Revert "[SPARK-26248][SQL] Infer date type from CSV"

This reverts commit 5217f7b.

Author: HyukjinKwon

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/csv/CSVInferSchema.scala

@@ -22,20 +22,16 @@ import scala.util.control.Exception.allCatch
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.analysis.TypeCoercion
 import org.apache.spark.sql.catalyst.expressions.ExprUtils
-import org.apache.spark.sql.catalyst.util.{DateFormatter, TimestampFormatter}
+import org.apache.spark.sql.catalyst.util.TimestampFormatter
 import org.apache.spark.sql.types._
 
 class CSVInferSchema(val options: CSVOptions) extends Serializable {
 
   @transient
-  private lazy val timestampFormatter = TimestampFormatter(
+  private lazy val timestampParser = TimestampFormatter(
     options.timestampFormat,
     options.timeZone,
     options.locale)
-  @transient
-  private lazy val dateFormatter = DateFormatter(
-    options.dateFormat,
-    options.locale)
 
   private val decimalParser = {
     ExprUtils.getDecimalParser(options.locale)
@@ -108,7 +104,6 @@ class CSVInferSchema(val options: CSVOptions) extends Serializable {
           compatibleType(typeSoFar, tryParseDecimal(field)).getOrElse(StringType)
         case DoubleType => tryParseDouble(field)
         case TimestampType => tryParseTimestamp(field)
-        case DateType => tryParseDate(field)
         case BooleanType => tryParseBoolean(field)
         case StringType => StringType
         case other: DataType =>
@@ -164,16 +159,9 @@ class CSVInferSchema(val options: CSVOptions) extends Serializable {
   }
 
   private def tryParseTimestamp(field: String): DataType = {
-    if ((allCatch opt timestampFormatter.parse(field)).isDefined) {
+    // This case infers a custom `dataFormat` is set.
+    if ((allCatch opt timestampParser.parse(field)).isDefined) {
       TimestampType
-    } else {
-      tryParseDate(field)
-    }
-  }
-
-  private def tryParseDate(field: String): DataType = {
-    if ((allCatch opt dateFormatter.parse(field)).isDefined) {
-      DateType
     } else {
       tryParseBoolean(field)
     }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/csv/CSVInferSchemaSuite.scala

@@ -187,22 +187,4 @@ class CSVInferSchemaSuite extends SparkFunSuite with SQLHelper {
 
     Seq("en-US", "ko-KR", "ru-RU", "de-DE").foreach(checkDecimalInfer(_, DecimalType(7, 0)))
   }
-
-  test("inferring date type") {
-    var options = new CSVOptions(Map("dateFormat" -> "yyyy/MM/dd"), false, "GMT")
-    var inferSchema = new CSVInferSchema(options)
-    assert(inferSchema.inferField(NullType, "2018/12/02") == DateType)
-
-    options = new CSVOptions(Map("dateFormat" -> "MMM yyyy"), false, "GMT")
-    inferSchema = new CSVInferSchema(options)
-    assert(inferSchema.inferField(NullType, "Dec 2018") == DateType)
-
-    options = new CSVOptions(
-      Map("dateFormat" -> "yyyy-MM-dd", "timestampFormat" -> "yyyy-MM-dd'T'HH:mm:ss"),
-      columnPruning = false,
-      defaultTimeZoneId = "GMT")
-    inferSchema = new CSVInferSchema(options)
-    assert(inferSchema.inferField(NullType, "2018-12-03T11:00:00") == TimestampType)
-    assert(inferSchema.inferField(NullType, "2018-12-03") == DateType)
-  }
 }