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[SPARK-25669][SQL] Check CSV header only when it exists #22656

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MaxGekk wants to merge 1 commit into from
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[SPARK-25669][SQL] Check CSV header only when it exists #22656

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7 changes: 5 additions & 2 deletions sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -505,7 +505,8 @@ class DataFrameReader private[sql](sparkSession: SparkSession) extends Logging {
val actualSchema =
StructType(schema.filterNot(_.name == parsedOptions.columnNameOfCorruptRecord))

val linesWithoutHeader: RDD[String] = maybeFirstLine.map { firstLine =>
val linesWithoutHeader = if (parsedOptions.headerFlag && maybeFirstLine.isDefined) {
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@HyukjinKwon HyukjinKwon Oct 9, 2018

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LGTM but it really needs some refactoring. Let me give a shot

val firstLine = maybeFirstLine.get
val parser = new CsvParser(parsedOptions.asParserSettings)
val columnNames = parser.parseLine(firstLine)
CSVDataSource.checkHeaderColumnNames(
Expand All @@ -515,7 +516,9 @@ class DataFrameReader private[sql](sparkSession: SparkSession) extends Logging {
parsedOptions.enforceSchema,
sparkSession.sessionState.conf.caseSensitiveAnalysis)
filteredLines.rdd.mapPartitions(CSVUtils.filterHeaderLine(_, firstLine, parsedOptions))
}.getOrElse(filteredLines.rdd)
} else {
filteredLines.rdd
}

val parsed = linesWithoutHeader.mapPartitions { iter =>
val rawParser = new UnivocityParser(actualSchema, parsedOptions)
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6 changes: 6 additions & 0 deletions sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala
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Expand Up @@ -1820,4 +1820,10 @@ class CSVSuite extends QueryTest with SharedSQLContext with SQLTestUtils with Te
checkAnswer(spark.read.option("multiLine", true).schema(schema).csv(input), Row(null))
assert(spark.read.csv(input).collect().toSet == Set(Row()))
}

test("field names of inferred schema shouldn't compare to the first row") {
val input = Seq("1,2").toDS()
val df = spark.read.option("enforceSchema", false).csv(input)
checkAnswer(df, Row("1", "2"))
}
}