为什么id和runId在流查询的每次开始都会更改?

id 和 runId .

为什么当我 stop start

// Reading datasets with records from a Kafka topic
val idsPerBatch = spark.
  readStream.
  format("kafka").
  option("subscribe", "topic1").
  option("kafka.bootstrap.servers", "localhost:9092").
  load.
  withColumn("tokens", split('value, ",")).
  withColumn("seconds", 'tokens(0) cast "long").
  withColumn("event_time", to_timestamp(from_unixtime('seconds))). // <-- Event time has to be a timestamp
  withColumn("id", 'tokens(1)).
  withColumn("batch", 'tokens(2) cast "int").
  withWatermark(eventTime = "event_time", delayThreshold = "10 seconds"). // <-- define watermark (before groupBy!)
  groupBy($"event_time"). // <-- use event_time for grouping
  agg(collect_list("batch") as "batches", collect_list("id") as "ids").
  withColumn("event_time", to_timestamp($"event_time")) // <-- convert to human-readable date

// start the query and display results to console
import scala.concurrent.duration._
import org.apache.spark.sql.streaming.{OutputMode, Trigger}
val sq = idsPerBatch.
  writeStream.
  format("console").
  option("truncate", false).
  trigger(Trigger.ProcessingTime(5.seconds)).
  outputMode(OutputMode.Append). // <-- Append output mode
  start