apache-spark - 如何将数据框中的 org.apache.spark.mllib.linalg.Vector 保存到 cassandra

Question

我需要在其中一个列中保存包含 org.apache.spark.mllib.linalg.Vector 的数据框。从数据帧在 cassandra 中创建表时，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

如果要保存此类型的二进制值，只需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，您需要对 Scala 集合进行适当的转换。