DRILL-1973: Filter should check for record count before doing evaluation. Fixes NPE.

3 files changed, 20 insertions, 0 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate2.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate2.java
index 7e0dd657c..26f265782 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate2.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate2.java
@@ -60,6 +60,9 @@ public abstract class FilterTemplate2 implements Filterer{
   }
 
   public void filterBatch(int recordCount){
+    if (recordCount == 0) {
+      return;
+    }
     if (! outgoingSelectionVector.allocateNew(recordCount)) {
       throw new UnsupportedOperationException("Unable to allocate filter batch");
     }
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate4.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate4.java
index 0ea53ac58..fd1f9e68c 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate4.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/filter/FilterTemplate4.java
@@ -43,6 +43,9 @@ public abstract class FilterTemplate4 implements Filterer {
 
   @Override
   public void filterBatch(int recordCount){
+    if (recordCount == 0) {
+      return;
+    }
     int outPos = 0;
     for (int i = 0; i < incomingSelectionVector.getCount(); i++) {
       int index = incomingSelectionVector.get(i);
diff --git a/exec/java-exec/src/test/java/org/apache/drill/TestExampleQueries.java b/exec/java-exec/src/test/java/org/apache/drill/TestExampleQueries.java
index f740a1c6f..a3b5ff19b 100644
--- a/exec/java-exec/src/test/java/org/apache/drill/TestExampleQueries.java
+++ b/exec/java-exec/src/test/java/org/apache/drill/TestExampleQueries.java
@@ -504,4 +504,18 @@ public class TestExampleQueries extends BaseTestQuery{
     assertEquals(expectedRecordCount, actualRecordCount);
   }
 
+  @Test // DRILL-1973
+  public void testLimit0SubqueryWithFilter() throws Exception {
+    String query1 = "select * from (select sum(1) as x from  cp.`tpch/region.parquet` limit 0) WHERE x < 10";
+    String query2 = "select * from (select sum(1) as x from  cp.`tpch/region.parquet` limit 0) WHERE (0 = 1)";
+    int actualRecordCount = 0;
+    int expectedRecordCount = 0;
+
+    actualRecordCount = testSql(query1);
+    assertEquals(expectedRecordCount, actualRecordCount);
+
+    actualRecordCount = testSql(query2);
+    assertEquals(expectedRecordCount, actualRecordCount);
+  }
+
 }