Read and Write Tables From Hive With Spark Scala

How to read and write tables from Hive with Spark Scala.

  1. Install the following sbt (Scala Build Tool) dependencies:

    libraryDependencies += "org.apache.spark" %% "spark-core" % "2.4.0" % "provided"
    libraryDependencies += "org.apache.spark" %% "spark-sql" % "2.4.0" % "provided"

    As the Spark Scala dependencies already exist in Saagie, they are specified as "provided" to avoid having a heavy JAR file.

  2. Create your Spark session by running the following lines of code:

    // Initialize a Spark session with Hive support enabled and configures it to connect to a Hive Metastore.
    val sparkSession = SparkSession.builder()
     .config("hive.metastore.warehouse.dir", params.hiveHost + "user/hive/warehouse")
  3. You can now read and write tables from Hive by running the following lines of code:

    • Read Tables

    • Write Tables

    // Read tables
    // Read Hive tables in a Spark DataFrame.
    val dfHive = sql("SELECT * from helloworld")"Reading hive table : OK")
    // Create a DataFrame with 1 partition.
    import sparkSession.implicits._
    val df = Seq(HelloWorld("helloworld")).toDF().coalesce(1)
    // Write tables
    // Write the DataFrame as a Hive table.
    import sparkSession.sql
    sql("DROP TABLE IF EXISTS helloworld")
    sql("CREATE TABLE helloworld (message STRING)")
    //Log the successful message."Writing hive table : OK")