to_nulls_low";
 
   /**
-   * Given materialized arguments find the "compare_to" FunctionHolderExpression
-   * @param left
-   * @param right
-   * @param registry
-   * @return FunctionHolderExpression containing the function implementation
+   * Finds ordering comparator ("compare_to...") FunctionHolderExpression with
+   * a specified ordering for NULL (and considering NULLS <i>equal</i>).
+   * @param  null_high  whether NULL should compare as the lowest value (if
+   *                    {@code false}) or the highest value (if {@code true})
+   * @param  left  ...
+   * @param  right  ...
+   * @param  registry  ...
+   * @return
+   *     FunctionHolderExpression containing the found function implementation
    */
-  public static FunctionHolderExpression getComparator(HoldingContainer left,
-    HoldingContainer right,
-    FunctionImplementationRegistry registry) {
-    if (! isComparableType(left.getMajorType()) || ! isComparableType(right.getMajorType()) ){
-      throw new UnsupportedOperationException(formatCanNotCompareMsg(left.getMajorType(), right.getMajorType()));
+  public static FunctionHolderExpression getOrderingComparator(
+      boolean null_high,
+      HoldingContainer left,
+      HoldingContainer right,
+      FunctionImplementationRegistry registry) {
+    final String comparator_name =
+        null_high ? COMPARE_TO_NULLS_HIGH : COMPARE_TO_NULLS_LOW;
+
+    if (   ! isComparableType(left.getMajorType() )
+        || ! isComparableType(right.getMajorType() ) ) {
+      throw new UnsupportedOperationException(
+          formatCanNotCompareMsg(left.getMajorType(), right.getMajorType()));
     }
+    return getFunctionExpression(comparator_name, Types.required(MinorType.INT),
+                                 registry, left, right);
+  }
 
-    return getFunctionExpression(COMPARE_TO, Types.required(MinorType.INT), registry, left, right);
+  /**
+   * Finds ordering comparator ("compare_to...") FunctionHolderExpression with
+   * a "NULL high" ordering (and considering NULLS <i>equal</i>).
+   * @param  left  ...
+   * @param  right  ...
+   * @param  registry  ...
+   * @return FunctionHolderExpression containing the function implementation
+   * @see #getComparator
+   */
+  public static FunctionHolderExpression getOrderingComparatorNullsHigh(
+      HoldingContainer left,
+      HoldingContainer right,
+      FunctionImplementationRegistry registry) {
+    return getOrderingComparator(true, left, right, registry);
   }
 
-  public static FunctionHolderExpression getFunctionExpression(String name, MajorType returnType, FunctionImplementationRegistry registry, HoldingContainer... args) {
+  public static FunctionHolderExpression getFunctionExpression(
+      String name, MajorType returnType, FunctionImplementationRegistry registry, HoldingContainer... args) {
     List<MajorType> argTypes = new ArrayList<MajorType>(args.length);
     List<LogicalExpression> argExpressions = new ArrayList<LogicalExpression>(args.length);
     for(HoldingContainer c : args) {
@@ -69,10 +99,10 @@ public class FunctionGenerationHelper {
     sb.append("( ");
     for(int i =0; i < args.length; i++) {
       MajorType mt = args[i].getMajorType();
-      appendType(mt, sb);
       if (i != 0) {
         sb.append(", ");
       }
+      appendType(mt, sb);
     }
     sb.append(" ) returns ");
     appendType(returnType, sb);
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionImplementationRegistry.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionImplementationRegistry.java
index 25dcbbcbe..55e4121d3 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionImplementationRegistry.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionImplementationRegistry.java
@@ -99,11 +99,15 @@ public class FunctionImplementationRegistry {
     return functionResolver.getBestMatch(drillFuncRegistry.getMethods(functionReplacement(functionCall)), functionCall);
   }
 
-  // Check if this Function Replacement is Needed; if yes, return a new name. otherwise, return the original name
+  // Check if this Function Replacement is needed; if yes, return a new name. otherwise, return the original name
   private String functionReplacement(FunctionCall functionCall) {
     String funcName = functionCall.getName();
-    if(optionManager != null && optionManager.getOption(ExecConstants.CAST_TO_NULLABLE_NUMERIC).bool_val && CastFunctions.isReplacementNeeded(functionCall.args.get(0).getMajorType().getMinorType(), funcName)) {
-      org.apache.drill.common.types.TypeProtos.DataMode dataMode = functionCall.args.get(0).getMajorType().getMode();
+    if (optionManager != null
+        && optionManager.getOption(ExecConstants.CAST_TO_NULLABLE_NUMERIC).bool_val
+        && CastFunctions.isReplacementNeeded(functionCall.args.get(0).getMajorType().getMinorType(),
+                                             funcName)) {
+      org.apache.drill.common.types.TypeProtos.DataMode dataMode =
+          functionCall.args.get(0).getMajorType().getMode();
       funcName = CastFunctions.getReplacingCastFunction(funcName, dataMode);
     }
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/BitFunctions.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/BitFunctions.java
index 3fe489fd9..ae428726a 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/BitFunctions.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/BitFunctions.java
@@ -27,9 +27,17 @@ import org.apache.drill.exec.expr.holders.BitHolder;
 import org.apache.drill.exec.expr.holders.IntHolder;
 import org.apache.drill.exec.record.RecordBatch;
 
+/**
+ * Function templates for Bit/BOOLEAN functions other than comparison
+ * functions.  (Bit/BOOLEAN comparison functions are generated in
+ * ComparisonFunctions.java template.)
+ *
+ */
 public class BitFunctions {
 
-  @FunctionTemplate(names = {"booleanOr", "or", "||"}, scope = FunctionScope.SC_BOOLEAN_OPERATOR, nulls = NullHandling.NULL_IF_NULL)
+  @FunctionTemplate(names = {"booleanOr", "or", "||"},
+                    scope = FunctionScope.SC_BOOLEAN_OPERATOR,
+                    nulls = NullHandling.NULL_IF_NULL)
   public static class BitOr implements DrillSimpleFunc {
 
     @Param BitHolder left;
@@ -43,7 +51,9 @@ public class BitFunctions {
     }
   }
 
-  @FunctionTemplate(names = {"booleanAnd", "and", "&&"}, scope = FunctionScope.SC_BOOLEAN_OPERATOR, nulls = NullHandling.NULL_IF_NULL)
+  @FunctionTemplate(names = {"booleanAnd", "and", "&&"},
+                    scope = FunctionScope.SC_BOOLEAN_OPERATOR,
+                    nulls = NullHandling.NULL_IF_NULL)
   public static class BitAnd implements DrillSimpleFunc {
 
     @Param BitHolder left;
@@ -58,7 +68,9 @@ public class BitFunctions {
   }
 
 
-  @FunctionTemplate(names = {"xor", "^"}, scope = FunctionScope.SIMPLE, nulls = NullHandling.NULL_IF_NULL)
+  @FunctionTemplate(names = {"xor", "^"},
+                    scope = FunctionScope.SIMPLE,
+                    nulls = NullHandling.NULL_IF_NULL)
   public static class IntXor implements DrillSimpleFunc {
 
     @Param IntHolder left;
@@ -72,32 +84,4 @@ public class BitFunctions {
     }
   }
 
-  @FunctionTemplate(names = {"equal","==","="}, scope = FunctionTemplate.FunctionScope.SIMPLE, nulls = NullHandling.NULL_IF_NULL)
-  public static class EqualsBitBit implements DrillSimpleFunc {
-
-    @Param BitHolder left;
-    @Param BitHolder right;
-    @Output BitHolder out;
-
-    public void setup(RecordBatch b) {}
-
-    public void eval() {
-      out.value = left.value == right.value ? 1 : 0;
-
-    }
-  }
-
-  @FunctionTemplate(name = "compare_to", scope = FunctionTemplate.FunctionScope.SIMPLE, nulls = NullHandling.NULL_IF_NULL)
-  public static class CompareBitBit implements DrillSimpleFunc {
-
-    @Param BitHolder left;
-    @Param BitHolder right;
-    @Output IntHolder out;
-
-    public void setup(RecordBatch b) {}
-
-    public void eval() {
-      out.value = left.value < right.value ? -1 : ((left.value == right.value)? 0 : 1);
-    }
-  }
 }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctions.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctions.java
deleted file mode 100644
index bf42ce6c0..000000000
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctions.java
+++ /dev/null
@@ -1,572 +0,0 @@
-/**
- * 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.drill.exec.expr.fn.impl;
-
-
-public class ComparisonFunctions {
-    static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(MathFunctions.class);
-
-//    private ComparisonFunctions() {}
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntEqual implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value == right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntEqual implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value == right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4Equal implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value == right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8Equal implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value == right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "not equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntNotEqual implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value != right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "not equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntNotEqual implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value != right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "not equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4NotEqual implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value != right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "not equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8NotEqual implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value != right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntGreaterThan implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value > right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntGreaterThan implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value > right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4GreaterThan implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value > right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8GreaterThan implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value > right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntGreaterThanEqual implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value >= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntGreaterThanEqual implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value >= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4GreaterThanEqual implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value >= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8GreaterThanEqual implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value >= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntLessThan implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value < right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntLessThan implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value < right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4LessThan implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value < right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8LessThan implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value < right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class IntLessThanEqual implements DrillSimpleFunc {
-//
-//        @Param IntHolder left;
-//        @Param IntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value <= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class BigIntLessThanEqual implements DrillSimpleFunc {
-//
-//        @Param BigIntHolder left;
-//        @Param BigIntHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value <= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float4LessThanEqual implements DrillSimpleFunc {
-//
-//        @Param Float4Holder left;
-//        @Param Float4Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value <= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class Float8LessThanEqual implements DrillSimpleFunc {
-//
-//        @Param Float8Holder left;
-//        @Param Float8Holder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = (left.value <= right.value) ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryEqual implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarBinaryHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 0 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarCharEqual implements DrillSimpleFunc {
-//
-//        @Param VarCharHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 0 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "equal", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryCharEqual implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 0 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryGTE implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarBinaryHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) > -1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarCharGTE implements DrillSimpleFunc {
-//
-//        @Param VarCharHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) > -1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryCharGTE implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) > -1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryGT implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarBinaryHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarCharGT implements DrillSimpleFunc {
-//
-//        @Param VarCharHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "greater than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryCharGT implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == 1? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryLTE implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarBinaryHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) < 1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarCharLTE implements DrillSimpleFunc {
-//
-//        @Param VarCharHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) < 1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than or equal to", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryCharLTE implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) < 1? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryLT implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarBinaryHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == -1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarCharLT implements DrillSimpleFunc {
-//
-//        @Param VarCharHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == -1 ? 1 : 0;
-//        }
-//    }
-//
-//    @FunctionTemplate(name = "less than", scope = FunctionTemplate.FunctionScope.SIMPLE)
-//    public static class VarBinaryCharLT implements DrillSimpleFunc {
-//
-//        @Param VarBinaryHolder left;
-//        @Param VarCharHolder right;
-//        @Output BitHolder out;
-//
-//        public void setup(RecordBatch b) {}
-//
-//        public void eval() {
-//            out.value = org.apache.drill.exec.expr.fn.impl.VarHelpers.compare(left, right) == -1 ? 1 : 0;
-//        }
-//    }
-
-}
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctionsNullable.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctionsNullable.java
deleted file mode 100644
index 570aaeb05..000000000
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ComparisonFunctionsNullable.java
+++ /dev/null
@@ -1,250 +0,0 @@
-/**
- * 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.drill.exec.expr.fn.impl;
-
-import org.apache.drill.exec.expr.DrillSimpleFunc;
-import org.apache.drill.exec.expr.annotations.FunctionTemplate;
-import org.apache.drill.exec.expr.annotations.Output;
-import org.apache.drill.exec.expr.annotations.Param;
-import org.apache.drill.exec.expr.holders.BitHolder;
-import org.apache.drill.exec.expr.holders.NullableBigIntHolder;
-import org.apache.drill.exec.expr.holders.NullableIntHolder;
-import org.apache.drill.exec.record.RecordBatch;
-
-public class ComparisonFunctionsNullable {
-    static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ComparisonFunctionsNullable.class);
-
-    private ComparisonFunctionsNullable() {}
-
-    @FunctionTemplate(names = {"equal", "=", "=="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntEqual implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value == right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"equal", "=", "=="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntEqual implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value == right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"not equal", "<>", "!="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntNotEqual implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value != right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"not equal", "<>", "!="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntNotEqual implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value != right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"less than","<"}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntLessThan implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value < right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"less than","<"}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntLessThan implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value < right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"less than or equal to","<="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntLessThanEqual implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value <= right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"less than or equal to","<="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntLessThanEqual implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value <= right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"greater than",">"}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntGreaterThan implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value > right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"greater than",">"}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntGreaterThan implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value > right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"greater than or equal to",">="}, scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableIntGreaterThanEqual implements DrillSimpleFunc {
-
-        @Param NullableIntHolder left;
-        @Param NullableIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value >= right.value) ? 1 : 0;
-            }
-        }
-    }
-
-    @FunctionTemplate(names = {"greater than or equal to",">="},
-                      scope = FunctionTemplate.FunctionScope.SIMPLE)
-    public static class NullableBigIntGreaterThanEqual implements DrillSimpleFunc {
-
-        @Param NullableBigIntHolder left;
-        @Param NullableBigIntHolder right;
-        @Output BitHolder out;
-
-        public void setup(RecordBatch b) {}
-
-        public void eval() {
-            if (left.isSet  == 0 || right.isSet == 0) {
-                out.value = 0;
-            } else {
-                out.value = (left.value >= right.value) ? 1 : 0;
-            }
-        }
-    }
-}
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/TopN/TopNBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/TopN/TopNBatch.java
index 9829fc616..a73bdad9f 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/TopN/TopNBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/TopN/TopNBatch.java
@@ -61,6 +61,7 @@ import org.apache.drill.exec.record.selection.SelectionVector4;
 import org.apache.drill.exec.vector.ValueVector;
 import org.apache.drill.exec.vector.complex.AbstractContainerVector;
 import org.eigenbase.rel.RelFieldCollation.Direction;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 import com.google.common.base.Stopwatch;
 import com.google.common.collect.Lists;
@@ -324,7 +325,9 @@ public class TopNBatch extends AbstractRecordBatch<TopN> {
       g.setMappingSet(mainMapping);
 
       // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      LogicalExpression fh =
+        FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                       context.getFunctionRegistry());
       HoldingContainer out = g.addExpr(fh, false);
       JConditional jc = g.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/StreamingAggBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/StreamingAggBatch.java
index 860627d9c..4acf3d6de 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/StreamingAggBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/aggregate/StreamingAggBatch.java
@@ -248,7 +248,9 @@ public class StreamingAggBatch extends AbstractRecordBatch<StreamingAggregate> {
       cg.setMappingSet(IS_SAME_I2);
       HoldingContainer second = cg.addExpr(expr, false);
 
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(first, second, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper
+          .getOrderingComparatorNullsHigh(first, second, context.getFunctionRegistry());
       HoldingContainer out = cg.addExpr(fh, false);
       cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)))._then()._return(JExpr.FALSE);
     }
@@ -269,7 +271,9 @@ public class StreamingAggBatch extends AbstractRecordBatch<StreamingAggregate> {
       cg.setMappingSet(ISA_B2);
       HoldingContainer second = cg.addExpr(expr, false);
 
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(first, second, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper
+          .getOrderingComparatorNullsHigh(first, second, context.getFunctionRegistry());
       HoldingContainer out = cg.addExpr(fh, false);
       cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)))._then()._return(JExpr.FALSE);
     }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
index ea196457f..8f921f7f8 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/common/ChainedHashTable.java
@@ -250,8 +250,10 @@ public class ChainedHashTable {
         jc._then()._return(JExpr.FALSE);
       }
 
-      // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression f = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      final LogicalExpression f =
+          FunctionGenerationHelper
+          .getOrderingComparatorNullsHigh(left, right, context.getFunctionRegistry());
+
       HoldingContainer out = cg.addExpr(f, false);
 
       // check if two values are not equal (comparator result != 0)
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinStatus.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinStatus.java
index a7fa5aac8..8dfc8f1ab 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinStatus.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinStatus.java
@@ -72,6 +72,29 @@ public final class JoinStatus {
     this.joinType = output.getJoinType();
   }
 
+  @Override
+  public String toString() {
+    return
+        super.toString()
+        + "["
+        + "leftPosition = " + leftPosition
+        + ", rightPosition = " + rightPosition
+        + ", svRightPosition = " + svRightPosition
+        + ", outputPosition = " + outputPosition
+        + ", lastLeft = " + lastLeft
+        + ", lastRight = " + lastRight
+        + ", rightSourceMode = " + rightSourceMode
+        + ", sv4 = " + sv4
+        + ", joinType = " + joinType
+        + ", ok = " + ok
+        + ", initialSet = " + initialSet
+        + ", leftRepeating = " + leftRepeating
+        + ", left = " + left
+        + ", right = " + right
+        + ", outputBatch = " + outputBatch
+        + "]";
+  }
+
   private final IterOutcome nextLeft() {
     return outputBatch.next(LEFT_INPUT, left);
   }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinTemplate.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinTemplate.java
index 48a0996c5..4124e6db5 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinTemplate.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/JoinTemplate.java
@@ -155,7 +155,9 @@ public abstract class JoinTemplate implements JoinWorker {
           }
           status.advanceRight();
 
-        } while ((!status.isLeftRepeating() || status.isRightPositionInCurrentBatch()) && status.isRightPositionAllowed() && doCompare(status.getLeftPosition(), status.getRightPosition()) == 0);
+        } while ((!status.isLeftRepeating() || status.isRightPositionInCurrentBatch())
+                 && status.isRightPositionAllowed()
+                 && doCompare(status.getLeftPosition(), status.getRightPosition()) == 0);
 
         if (status.getRightPosition() > initialRightPosition &&
             (status.isLeftRepeating() || ! status.isNextLeftPositionInCurrentBatch())) {
@@ -204,8 +206,8 @@ public abstract class JoinTemplate implements JoinWorker {
   /**
    * Copy the data to the new record batch (if it fits).
    *
-   * @param leftIndex  position of batch (lower 16 bits) and record (upper 16 bits) in left SV4
-   * @param outIndex position of the output record batch
+   * @param  leftIndex   position of batch (lower 16 bits) and record (upper 16 bits) in left SV4
+   * @param  outIndex  position of the output record batch
    * @return Whether or not the data was copied.
    */
   public abstract void doCopyLeft(@Named("leftIndex") int leftIndex, @Named("outIndex") int outIndex);
@@ -228,8 +230,8 @@ public abstract class JoinTemplate implements JoinWorker {
 
   /**
    * Compare the current left key to the next left key, if it's within the batch.
-   * @return  0 if both keys are equal
-   *          1 if the keys are not equal
+   * @return  0 if both keys are equal,
+   *          1 if the keys are not equal, and
    *         -1 if there are no more keys in this batch
    */
   protected abstract int doCompareNextLeftKey(@Named("leftIndex") int leftIndex);
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/MergeJoinBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/MergeJoinBatch.java
index 257b93e9e..8fce52ec7 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/MergeJoinBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/join/MergeJoinBatch.java
@@ -313,12 +313,13 @@ public class MergeJoinBatch extends AbstractRecordBatch<MergeJoinPOP> {
 
       // check value equality
 
-      LogicalExpression gh = FunctionGenerationHelper.getComparator(compareThisLeftExprHolder,
-        compareNextLeftExprHolder,
-        context.getFunctionRegistry());
+      LogicalExpression gh =
+          FunctionGenerationHelper.getOrderingComparatorNullsHigh(compareThisLeftExprHolder,
+                                                                  compareNextLeftExprHolder,
+                                                                  context.getFunctionRegistry());
       HoldingContainer out = cg.addExpr(gh, false);
 
-      //If not 0, it means not equal. We return this out value.
+      // If not 0, it means not equal. We return this out value.
       JConditional jc = cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
       jc._then()._return(out.getValue());
     }
@@ -523,12 +524,13 @@ public class MergeJoinBatch extends AbstractRecordBatch<MergeJoinPOP> {
         cg.getSetupBlock().assign(JExpr._this().ref(incomingRecordBatch), JExpr._this().ref(incomingRightRecordBatch));
         ClassGenerator.HoldingContainer compareRightExprHolder = cg.addExpr(materializedRightExpr, false);
 
-        LogicalExpression fh = FunctionGenerationHelper.getComparator(compareLeftExprHolder,
-          compareRightExprHolder,
-          context.getFunctionRegistry());
+        LogicalExpression fh =
+            FunctionGenerationHelper.getOrderingComparatorNullsHigh(compareLeftExprHolder,
+                                                                    compareRightExprHolder,
+                                                                    context.getFunctionRegistry());
         HoldingContainer out = cg.addExpr(fh, false);
 
-        // If not 0, it means not equal. We return this out value.
+        // If not 0, it means not equal.
         // Null compares to Null should returns null (unknown). In such case, we return 1 to indicate they are not equal.
         if (compareLeftExprHolder.isOptional() && compareRightExprHolder.isOptional()
             && ! areNullsEqual) {
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/mergereceiver/MergingRecordBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/mergereceiver/MergingRecordBatch.java
index d78ba8ed4..804671e56 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/mergereceiver/MergingRecordBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/mergereceiver/MergingRecordBatch.java
@@ -76,6 +76,7 @@ import org.apache.drill.exec.vector.CopyUtil;
 import org.apache.drill.exec.vector.FixedWidthVector;
 import org.apache.drill.exec.vector.ValueVector;
 import org.eigenbase.rel.RelFieldCollation.Direction;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 import parquet.Preconditions;
 
@@ -636,7 +637,9 @@ public class MergingRecordBatch extends AbstractRecordBatch<MergingReceiverPOP>
       g.setMappingSet(MAIN_MAPPING);
 
       // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                         context.getFunctionRegistry());
       HoldingContainer out = g.addExpr(fh, false);
       JConditional jc = g.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/orderedpartitioner/OrderedPartitionRecordBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/orderedpartitioner/OrderedPartitionRecordBatch.java
index a06207405..352e7aedf 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/orderedpartitioner/OrderedPartitionRecordBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/orderedpartitioner/OrderedPartitionRecordBatch.java
@@ -70,6 +70,7 @@ import org.apache.drill.exec.vector.AllocationHelper;
 import org.apache.drill.exec.vector.IntVector;
 import org.apache.drill.exec.vector.ValueVector;
 import org.eigenbase.rel.RelFieldCollation.Direction;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
@@ -574,7 +575,10 @@ public class OrderedPartitionRecordBatch extends AbstractRecordBatch<OrderedPart
           new ValueVectorReadExpression(new TypedFieldId(expr.getMajorType(), count++)), false);
       cg.setMappingSet(mainMapping);
 
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      // next we wrap the two comparison sides and add the expression block for the comparison.
+      LogicalExpression fh =
+          FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                         context.getFunctionRegistry());
       ClassGenerator.HoldingContainer out = cg.addExpr(fh, false);
       JConditional jc = cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/sort/SortBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/sort/SortBatch.java
index 19f542302..6f19e91d5 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/sort/SortBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/sort/SortBatch.java
@@ -43,6 +43,7 @@ import org.apache.drill.exec.record.WritableBatch;
 import org.apache.drill.exec.record.selection.SelectionVector2;
 import org.apache.drill.exec.record.selection.SelectionVector4;
 import org.eigenbase.rel.RelFieldCollation.Direction;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 import com.sun.codemodel.JConditional;
 import com.sun.codemodel.JExpr;
@@ -180,7 +181,9 @@ public class SortBatch extends AbstractRecordBatch<Sort> {
       g.setMappingSet(mainMapping);
 
       // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      LogicalExpression fh =
+        FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                       context.getFunctionRegistry());
       HoldingContainer out = g.addExpr(fh, false);
       JConditional jc = g.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/window/StreamingWindowFrameRecordBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/window/StreamingWindowFrameRecordBatch.java
index 26d23f231..87209ebf0 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/window/StreamingWindowFrameRecordBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/window/StreamingWindowFrameRecordBatch.java
@@ -185,7 +185,9 @@ public class StreamingWindowFrameRecordBatch extends AbstractSingleRecordBatch<W
       cg.setMappingSet(ISA_B2);
       ClassGenerator.HoldingContainer second = cg.addExpr(expr, false);
 
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(first, second, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper
+          .getOrderingComparatorNullsHigh(first, second, context.getFunctionRegistry());
       ClassGenerator.HoldingContainer out = cg.addExpr(fh, false);
       cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)))._then()._return(JExpr.FALSE);
     }
@@ -205,7 +207,9 @@ public class StreamingWindowFrameRecordBatch extends AbstractSingleRecordBatch<W
       cg.setMappingSet(IS_SAME_I2);
       ClassGenerator.HoldingContainer second = cg.addExpr(expr, false);
 
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(first, second, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper
+          .getOrderingComparatorNullsHigh(first, second, context.getFunctionRegistry());
       ClassGenerator.HoldingContainer out = cg.addExpr(fh, false);
       cg.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)))._then()._return(JExpr.FALSE);
     }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/ExternalSortBatch.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/ExternalSortBatch.java
index 902666141..f320bbbba 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/ExternalSortBatch.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/ExternalSortBatch.java
@@ -65,6 +65,7 @@ import org.apache.drill.exec.vector.complex.AbstractContainerVector;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
 import org.eigenbase.rel.RelFieldCollation.Direction;
+import org.eigenbase.rel.RelFieldCollation.NullDirection;
 
 import com.google.common.base.Stopwatch;
 import com.google.common.collect.Iterators;
@@ -565,7 +566,9 @@ public class ExternalSortBatch extends AbstractRecordBatch<ExternalSort> {
       g.setMappingSet(mainMapping);
 
       // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                         context.getFunctionRegistry());
       HoldingContainer out = g.addExpr(fh, false);
       JConditional jc = g.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
@@ -612,7 +615,9 @@ public class ExternalSortBatch extends AbstractRecordBatch<ExternalSort> {
       g.setMappingSet(MAIN_MAPPING);
 
       // next we wrap the two comparison sides and add the expression block for the comparison.
-      LogicalExpression fh = FunctionGenerationHelper.getComparator(left, right, context.getFunctionRegistry());
+      LogicalExpression fh =
+          FunctionGenerationHelper.getOrderingComparator(od.nullsSortHigh(), left, right,
+                                                         context.getFunctionRegistry());
       HoldingContainer out = g.addExpr(fh, false);
       JConditional jc = g.getEvalBlock()._if(out.getValue().ne(JExpr.lit(0)));
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/MSorter.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/MSorter.java
index e80d30903..d97ffc06e 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/MSorter.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/MSorter.java
@@ -24,6 +24,8 @@ import org.apache.drill.exec.ops.FragmentContext;
 import org.apache.drill.exec.record.VectorContainer;
 import org.apache.drill.exec.record.selection.SelectionVector4;
 
+// TODO:  Doc.:  What's an MSorter?  A sorter for merge join?  something else?
+// (What's the "M" part?  Actually, rename interface to clearer.
 public interface MSorter {
   public void setup(FragmentContext context, BufferAllocator allocator, SelectionVector4 vector4, VectorContainer hyperBatch) throws SchemaChangeException;
   public void sort(VectorContainer container);
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ProjectPrule.java b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ProjectPrule.java
index 732a34520..72034ed85 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ProjectPrule.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ProjectPrule.java
@@ -115,7 +115,7 @@ public class ProjectPrule extends Prule {
 
     for ( RelFieldCollation field : src.getFieldCollations()) {
       if (inToOut.containsKey(field.getFieldIndex())) {
-        newFields.add(new RelFieldCollation(inToOut.get(field.getFieldIndex()), field.getDirection()));
+        newFields.add(new RelFieldCollation(inToOut.get(field.getFieldIndex()), field.getDirection(), field.nullDirection));
       }
     }
 
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/rpc/user/QueryResultHandler.java b/exec/java-exec/src/main/java/org/apache/drill/exec/rpc/user/QueryResultHandler.java
index 9015a162c..b07942873 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/rpc/user/QueryResultHandler.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/rpc/user/QueryResultHandler.java
@@ -65,7 +65,7 @@ public class QueryResultHandler {
     if (l == null) {
       BufferingListener bl = new BufferingListener();
       l = resultsListener.putIfAbsent(result.getQueryId(), bl);
-      // if we had a succesful insert, use that reference.  Otherwise, just throw away the new bufering listener.
+      // if we had a successful insert, use that reference.  Otherwise, just throw away the new bufering listener.
       if (l == null) {
         l = bl;
       }