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https://issues.apache.org/jira/browse/DRILL-7359?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16975894#comment-16975894
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ASF GitHub Bot commented on DRILL-7359:
---------------------------------------
paul-rogers commented on pull request #1870: DRILL-7359: Add support for DICT
type in RowSet Framework
URL: https://github.com/apache/drill/pull/1870#discussion_r347115550
##########
File path:
exec/vector/src/main/java/org/apache/drill/exec/vector/accessor/reader/NullReader.java
##########
@@ -0,0 +1,377 @@
+/*
+ * 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.vector.accessor.reader;
+
+import org.apache.drill.common.types.TypeProtos;
+import org.apache.drill.exec.record.metadata.ColumnMetadata;
+import org.apache.drill.exec.record.metadata.TupleMetadata;
+import org.apache.drill.exec.record.metadata.VariantMetadata;
+import org.apache.drill.exec.vector.accessor.ArrayReader;
+import org.apache.drill.exec.vector.accessor.DictReader;
+import org.apache.drill.exec.vector.accessor.ObjectReader;
+import org.apache.drill.exec.vector.accessor.ObjectType;
+import org.apache.drill.exec.vector.accessor.ScalarReader;
+import org.apache.drill.exec.vector.accessor.TupleReader;
+import org.apache.drill.exec.vector.accessor.ValueType;
+import org.apache.drill.exec.vector.accessor.VariantReader;
+import org.joda.time.Instant;
+import org.joda.time.LocalDate;
+import org.joda.time.LocalTime;
+import org.joda.time.Period;
+
+import java.math.BigDecimal;
+
+/**
+ * Dummy reader which returns {@code null} on access to getters for scalar
types
+ * ({@link #getString()}, {@link #getBytes()} etc.) and itself on access to
reader types
+ * ({@link #scalar()}, {@link #tuple()} etc.). Used when accessing {@link
DictReader} by non-existent key.
+ * {@link #isNull()} returns {@code true}.
+ *
+ * Does not preserve metadata structure. Other methods throw {@link
UnsupportedOperationException}. todo:
+ *
+ * @see DictReader
+ */
+public class NullReader implements ScalarReader, ArrayReader, TupleReader,
VariantReader, ObjectReader, DictReader {
+
+ private static final NullReader INSTANCE = new NullReader();
+
+ public static NullReader instance() {
+ return INSTANCE;
+ }
+
+ @Override
+ public int size() {
+ notSupported("size()");
+ return 0;
+ }
+
+ @Override
+ public ObjectType entryType() {
+ notSupported("entryType()");
+ return null;
+ }
+
+ @Override
+ public ObjectReader entry() {
+ notSupported("entry()");
+ return null;
+ }
+
+ @Override
+ public ScalarReader scalar() {
+ return this;
+ }
+
+ @Override
+ public TupleReader tuple() {
+ return this;
+ }
+
+ @Override
+ public ArrayReader array() {
+ return this;
+ }
+
+ @Override
+ public VariantReader variant() {
+ return this;
+ }
+
+ @Override
+ public DictReader dict() {
+ return this;
+ }
+
+ @Override
+ public void setPosn(int index) {
+ notSupported("setPosn(int)");
+ }
+
+ @Override
+ public void rewind() {
+ notSupported("rewind()");
+ }
Review comment:
This, and the above, are likely to be a problem. The readers recursively
call down the reader tree on operations such as set position or rewind. If this
reader appears in the tree, the whole operation will fail, which is not quite
what we want.
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> Add support for DICT type in RowSet Framework
> ---------------------------------------------
>
> Key: DRILL-7359
> URL: https://issues.apache.org/jira/browse/DRILL-7359
> Project: Apache Drill
> Issue Type: New Feature
> Reporter: Bohdan Kazydub
> Assignee: Bohdan Kazydub
> Priority: Major
> Fix For: 1.17.0
>
>
> Add support for new DICT data type (see DRILL-7096) in RowSet Framework
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