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[SPARK-19919][SQL] Defer throwing the exception for empty paths in CSV datasource into DataSource #17256

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[SPARK-19919][SQL] Defer throwing the exception for empty paths in CSV datasource into DataSource #17256

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9d91da1
Defer input path validation into DataSource in CSV datasource
HyukjinKwon Mar 11, 2017
04e620c
Fix test
HyukjinKwon Mar 12, 2017
87d3fc8
Swap names (infer and inferSchema)
HyukjinKwon Mar 13, 2017
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25 changes: 18 additions & 7 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVDataSource.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -54,10 +54,21 @@ abstract class CSVDataSource extends Serializable {
/**
* Infers the schema from `inputPaths` files.
*/
def infer(
final def inferSchema(
sparkSession: SparkSession,
inputPaths: Seq[FileStatus],
parsedOptions: CSVOptions): Option[StructType]
parsedOptions: CSVOptions): Option[StructType] = {
if (inputPaths.nonEmpty) {
Some(infer(sparkSession, inputPaths, parsedOptions))
} else {
None
}
}

protected def infer(
sparkSession: SparkSession,
inputPaths: Seq[FileStatus],
parsedOptions: CSVOptions): StructType

/**
* Generates a header from the given row which is null-safe and duplicate-safe.
Expand Down Expand Up @@ -131,10 +142,10 @@ object TextInputCSVDataSource extends CSVDataSource {
override def infer(
sparkSession: SparkSession,
inputPaths: Seq[FileStatus],
parsedOptions: CSVOptions): Option[StructType] = {
parsedOptions: CSVOptions): StructType = {
val csv = createBaseDataset(sparkSession, inputPaths, parsedOptions)
val maybeFirstLine = CSVUtils.filterCommentAndEmpty(csv, parsedOptions).take(1).headOption
Some(inferFromDataset(sparkSession, csv, maybeFirstLine, parsedOptions))
inferFromDataset(sparkSession, csv, maybeFirstLine, parsedOptions)
}

/**
Expand Down Expand Up @@ -202,7 +213,7 @@ object WholeFileCSVDataSource extends CSVDataSource {
override def infer(
sparkSession: SparkSession,
inputPaths: Seq[FileStatus],
parsedOptions: CSVOptions): Option[StructType] = {
parsedOptions: CSVOptions): StructType = {
val csv = createBaseRdd(sparkSession, inputPaths, parsedOptions)
csv.flatMap { lines =>
UnivocityParser.tokenizeStream(
Expand All @@ -221,10 +232,10 @@ object WholeFileCSVDataSource extends CSVDataSource {
parsedOptions.headerFlag,
new CsvParser(parsedOptions.asParserSettings))
}
Some(CSVInferSchema.infer(tokenRDD, header, parsedOptions))
CSVInferSchema.infer(tokenRDD, header, parsedOptions)
case None =>
// If the first row could not be read, just return the empty schema.
Some(StructType(Nil))
StructType(Nil)
}
}

Expand Down
4 changes: 1 addition & 3 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/CSVFileFormat.scala
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Expand Up @@ -51,12 +51,10 @@ class CSVFileFormat extends TextBasedFileFormat with DataSourceRegister {
sparkSession: SparkSession,
options: Map[String, String],
files: Seq[FileStatus]): Option[StructType] = {
require(files.nonEmpty, "Cannot infer schema from an empty set of files")

val parsedOptions =
new CSVOptions(options, sparkSession.sessionState.conf.sessionLocalTimeZone)

CSVDataSource(parsedOptions).infer(sparkSession, files, parsedOptions)
CSVDataSource(parsedOptions).inferSchema(sparkSession, files, parsedOptions)
}

override def prepareWrite(
Expand Down
6 changes: 4 additions & 2 deletions sql/core/src/test/scala/org/apache/spark/sql/test/DataFrameReaderWriterSuite.scala
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Expand Up @@ -370,9 +370,11 @@ class DataFrameReaderWriterSuite extends QueryTest with SharedSQLContext with Be
val schema = df.schema

// Reader, without user specified schema
intercept[IllegalArgumentException] {
val message = intercept[AnalysisException] {
testRead(spark.read.csv(), Seq.empty, schema)
}
}.getMessage
assert(message.contains("Unable to infer schema for CSV. It must be specified manually."))

testRead(spark.read.csv(dir), data, schema)
testRead(spark.read.csv(dir, dir), data ++ data, schema)
testRead(spark.read.csv(Seq(dir, dir): _*), data ++ data, schema)
Expand Down