Github user vvysotskyi commented on a diff in the pull request:
https://github.com/apache/drill/pull/1066#discussion_r162161040
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/DrillRelBuilder.java
---
@@ -0,0 +1,69 @@
+/*
+ * 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.planner;
+
+import org.apache.calcite.plan.Context;
+import org.apache.calcite.plan.Contexts;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptSchema;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.RelFactories;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.tools.RelBuilderFactory;
+import org.apache.calcite.util.Util;
+
+public class DrillRelBuilder extends RelBuilder {
+ private final RelFactories.FilterFactory filterFactory;
+
+ protected DrillRelBuilder(Context context, RelOptCluster cluster,
RelOptSchema relOptSchema) {
+ super(context, cluster, relOptSchema);
+ this.filterFactory =
+ Util.first(context.unwrap(RelFactories.FilterFactory.class),
+ RelFactories.DEFAULT_FILTER_FACTORY);
+ }
+
+ /**
+ * Original method {@link RelBuilder#empty} returns empty values rel.
+ * In the order to preserve dara row types, filter with false predicate
is created.
+ */
+ @Override
+ public RelBuilder empty() {
--- End diff --
In some cases, RowType of the input may not be known at the moment when
this method is called (some of the columns or all columns were not dynamically
discovered yet), therefore I had to make changes directly in Calcite to allow
using of custom RelBuilder and make changes in Drill to pass custom RelBuilder
into them. For more details please see [1] and [2].
[1]
https://lists.apache.org/list.html?d...@calcite.apache.org:lte=1y:Make%20RelBuilder.filter%28%29%20configurable
[2] https://issues.apache.org/jira/browse/CALCITE-2043
---
