| /* |
| * 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.metastore.iceberg.operate; |
| |
| import org.apache.drill.metastore.MetastoreColumn; |
| import org.apache.drill.metastore.iceberg.IcebergMetastoreContext; |
| import org.apache.drill.metastore.iceberg.transform.FilterTransformer; |
| import org.apache.drill.metastore.operate.AbstractRead; |
| import org.apache.drill.metastore.operate.MetadataTypeValidator; |
| import org.apache.drill.metastore.operate.Read; |
| import com.google.common.collect.Lists; |
| import org.apache.iceberg.data.IcebergGenerics; |
| import org.apache.iceberg.data.Record; |
| import org.apache.iceberg.expressions.Expression; |
| import org.apache.iceberg.types.Types; |
| |
| import java.util.List; |
| |
| /** |
| * Implementation of {@link Read} interface based on {@link AbstractRead} parent class. |
| * Reads information from Iceberg table based on given filter expression. |
| * Supports reading information for specific columns. |
| * |
| * @param <T> Metastore component unit type |
| */ |
| public class IcebergRead<T> extends AbstractRead<T> { |
| |
| private final IcebergMetastoreContext<T> context; |
| private final String[] defaultColumns; |
| |
| public IcebergRead(MetadataTypeValidator metadataTypeValidator, IcebergMetastoreContext<T> context) { |
| super(metadataTypeValidator); |
| this.context = context; |
| this.defaultColumns = context.table().schema().columns().stream() |
| .map(Types.NestedField::name) |
| .toArray(String[]::new); |
| } |
| |
| @Override |
| protected List<T> internalExecute() { |
| String[] selectedColumns = columns.isEmpty() |
| ? defaultColumns |
| : columns.stream() |
| .map(MetastoreColumn::columnName) |
| .toArray(String[]::new); |
| |
| FilterTransformer filterTransformer = context.transformer().filter(); |
| Expression rowFilter = filterTransformer.combine( |
| filterTransformer.transform(metadataTypes), filterTransformer.transform(filter)); |
| |
| Iterable<Record> records = IcebergGenerics.read(context.table()) |
| .select(selectedColumns) |
| .where(rowFilter) |
| .build(); |
| |
| return context.transformer().outputData() |
| .columns(selectedColumns) |
| .records(Lists.newArrayList(records)) |
| .execute(); |
| } |
| } |