org.apache.parquet.cli.commands.CatCommand.java Source code

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Here is the source code for org.apache.parquet.cli.commands.CatCommand.java

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/*
 * 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.parquet.cli.commands;

import com.beust.jcommander.Parameter;
import com.beust.jcommander.Parameters;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.io.Closeables;
import org.apache.avro.Schema;
import org.apache.parquet.cli.BaseCommand;
import org.apache.parquet.cli.util.Expressions;
import org.slf4j.Logger;
import java.io.Closeable;
import java.io.IOException;
import java.util.List;

import static org.apache.parquet.cli.util.Expressions.select;

@Parameters(commandDescription = "Print the first N records from a file")
public class CatCommand extends BaseCommand {

    @Parameter(description = "<file>")
    List<String> sourceFiles;

    @Parameter(names = { "-n", "--num-records" }, description = "The number of records to print")
    long numRecords;

    @Parameter(names = { "-c", "--column", "--columns" }, description = "List of columns")
    List<String> columns;

    public CatCommand(Logger console, long defaultNumRecords) {
        super(console);
        this.numRecords = defaultNumRecords;
    }

    @Override
    public int run() throws IOException {
        Preconditions.checkArgument(sourceFiles != null && !sourceFiles.isEmpty(), "Missing file name");
        Preconditions.checkArgument(sourceFiles.size() == 1, "Only one file can be given");

        final String source = sourceFiles.get(0);

        Schema schema = getAvroSchema(source);
        Schema projection = Expressions.filterSchema(schema, columns);

        Iterable<Object> reader = openDataFile(source, projection);
        boolean threw = true;
        long count = 0;
        try {
            for (Object record : reader) {
                if (numRecords > 0 && count >= numRecords) {
                    break;
                }
                if (columns == null || columns.size() != 1) {
                    console.info(String.valueOf(record));
                } else {
                    console.info(String.valueOf(select(projection, record, columns.get(0))));
                }
                count += 1;
            }
            threw = false;
        } catch (RuntimeException e) {
            throw new RuntimeException("Failed on record " + count, e);
        } finally {
            if (reader instanceof Closeable) {
                Closeables.close((Closeable) reader, threw);
            }
        }

        return 0;
    }

    @Override
    public List<String> getExamples() {
        return Lists.newArrayList("# Show the first 10 records in file \"data.avro\":", "data.avro",
                "# Show the first 50 records in file \"data.parquet\":", "data.parquet -n 50");
    }
}