apache-spark – 如何在Spark的Cassandra查询中使用java.time.LocalDate？

2023年4月26日 357次阅读

我们在Cassandra中有一个表,其start_time列为date类型.

当我们执行以下代码时：

val resultRDD = inputRDD.joinWithCassandraTable(KEY_SPACE,TABLE)
   .where("start_time = ?", java.time.LocalDate.now)

我们收到以下错误：

com.datastax.spark.connector.types.TypeConversionException: Cannot convert object 2016-10-13 of type class java.time.LocalDate to com.datastax.driver.core.LocalDate.
at com.datastax.spark.connector.types.TypeConverter$$anonfun$convert$1.apply(TypeConverter.scala:45)
at com.datastax.spark.connector.types.TypeConverter$$anonfun$convert$1.apply(TypeConverter.scala:43)
at com.datastax.spark.connector.types.TypeConverter$LocalDateConverter$$anonfun$convertPF$14.applyOrElse(TypeConverter.scala:449)
at com.datastax.spark.connector.types.TypeConverter$class.convert(TypeConverter.scala:43)
at com.datastax.spark.connector.types.TypeConverter$LocalDateConverter$.com$datastax$spark$connector$types$NullableTypeConverter$$super$convert(TypeConverter.scala:439)
at com.datastax.spark.connector.types.NullableTypeConverter$class.convert(TypeConverter.scala:56)
at com.datastax.spark.connector.types.TypeConverter$LocalDateConverter$.convert(TypeConverter.scala:439)
at com.datastax.spark.connector.types.TypeConverter$OptionToNullConverter$$anonfun$convertPF$29.applyOrElse(TypeConverter.scala:788)
at com.datastax.spark.connector.types.TypeConverter$class.convert(TypeConverter.scala:43)
at com.datastax.spark.connector.types.TypeConverter$OptionToNullConverter.com$datastax$spark$connector$types$NullableTypeConverter$$super$convert(TypeConverter.scala:771)
at com.datastax.spark.connector.types.NullableTypeConverter$class.convert(TypeConverter.scala:56)
at com.datastax.spark.connector.types.TypeConverter$OptionToNullConverter.convert(TypeConverter.scala:771)
at com.datastax.spark.connector.writer.BoundStatementBuilder$$anonfun$8.apply(BoundStatementBuilder.scala:93)

我已经尝试根据documentation注册自定义转换器：

object JavaLocalDateToCassandraLocalDateConverter extends TypeConverter[com.datastax.driver.core.LocalDate] {
  def targetTypeTag = typeTag[com.datastax.driver.core.LocalDate]
  def convertPF = { 
      case ld: java.time.LocalDate => com.datastax.driver.core.LocalDate.fromYearMonthDay(ld.getYear, ld.getMonthValue, ld.getDayOfMonth) 
      case _ => com.datastax.driver.core.LocalDate.fromYearMonthDay(1971, 1, 1) 
  }
}

object CassandraLocalDateToJavaLocalDateConverter extends TypeConverter[java.time.LocalDate] {
  def targetTypeTag = typeTag[java.time.LocalDate]
  def convertPF = { case ld: com.datastax.driver.core.LocalDate => java.time.LocalDate.of(ld.getYear(), ld.getMonth(), ld.getDay()) 
                    case _ => java.time.LocalDate.now 
  }
}

TypeConverter.registerConverter(JavaLocalDateToCassandraLocalDateConverter)
TypeConverter.registerConverter(CassandraLocalDateToJavaLocalDateConverter)

但它没有帮助.

如何在从Spark执行的Cassandra查询中使用JDK8 Date / Time类？

最佳答案 我认为在这样的where子句中最简单的事情就是调用

sc
 .cassandraTable("test","test")
 .where("start_time = ?", java.time.LocalDate.now.toString)
 .collect`

然后传入字符串,因为这将是一个定义良好的转换.

TypeConverters中似乎存在一个问题,即转换器不优先于内置转换器.我快点看看.

– 编辑 –

似乎已注册的转换器未正确传输到执行程序.在本地模式下,代码按预期工作,这使我认为这是一个序列化问题.我会在Spark Cassandra Connector上打开这个问题的票.

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