DRILL-4185: UNION ALL involving empty directory on any side of union all results in Failed query

closes #1083

1 files changed, 94 insertions, 0 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/SchemalessScan.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/SchemalessScan.java
new file mode 100644
index 000000000..e0db1aeb6
--- /dev/null
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/SchemalessScan.java
@@ -0,0 +1,94 @@
+/*
+ * 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.physical.base;
+
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import com.google.common.base.Preconditions;
+import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.common.expression.SchemaPath;
+import org.apache.drill.exec.physical.PhysicalOperatorSetupException;
+import org.apache.drill.exec.planner.logical.DynamicDrillTable;
+import org.apache.drill.exec.proto.CoordinationProtos;
+
+import java.util.List;
+
+/**
+ *  The type of scan operator, which allows to scan schemaless tables ({@link DynamicDrillTable} with null selection)
+ */
+@JsonTypeName("schemaless-scan")
+public class SchemalessScan extends AbstractFileGroupScan implements SubScan {
+
+  private final String selectionRoot;
+
+  public SchemalessScan(String userName, String selectionRoot) {
+    super(userName);
+    this.selectionRoot = selectionRoot;
+  }
+
+  public SchemalessScan(final SchemalessScan that) {
+    super(that);
+    this.selectionRoot = that.selectionRoot;
+  }
+
+  @Override
+  public void applyAssignments(List<CoordinationProtos.DrillbitEndpoint> endpoints) throws PhysicalOperatorSetupException {
+  }
+
+  @Override
+  public SubScan getSpecificScan(int minorFragmentId) throws ExecutionSetupException {
+    return this;
+  }
+
+  @Override
+  public int getMaxParallelizationWidth() {
+    return 1;
+  }
+
+  @Override
+  public String getDigest() {
+    return toString();
+  }
+
+  @Override
+  public String toString() {
+    final String pattern = "SchemalessScan [selectionRoot = %s]";
+    return String.format(pattern, selectionRoot);
+  }
+
+  @Override
+  public PhysicalOperator getNewWithChildren(List<PhysicalOperator> children) throws ExecutionSetupException {
+    Preconditions.checkArgument(children.isEmpty());
+    assert children == null || children.isEmpty();
+    return new SchemalessScan(this);
+  }
+
+  @Override
+  public GroupScan clone(List<SchemaPath> columns) {
+    return this;
+  }
+
+  @Override
+  public ScanStats getScanStats() {
+    return ScanStats.ZERO_RECORD_TABLE;
+  }
+
+  @Override
+  public boolean supportsPartitionFilterPushdown() {
+    return false;
+  }
+
+}