Scala Spark结构化流错误

我正在尝试执行以下代码：

import org.apache.spark.sql.types._

val schema = StructType(
StructField("id", LongType, false) ::
StructField("name", StringType, true) ::
StructField("city", StringType, true) :: Nil)


case class Person(id: Long, name: String, city: String)

import org.apache.spark.sql.Encoders

val schema = Encoders.product[Person].schema


val people = spark.readStream.schema(schema).csv("/data/pncdw/scratch/test/*.csv").as[Person]

val population = people.groupBy('city).agg(count('city) as "population")

import scala.concurrent.duration._

import org.apache.spark.sql.streaming.{OutputMode, Trigger}

val populationStream = population.
writeStream.
format("console").
trigger(Trigger.ProcessingTime(30.seconds)).
outputMode(OutputMode.Complete).
queryName("textStream").start

但我得到了这个错误：

ERROR : scala> populationStream.trigger(Trigger.once)
<console>:43: error: not found: value Trigger
populationStream.trigger(Trigger.once)

---

触发器

是的属性

您在

populationStream

上调用它，这是

StreamingQuery

从

start

方法返回的

如果要为查询设置，请替换现有查询：

val populationStream = population.
  writeStream.
  format("console").
  trigger(Trigger.Once).
  outputMode(OutputMode.Complete).
  queryName("textStream").start

---

它是

Trigger.Once

而不是

Trigger.Once

。已更正。但还是一样error@user9830431很抱歉，din get it.follow是apache库中的一个示例，在我的示例中不起作用，尽管Scala示例是：df.writeStream.trigger（ProcessingTime（“10秒”））

val populationStream = population.
  writeStream.
  format("console").
  trigger(Trigger.Once).
  outputMode(OutputMode.Complete).
  queryName("textStream").start