将数据从BigQuery导出到Google Storage的最佳方式是什么？请注意，我需要对BigQuery运行查询，而不是导出所有数据。本质上，我需要对BigQuery运行自定义查询（如select*from mytable where code=foo），查询的结果需要写入csv，存储在Google Cloud上。我相信，最好的方法是通过Google数据流。让我知道是否有其他选择？此外，我正在寻找一些关于如何完成此操作的示例。有什么地方可以找到一些示例吗？

这是我到目前为止所拥有的PipelineOptions PipelineOptions=PipelineOptionsFactory. create（）；管道p=Pipeline.create（Pipeline Options）；

    Date date = new Date();

    p.getOptions().setTempLocation("gs://mybucket/tmp"+date.getTime());

    PCollection<TableRow> rowPCollection = p.apply(BigQueryIO.Read.named("promos")
            .fromQuery("SELECT * FROM [projectid:mydataset.mytable] where id = 256 LIMIT 1000"));

    PCollection<String> stringPCollection = rowPCollection.apply(ParDo.named("Extract").of(new DoFn<TableRow, String>() {
        @Override
        public void processElement(ProcessContext c) {
            TableRow tableRow = c.element();
            try {
                String prettyString = tableRow.toPrettyString();
                c.output(prettyString);
            } catch (IOException e) {
                log.error("Exception occurred:" + e.getMessage());
            }
        }
    }));

    stringPCollection.apply(TextIO.Write.named("WriteOutput").to("gs://mybucket/avexport").withSuffix(".csv"));

    p.run();

当此运行时，在创建ParDo时会抛出异常

caused by: java.io.NotSerializableException: com.my.validation.CommonValidator
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at com.google.cloud.dataflow.sdk.util.SerializableUtils.serializeToByteArray(SerializableUtils.java:50)