[SPARK-26263][SQL] Validate partition values with user provided schema

## What changes were proposed in this pull request?

Currently if user provides data schema, partition column values are converted as per it. But if the conversion failed, e.g. converting string to int, the column value is null.

This PR proposes to throw exception in such case, instead of converting into null value silently:
1. These null partition column values doesn't make sense to users in most cases. It is better to show the conversion failure, and then users can adjust the schema or ETL jobs to fix it.
2. There are always exceptions on such conversion failure for non-partition data columns. Partition columns should have the same behavior.

We can reproduce the case above as following:
```
/tmp/testDir
├── p=bar
└── p=foo
```
If we run:
```
val schema = StructType(Seq(StructField("p", IntegerType, false)))
spark.read.schema(schema).csv("/tmp/testDir/").show()
```
We will get:
```
+----+
|   p|
+----+
|null|
|null|
+----+
```

## How was this patch tested?

Unit test

Closes apache#23215 from gengliangwang/SPARK-26263.

Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

Author: gengliangwang

docs/sql-migration-guide-upgrade.md

@@ -29,6 +29,8 @@ displayTitle: Spark SQL Upgrading Guide
 
   - In Spark version 2.4 and earlier, users can create a map with duplicated keys via built-in functions like `CreateMap`, `StringToMap`, etc. The behavior of map with duplicated keys is undefined, e.g. map look up respects the duplicated key appears first, `Dataset.collect` only keeps the duplicated key appears last, `MapKeys` returns duplicated keys, etc. Since Spark 3.0, these built-in functions will remove duplicated map keys with last wins policy. Users may still read map values with duplicated keys from data sources which do not enforce it (e.g. Parquet), the behavior will be udefined.
 
+  - In Spark version 2.4 and earlier, partition column value is converted as null if it can't be casted to corresponding user provided schema. Since 3.0, partition column value is validated with user provided schema. An exception is thrown if the validation fails. You can disable such validation by setting `spark.sql.sources.validatePartitionColumns` to `false`.
+
   - In Spark version 2.4 and earlier, the `SET` command works without any warnings even if the specified key is for `SparkConf` entries and it has no effect because the command does not update `SparkConf`, but the behavior might confuse users. Since 3.0, the command fails if a `SparkConf` key is used. You can disable such a check by setting `spark.sql.legacy.execution.setCommandRejectsSparkConfs` to `false`.
 
   - Spark applications which are built with Spark version 2.4 and prior, and call methods of `UserDefinedFunction`, need to be re-compiled with Spark 3.0, as they are not binary compatible with Spark 3.0.

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -1396,6 +1396,16 @@ object SQLConf {
     .booleanConf
     .createWithDefault(false)
 
+  val VALIDATE_PARTITION_COLUMNS =
+    buildConf("spark.sql.sources.validatePartitionColumns")
+      .internal()
+      .doc("When this option is set to true, partition column values will be validated with " +
+        "user-specified schema. If the validation fails, a runtime exception is thrown." +
+        "When this option is set to false, the partition column value will be converted to null " +
+        "if it can not be casted to corresponding user-specified schema.")
+      .booleanConf
+      .createWithDefault(true)
+
   val CONTINUOUS_STREAMING_EXECUTOR_QUEUE_SIZE =
     buildConf("spark.sql.streaming.continuous.executorQueueSize")
     .internal()
@@ -2014,6 +2024,8 @@ class SQLConf extends Serializable with Logging {
   def allowCreatingManagedTableUsingNonemptyLocation: Boolean =
     getConf(ALLOW_CREATING_MANAGED_TABLE_USING_NONEMPTY_LOCATION)
 
+  def validatePartitionColumns: Boolean = getConf(VALIDATE_PARTITION_COLUMNS)
+
   def partitionOverwriteMode: PartitionOverwriteMode.Value =
     PartitionOverwriteMode.withName(getConf(PARTITION_OVERWRITE_MODE))
 

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningAwareFileIndex.scala

@@ -127,13 +127,13 @@ abstract class PartitioningAwareFileIndex(
     val timeZoneId = caseInsensitiveOptions.get(DateTimeUtils.TIMEZONE_OPTION)
       .getOrElse(sparkSession.sessionState.conf.sessionLocalTimeZone)
 
-    val caseSensitive = sparkSession.sqlContext.conf.caseSensitiveAnalysis
     PartitioningUtils.parsePartitions(
       leafDirs,
       typeInference = sparkSession.sessionState.conf.partitionColumnTypeInferenceEnabled,
       basePaths = basePaths,
       userSpecifiedSchema = userSpecifiedSchema,
-      caseSensitive = caseSensitive,
+      caseSensitive = sparkSession.sqlContext.conf.caseSensitiveAnalysis,
+      validatePartitionColumns = sparkSession.sqlContext.conf.validatePartitionColumns,
       timeZoneId = timeZoneId)
   }
 

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningUtils.scala

@@ -26,12 +26,13 @@ import scala.util.Try
 
 import org.apache.hadoop.fs.Path
 
-import org.apache.spark.sql.AnalysisException
+import org.apache.spark.sql.{AnalysisException, SparkSession}
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.{Resolver, TypeCoercion}
 import org.apache.spark.sql.catalyst.catalog.CatalogTypes.TablePartitionSpec
 import org.apache.spark.sql.catalyst.expressions.{Attribute, Cast, Literal}
 import org.apache.spark.sql.catalyst.util.{CaseInsensitiveMap, DateTimeUtils}
+import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types._
 import org.apache.spark.sql.util.SchemaUtils
 
@@ -96,9 +97,10 @@ object PartitioningUtils {
       basePaths: Set[Path],
       userSpecifiedSchema: Option[StructType],
       caseSensitive: Boolean,
+      validatePartitionColumns: Boolean,
       timeZoneId: String): PartitionSpec = {
-    parsePartitions(paths, typeInference, basePaths, userSpecifiedSchema,
-      caseSensitive, DateTimeUtils.getTimeZone(timeZoneId))
+    parsePartitions(paths, typeInference, basePaths, userSpecifiedSchema, caseSensitive,
+      validatePartitionColumns, DateTimeUtils.getTimeZone(timeZoneId))
   }
 
   private[datasources] def parsePartitions(
@@ -107,6 +109,7 @@ object PartitioningUtils {
       basePaths: Set[Path],
       userSpecifiedSchema: Option[StructType],
       caseSensitive: Boolean,
+      validatePartitionColumns: Boolean,
       timeZone: TimeZone): PartitionSpec = {
     val userSpecifiedDataTypes = if (userSpecifiedSchema.isDefined) {
       val nameToDataType = userSpecifiedSchema.get.fields.map(f => f.name -> f.dataType).toMap
@@ -121,7 +124,8 @@ object PartitioningUtils {
 
     // First, we need to parse every partition's path and see if we can find partition values.
     val (partitionValues, optDiscoveredBasePaths) = paths.map { path =>
-      parsePartition(path, typeInference, basePaths, userSpecifiedDataTypes, timeZone)
+      parsePartition(path, typeInference, basePaths, userSpecifiedDataTypes,
+        validatePartitionColumns, timeZone)
     }.unzip
 
     // We create pairs of (path -> path's partition value) here
@@ -203,6 +207,7 @@ object PartitioningUtils {
       typeInference: Boolean,
       basePaths: Set[Path],
       userSpecifiedDataTypes: Map[String, DataType],
+      validatePartitionColumns: Boolean,
       timeZone: TimeZone): (Option[PartitionValues], Option[Path]) = {
     val columns = ArrayBuffer.empty[(String, Literal)]
     // Old Hadoop versions don't have `Path.isRoot`
@@ -224,7 +229,8 @@ object PartitioningUtils {
         // Let's say currentPath is a path of "/table/a=1/", currentPath.getName will give us a=1.
         // Once we get the string, we try to parse it and find the partition column and value.
         val maybeColumn =
-          parsePartitionColumn(currentPath.getName, typeInference, userSpecifiedDataTypes, timeZone)
+          parsePartitionColumn(currentPath.getName, typeInference, userSpecifiedDataTypes,
+            validatePartitionColumns, timeZone)
         maybeColumn.foreach(columns += _)
 
         // Now, we determine if we should stop.
@@ -258,6 +264,7 @@ object PartitioningUtils {
       columnSpec: String,
       typeInference: Boolean,
       userSpecifiedDataTypes: Map[String, DataType],
+      validatePartitionColumns: Boolean,
       timeZone: TimeZone): Option[(String, Literal)] = {
     val equalSignIndex = columnSpec.indexOf('=')
     if (equalSignIndex == -1) {
@@ -272,10 +279,15 @@ object PartitioningUtils {
       val literal = if (userSpecifiedDataTypes.contains(columnName)) {
         // SPARK-26188: if user provides corresponding column schema, get the column value without
         //              inference, and then cast it as user specified data type.
-        val columnValue = inferPartitionColumnValue(rawColumnValue, false, timeZone)
-        val castedValue =
-          Cast(columnValue, userSpecifiedDataTypes(columnName), Option(timeZone.getID)).eval()
-        Literal.create(castedValue, userSpecifiedDataTypes(columnName))
+        val dataType = userSpecifiedDataTypes(columnName)
+        val columnValueLiteral = inferPartitionColumnValue(rawColumnValue, false, timeZone)
+        val columnValue = columnValueLiteral.eval()
+        val castedValue = Cast(columnValueLiteral, dataType, Option(timeZone.getID)).eval()
+        if (validatePartitionColumns && columnValue != null && castedValue == null) {
+          throw new RuntimeException(s"Failed to cast value `$columnValue` to `$dataType` " +
+            s"for partition column `$columnName`")
+        }
+        Literal.create(castedValue, dataType)
       } else {
         inferPartitionColumnValue(rawColumnValue, typeInference, timeZone)
       }

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileIndexSuite.scala

@@ -30,7 +30,7 @@ import org.apache.spark.sql.catalyst.util._
 import org.apache.spark.sql.functions.col
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.test.SharedSQLContext
-import org.apache.spark.sql.types.{StringType, StructField, StructType}
+import org.apache.spark.sql.types.{IntegerType, StringType, StructField, StructType}
 import org.apache.spark.util.{KnownSizeEstimation, SizeEstimator}
 
 class FileIndexSuite extends SharedSQLContext {
@@ -95,6 +95,31 @@ class FileIndexSuite extends SharedSQLContext {
     }
   }
 
+  test("SPARK-26263: Throw exception when partition value can't be casted to user-specified type") {
+    withTempDir { dir =>
+      val partitionDirectory = new File(dir, "a=foo")
+      partitionDirectory.mkdir()
+      val file = new File(partitionDirectory, "text.txt")
+      stringToFile(file, "text")
+      val path = new Path(dir.getCanonicalPath)
+      val schema = StructType(Seq(StructField("a", IntegerType, false)))
+      withSQLConf(SQLConf.VALIDATE_PARTITION_COLUMNS.key -> "true") {
+        val fileIndex = new InMemoryFileIndex(spark, Seq(path), Map.empty, Some(schema))
+        val msg = intercept[RuntimeException] {
+          fileIndex.partitionSpec()
+        }.getMessage
+        assert(msg == "Failed to cast value `foo` to `IntegerType` for partition column `a`")
+      }
+
+      withSQLConf(SQLConf.VALIDATE_PARTITION_COLUMNS.key -> "false") {
+        val fileIndex = new InMemoryFileIndex(spark, Seq(path), Map.empty, Some(schema))
+        val partitionValues = fileIndex.partitionSpec().partitions.map(_.values)
+        assert(partitionValues.length == 1 && partitionValues(0).numFields == 1 &&
+          partitionValues(0).isNullAt(0))
+      }
+    }
+  }
+
   test("InMemoryFileIndex: input paths are converted to qualified paths") {
     withTempDir { dir =>
       val file = new File(dir, "text.txt")

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetPartitionDiscoverySuite.scala

@@ -101,7 +101,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       "hdfs://host:9000/path/a=10.5/b=hello")
 
     var exception = intercept[AssertionError] {
-      parsePartitions(paths.map(new Path(_)), true, Set.empty[Path], None, true, timeZoneId)
+      parsePartitions(paths.map(new Path(_)), true, Set.empty[Path], None, true, true, timeZoneId)
     }
     assert(exception.getMessage().contains("Conflicting directory structures detected"))
 
@@ -117,6 +117,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       Set(new Path("hdfs://host:9000/path/")),
       None,
       true,
+      true,
       timeZoneId)
 
     // Valid
@@ -132,6 +133,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       Set(new Path("hdfs://host:9000/path/something=true/table")),
       None,
       true,
+      true,
       timeZoneId)
 
     // Valid
@@ -147,6 +149,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       Set(new Path("hdfs://host:9000/path/table=true")),
       None,
       true,
+      true,
       timeZoneId)
 
     // Invalid
@@ -162,6 +165,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
         Set(new Path("hdfs://host:9000/path/")),
         None,
         true,
+        true,
         timeZoneId)
     }
     assert(exception.getMessage().contains("Conflicting directory structures detected"))
@@ -184,20 +188,22 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
         Set(new Path("hdfs://host:9000/tmp/tables/")),
         None,
         true,
+        true,
         timeZoneId)
     }
     assert(exception.getMessage().contains("Conflicting directory structures detected"))
   }
 
   test("parse partition") {
     def check(path: String, expected: Option[PartitionValues]): Unit = {
-      val actual = parsePartition(new Path(path), true, Set.empty[Path], Map.empty, timeZone)._1
+      val actual = parsePartition(new Path(path), true, Set.empty[Path],
+        Map.empty, true, timeZone)._1
       assert(expected === actual)
     }
 
     def checkThrows[T <: Throwable: Manifest](path: String, expected: String): Unit = {
       val message = intercept[T] {
-        parsePartition(new Path(path), true, Set.empty[Path], Map.empty, timeZone)
+        parsePartition(new Path(path), true, Set.empty[Path], Map.empty, true, timeZone)
       }.getMessage
 
       assert(message.contains(expected))
@@ -242,6 +248,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       typeInference = true,
       basePaths = Set(new Path("file://path/a=10")),
       Map.empty,
+      true,
       timeZone = timeZone)._1
 
     assert(partitionSpec1.isEmpty)
@@ -252,6 +259,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
       typeInference = true,
       basePaths = Set(new Path("file://path")),
       Map.empty,
+      true,
       timeZone = timeZone)._1
 
     assert(partitionSpec2 ==
@@ -272,6 +280,7 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
           rootPaths,
           None,
           true,
+          true,
           timeZoneId)
       assert(actualSpec.partitionColumns === spec.partitionColumns)
       assert(actualSpec.partitions.length === spec.partitions.length)
@@ -384,7 +393,8 @@ class ParquetPartitionDiscoverySuite extends QueryTest with ParquetTest with Sha
   test("parse partitions with type inference disabled") {
     def check(paths: Seq[String], spec: PartitionSpec): Unit = {
       val actualSpec =
-        parsePartitions(paths.map(new Path(_)), false, Set.empty[Path], None, true, timeZoneId)
+        parsePartitions(paths.map(new Path(_)), false, Set.empty[Path], None,
+          true, true, timeZoneId)
       assert(actualSpec === spec)
     }