Github user mgaido91 commented on a diff in the pull request:

    https://github.com/apache/spark/pull/18329#discussion_r123445514
  
    --- Diff: 
sql/core/src/main/scala/org/apache/spark/sql/streaming/DataStreamWriter.scala 
---
    @@ -264,12 +281,12 @@ final class DataStreamWriter[T] private[sql](ds: 
Dataset[T]) {
             df,
             sink,
             outputMode,
    -        useTempCheckpointLocation = true,
    +        useTempCheckpointLocation = isTempCheckpointLocationAvailable,
             trigger = trigger)
         } else {
           val (useTempCheckpointLocation, recoverFromCheckpointLocation) =
             if (source == "console") {
    -          (true, false)
    +          (isTempCheckpointLocationAvailable, false)
    --- End diff --
    
    Well, actually I don't think "java.io.tmpdir" will ever be on a filesystem 
different from the local one. But, the other PR forces the metadata to be 
written on the local filesystem, despite the default one is different (for 
instance it can be HDFS).
    This means that in a distributed environment, which should be fault 
tolerant, with that patch  if a node fails we loose the metadata. Since one of 
the involved sink is the `foreach` one, which can be used to write the data 
somewhere (for example HBase or Kafka), I think that forcing the user to 
specify a `checkpointLocation` which is created on the `defaultFs` (in this 
case HDFS) would be a better option.


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