arina-ielchiieva commented on a change in pull request #1797: DRILL-7278: Refactor result set loader projection mechanism URL: https://github.com/apache/drill/pull/1797#discussion_r289938759
########## 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); + break; + default: + throw new IllegalStateException(projType.toString()); Review comment: Please add to the error message: "Unexpected projection type: " ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services