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https://issues.apache.org/jira/browse/DRILL-7278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16857296#comment-16857296
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ASF GitHub Bot commented on DRILL-7278:
---------------------------------------
paul-rogers commented on pull request #1797: DRILL-7278: Refactor result set
loader projection mechanism
URL: https://github.com/apache/drill/pull/1797#discussion_r291011884
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/project/projSet/ProjectedReadColumn.java
##########
@@ -0,0 +1,78 @@
+/*
+ * 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.impl.scan.project.projSet;
+
+import org.apache.drill.exec.physical.rowSet.ProjectionSet;
+import org.apache.drill.exec.physical.rowSet.project.ProjectionType;
+import
org.apache.drill.exec.physical.rowSet.project.RequestedTuple.RequestedColumn;
+import org.apache.drill.exec.record.metadata.ColumnMetadata;
+import org.apache.drill.exec.vector.accessor.convert.ColumnConversionFactory;
+
+/**
+ * Projected column. Includes at least the reader schema. May also
+ * include projection specification, and output schema and a type
+ * conversion.
+ */
+
+public class ProjectedReadColumn extends AbstractReadColProj {
+ private final RequestedColumn requestedCol;
+ private final ColumnMetadata outputSchema;
+ private final ColumnConversionFactory conversionFactory;
+
+ public ProjectedReadColumn(ColumnMetadata readSchema) {
+ this(readSchema, null, null, null);
+ }
+
+ public ProjectedReadColumn(ColumnMetadata readSchema,
+ RequestedColumn requestedCol) {
+ this(readSchema, requestedCol, null, null);
+ }
+
+ public ProjectedReadColumn(ColumnMetadata readSchema,
+ ColumnMetadata outputSchema, ColumnConversionFactory conversionFactory) {
+ this(readSchema, null, outputSchema, null);
+ }
+
+ public ProjectedReadColumn(ColumnMetadata readSchema,
+ RequestedColumn requestedCol, ColumnMetadata outputSchema,
+ ColumnConversionFactory conversionFactory) {
+ super(readSchema);
+ this.requestedCol = requestedCol;
+ this.outputSchema = outputSchema;
+ this.conversionFactory = conversionFactory;
+ }
+
+ @Override
+ public ColumnMetadata providedSchema() {
+ return outputSchema == null ? readSchema : outputSchema;
+ }
+
+ @Override
+ public ProjectionSet mapProjection() {
+ // Should never occur: maps should use the map class.
+ return null;
Review comment:
In general, the caller is aware if this is a map column or not. Returning
null seems a benign way to say, "hey, this isn't a map."
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> Refactor result set loader projection mechanism
> -----------------------------------------------
>
> Key: DRILL-7278
> URL: https://issues.apache.org/jira/browse/DRILL-7278
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.16.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Major
> Fix For: 1.17.0
>
>
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