FetchParquet.java

/*
 * 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
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package org.apache.nifi.processors.parquet;

import org.apache.avro.generic.GenericRecord;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.nifi.annotation.behavior.InputRequirement;
import org.apache.nifi.annotation.behavior.Restricted;
import org.apache.nifi.annotation.behavior.SupportsBatching;
import org.apache.nifi.annotation.behavior.WritesAttribute;
import org.apache.nifi.annotation.behavior.WritesAttributes;
import org.apache.nifi.annotation.documentation.CapabilityDescription;
import org.apache.nifi.annotation.documentation.SeeAlso;
import org.apache.nifi.annotation.documentation.Tags;
import org.apache.nifi.flowfile.FlowFile;
import org.apache.nifi.processor.ProcessContext;
import org.apache.nifi.processors.hadoop.AbstractFetchHDFSRecord;
import org.apache.nifi.processors.hadoop.record.HDFSRecordReader;
import org.apache.nifi.processors.parquet.record.AvroParquetHDFSRecordReader;
import org.apache.parquet.avro.AvroParquetReader;
import org.apache.parquet.hadoop.ParquetReader;

import java.io.IOException;

@SupportsBatching
@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
@Tags({"parquet", "hadoop", "HDFS", "get", "ingest", "fetch", "source", "restricted"})
@CapabilityDescription("Reads from a given Parquet file and writes records to the content of the flow file using " +
        "the selected record writer. The original Parquet file will remain unchanged, and the content of the flow file " +
        "will be replaced with records of the selected type. This processor can be used with ListHDFS or ListFile to obtain " +
        "a listing of files to fetch.")
@WritesAttributes({
        @WritesAttribute(attribute="fetch.failure.reason", description="When a FlowFile is routed to 'failure', this attribute is added " +
                "indicating why the file could not be fetched from the given filesystem."),
        @WritesAttribute(attribute = "record.count", description = "The number of records in the resulting flow file")
})
@SeeAlso({PutParquet.class})
@Restricted("Provides operator the ability to retrieve any file that NiFi has access to in HDFS or the local filesystem.")
public class FetchParquet extends AbstractFetchHDFSRecord {

    @Override
    public HDFSRecordReader createHDFSRecordReader(final ProcessContext context, final FlowFile flowFile, final Configuration conf, final Path path)
            throws IOException {
        final ParquetReader.Builder<GenericRecord> readerBuilder = AvroParquetReader.<GenericRecord>builder(path).withConf(conf);
        return new AvroParquetHDFSRecordReader(readerBuilder.build());
    }

}