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https://issues.apache.org/jira/browse/DRILL-7278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16854847#comment-16854847
]
ASF GitHub Bot commented on DRILL-7278:
---------------------------------------
arina-ielchiieva commented on pull request #1797: DRILL-7278: Refactor result
set loader projection mechanism
URL: https://github.com/apache/drill/pull/1797#discussion_r289938524
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/project/projSet/ProjectionSetBuilder.java
##########
@@ -0,0 +1,101 @@
+/*
+ * 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 java.util.Collection;
+
+import org.apache.drill.common.exceptions.CustomErrorContext;
+import org.apache.drill.common.expression.SchemaPath;
+import org.apache.drill.exec.physical.rowSet.ProjectionSet;
+import org.apache.drill.exec.physical.rowSet.project.RequestedTuple;
+import
org.apache.drill.exec.physical.rowSet.project.RequestedTuple.TupleProjectionType;
+import org.apache.drill.exec.physical.rowSet.project.RequestedTupleImpl;
+import org.apache.drill.exec.record.metadata.TupleMetadata;
+
+public class ProjectionSetBuilder {
+
+ private RequestedTuple parsedProjection;
+ private TypeConverter typeConverter;
+ private CustomErrorContext errorContext;
+
+ /**
+ * Record (batch) readers often read a subset of available table columns,
+ * but want to use a writer schema that includes all columns for ease of
+ * writing. (For example, a CSV reader must read all columns, even if the
user
+ * wants a subset. The unwanted columns are simply discarded.)
+ * <p>
+ * This option provides a projection list, in the form of column names, for
+ * those columns which are to be projected. Only those columns will be
+ * backed by value vectors; non-projected columns will be backed by "null"
+ * writers that discard all values.
+ *
+ * @param projection the list of projected columns
+ * @return this builder
+ */
+
+ public ProjectionSetBuilder projectionList(Collection<SchemaPath>
projection) {
+ if (projection == null) {
+ parsedProjection = null;
+ } else {
+ parsedProjection = RequestedTupleImpl.parse(projection);
+ }
+ return this;
+ }
+
+ public ProjectionSetBuilder parsedProjection(RequestedTuple projection) {
+ parsedProjection = projection;
+ return this;
+ }
+
+ public ProjectionSetBuilder outputSchema(TupleMetadata schema) {
+ typeConverter = TypeConverter.builder().providedSchema(schema).build();
+ return this;
+ }
+
+ public ProjectionSetBuilder typeConverter(TypeConverter converter) {
+ this.typeConverter = converter;
+ return this;
+ }
+
+ public ProjectionSetBuilder errorContext(CustomErrorContext errorContext) {
+ this.errorContext = errorContext;
+ return this;
+ }
+
+ public ProjectionSet build() {
+ TupleProjectionType projType = parsedProjection == null ?
+ TupleProjectionType.ALL : parsedProjection.type();
+
+ ProjectionSet projSet;
+ switch (projType) {
+ case ALL:
+ projSet = new WildcardProjectionSet(typeConverter);
+ break;
+ case NONE:
+ projSet = ProjectionSetFactory.projectNone();
+ break;
+ case SOME:
+ projSet = new ExplicitProjectionSet(parsedProjection, typeConverter);
Review comment:
```suggestion
projSet = new ExplicitProjectionSet(parsedProjection, typeConverter);
```
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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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