Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1112#discussion_r168681135
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/record/metadata/AbstractColumnMetadata.java
---
@@ -0,0 +1,206 @@
+/*
+ * 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.record.metadata;
+
+import org.apache.drill.common.types.TypeProtos.DataMode;
+import org.apache.drill.common.types.TypeProtos.MajorType;
+import org.apache.drill.common.types.TypeProtos.MinorType;
+import org.apache.drill.exec.record.MaterializedField;
+
+/**
+ * Abstract definition of column metadata. Allows applications to create
+ * specialized forms of a column metadata object by extending from this
+ * abstract class.
+ * <p>
+ * Note that, by design, primitive columns do not have a link to their
+ * tuple parent, or their index within that parent. This allows the same
+ * metadata to be shared between two views of a tuple, perhaps physical
+ * and projected views. This restriction does not apply to map columns,
+ * since maps (and the row itself) will, by definition, differ between
+ * the two views.
+ */
+
+public abstract class AbstractColumnMetadata implements ColumnMetadata {
+
+ // Capture the key schema information. We cannot use the
MaterializedField
+ // or MajorType because then encode child information that we encode here
+ // as a child schema. Keeping the two in sync is nearly impossible.
+
+ protected final String name;
+ protected final MinorType type;
+ protected final DataMode mode;
+ protected final int precision;
+ protected final int scale;
+ protected boolean projected = true;
+
--- End diff --
AFAIK, we do not support the time-zone aware data types at present.
---
