sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/meta/provider/parquet/ParquetTable.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,
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 * See the License for the specific language governing permissions and
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package org.apache.beam.sdk.extensions.sql.meta.provider.parquet;

import java.io.Serializable;
import org.apache.avro.generic.GenericRecord;
import org.apache.beam.sdk.extensions.sql.impl.BeamTableStatistics;
import org.apache.beam.sdk.extensions.sql.meta.BeamSqlTable;
import org.apache.beam.sdk.extensions.sql.meta.SchemaBaseBeamTable;
import org.apache.beam.sdk.io.parquet.ParquetIO;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.schemas.utils.AvroUtils;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.values.PBegin;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PDone;
import org.apache.beam.sdk.values.Row;

/** {@link ParquetTable} is a {@link BeamSqlTable}. */
public class ParquetTable extends SchemaBaseBeamTable implements Serializable {
  private final String filePattern;

  public ParquetTable(Schema beamSchema, String filePattern) {
    super(beamSchema);
    this.filePattern = filePattern;
  }

  @Override
  public PCollection<Row> buildIOReader(PBegin begin) {
    PTransform<PCollection<GenericRecord>, PCollection<Row>> readConverter =
        GenericRecordReadConverter.builder().beamSchema(schema).build();

    return begin
        .apply("ParquetIORead", ParquetIO.read(AvroUtils.toAvroSchema(schema)).from(filePattern))
        .apply("GenericRecordToRow", readConverter);
  }

  @Override
  public PDone buildIOWriter(PCollection<Row> input) {
    throw new UnsupportedOperationException("Writing to a Parquet file is not supported");
  }

  @Override
  public PCollection.IsBounded isBounded() {
    return PCollection.IsBounded.BOUNDED;
  }

  @Override
  public BeamTableStatistics getTableStatistics(PipelineOptions options) {
    return BeamTableStatistics.BOUNDED_UNKNOWN;
  }
}