Github user zjffdu commented on a diff in the pull request:
https://github.com/apache/spark/pull/9490#discussion_r44534648
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala ---
@@ -604,10 +609,33 @@ abstract class HadoopFsRelation
private[sql](maybePartitionSpec: Option[Partitio
}
}
- buildInternalScan(requiredColumns, filters, inputStatuses,
broadcastedConf)
+ if (!inputExists) {
+ throw new IOException("Input paths do not exist, input paths="
+ + inputPaths.mkString("[", ",", "]"))
+ } else {
+ if (inputStatuses.isEmpty && readFromHDFS) {
+ logWarning("Input paths are empty, input paths=" +
inputPaths.mkString("[", ",", "]"))
+ sqlContext.sparkContext.emptyRDD[InternalRow]
+ } else {
+ buildInternalScan(requiredColumns, filters, inputStatuses,
broadcastedConf)
+ }
+ }
}
/**
+ * Most of time, HadoopFsRelation should check the inputPaths, but for
some cases it is not,
+ * e.g. JsonRelation may read from RDD[String]
+ */
+ def inputExists: Boolean = fileStatusCache.inputExists
+
+ /**
+ * Most of time, HadoopFsRelation should read from hdfs, but some cases
it is not,
+ * e.g. JsonRelation may read from RDD[String]
+ * @return
+ */
+ def readFromHDFS: Boolean = true
--- End diff --
Agree it's weird for JsonRelation don't read read from hdfs. I have one
suggestion that we can separate the JsonRelation based on RDD input to a new
JsonRDDRelation which don't extend HadoopFsRelation. since JsonRelation is
private, this would not bring incompatibility issue
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