We use struct streaming 2.2, when sinking as csv, a json str will automatic
add "" for it, like an element is
>
> {"hello": "world"}
result data in fs will be
> "{\"hello\": \"world\"}"
How to avoid the "",we only want
> {"hello": "world"}
code like
> resultDS.
> writeStream.
> outputMode(OutputMode.Append()).
> trigger(Trigger.ProcessingTime(TriggerInterval, TimeUnit.SECONDS)).
> format("csv").
> option("sep", "\t").
> option("path", DIR).
> option("checkpointLocation", CheckPointDir).
> option("compression", "gzip").
> partitionBy("event_day", "event_hour").
> start.
> awaitTermination()
>
