如何将数据帧(从配置单元表中获得)写入hadoop SequenceFile和RCFile?

问题描述

我能够将其写入

• ORC

PARQUET

直接和

TEXTFILE

AVRO

使用数据块中的其他依赖项.

using additional dependencies from databricks.

    <dependency>
        <groupId>com.databricks</groupId>
        <artifactId>spark-csv_2.10</artifactId>
        <version>1.5.0</version>
    </dependency>
    <dependency>
        <groupId>com.databricks</groupId>
        <artifactId>spark-avro_2.10</artifactId>
        <version>2.0.1</version>
    </dependency>

示例代码:

    SparkContext sc = new SparkContext(conf);
    HiveContext hc = new HiveContext(sc);
    DataFrame df = hc.table(hiveTableName);
    df.printSchema();
    DataFrameWriter writer = df.repartition(1).write();

    if ("ORC".equalsIgnoreCase(hdfsFileFormat)) {
        writer.orc(outputHdfsFile);

    } else if ("PARQUET".equalsIgnoreCase(hdfsFileFormat)) {
        writer.parquet(outputHdfsFile);

    } else if ("TEXTFILE".equalsIgnoreCase(hdfsFileFormat)) {
        writer.format("com.databricks.spark.csv").option("header", "true").save(outputHdfsFile);

    } else if ("AVRO".equalsIgnoreCase(hdfsFileFormat)) {
        writer.format("com.databricks.spark.avro").save(outputHdfsFile);
    }

有什么方法可以将数据帧写入hadoop SequenceFile和RCFile吗?

Is there any way to write dataframe into hadoop SequenceFile and RCFile?

推荐答案

您可以使用void saveAsObjectFile(String path)将RDD保存为序列化对象的SequenceFile.因此，在您的情况下，您必须从DataFrame中检索RDD:

You can use void saveAsObjectFile(String path) to save a RDD as a SequenceFile of serialized objects. So in your case you have to to retrieve the RDD from the DataFrame:

JavaRDD<Row> rdd = df.javaRDD;
rdd.saveAsObjectFile(outputHdfsFile);

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