Github user budde commented on a diff in the pull request:
https://github.com/apache/spark/pull/16944#discussion_r104271287
--- Diff:
sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala ---
@@ -217,6 +227,62 @@ private[hive] class HiveMetastoreCatalog(sparkSession:
SparkSession) extends Log
result.copy(expectedOutputAttributes = Some(relation.output))
}
+ private def inferIfNeeded(
+ relation: CatalogRelation,
+ options: Map[String, String],
+ fallbackSchema: StructType,
+ fileFormat: FileFormat,
+ fileIndexOpt: Option[FileIndex] = None): (StructType, CatalogTable)
= {
+ val inferenceMode =
sparkSession.sessionState.conf.caseSensitiveInferenceMode
+ val shouldInfer = (inferenceMode != NEVER_INFER) &&
!relation.tableMeta.schemaPreservesCase
+ val tableName = relation.tableMeta.identifier.table
+ if (shouldInfer) {
+ logInfo(s"Inferring case-sensitive schema for table $tableName
(inference mode: " +
+ s"$inferenceMode)")
+ val fileIndex = fileIndexOpt.getOrElse {
+ val rootPath = new Path(new URI(relation.tableMeta.location))
+ new InMemoryFileIndex(sparkSession, Seq(rootPath), options, None)
+ }
+
+ val inferredSchema = {
+ val schema = fileFormat.inferSchema(
+ sparkSession,
+ options,
+ fileIndex.listFiles(Nil).flatMap(_.files))
+ fileFormat match {
+ case _: ParquetFileFormat =>
+
schema.map(ParquetFileFormat.mergeMetastoreParquetSchema(relation.tableMeta.schema,
_))
+ case _ =>
+ schema
+ }
+ }
+
+ inferredSchema match {
+ case Some(schema) =>
+ if (inferenceMode == INFER_AND_SAVE) {
+ updateCatalogSchema(relation.tableMeta.identifier, schema)
--- End diff --
Thanks, I understand the issue with this now. I'll add code to merge the
partition columns back in regardless of the file format. If we want to merge
any nullable fields from the metastore schema that are missing from
```inferredSchema``` (see comment above) we probably want to do this explicitly
as well.
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