如何保存org.apache.spark.mllib.linalg.Vector的数据框架到cassandra

Question

我需要保存包含org.apache.spark.mllib.linalg.Vector在其中一列中的数据框架。在cassandra中从数据框创建表时，抛出错误。

java.lang.Exception: Cassandra Writer Failed. java.lang.IllegalArgumentException: Unsupported type: org.apache.spark.mllib.linalg.VectorUDT@f71b0bce
        at com.datastax.spark.connector.types.ColumnType$.unsupportedType$1(ColumnType.scala:132)
        at com.datastax.spark.connector.types.ColumnType$.fromSparkSqlType(ColumnType.scala:155)
        at com.datastax.spark.connector.mapper.DataFrameColumnMapper$$anonfun$1.apply(DataFrameColumnMapper.scala:18)
        at com.datastax.spark.connector.mapper.DataFrameColumnMapper$$anonfun$1.apply(DataFrameColumnMapper.scala:16)
        at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
        at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
        at scala.collection.immutable.List.foreach(List.scala:318)
        at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
        at scala.collection.AbstractTraversable.map(Traversable.scala:105)
        at com.datastax.spark.connector.mapper.DataFrameColumnMapper.newTable(DataFrameColumnMapper.scala:16)
        at com.datastax.spark.connector.cql.TableDef$.fromDataFrame(Schema.scala:206)

Answer 1

如果您想保存这种类型的二进制值，您只需要将其转换为字节数组，然后将其保存到blob列。

如果您想将其保存为一组值，则需要将其转换为Scala集合。