[GitHub] [spark] peter-toth commented on a change in pull request #29737: [SPARK-32864][SQL] Support ORC forced positional evolution

[GitBox <gi...@apache.org>]

peter-toth commented on a change in pull request #29737:
URL: https://github.com/apache/spark/pull/29737#discussion_r489386143



##########
File path: sql/hive/src/test/scala/org/apache/spark/sql/hive/orc/HiveOrcQuerySuite.scala
##########
@@ -316,4 +317,24 @@ class HiveOrcQuerySuite extends OrcQueryTest with TestHiveSingleton {
       }
     }
   }
+
+  test("SPARK-32864: Support ORC forced positional evolution") {
+    Seq("native", "hive").foreach { orcImpl =>
+      withSQLConf(SQLConf.ORC_IMPLEMENTATION.key -> orcImpl,
+        OrcConf.FORCE_POSITIONAL_EVOLUTION.getAttribute -> "true") {
+        withTempPath { f =>
+          val path = f.getCanonicalPath
+          Seq(1 -> 2).toDF("c1", "c2").write.orc(path)
+          checkAnswer(spark.read.orc(path), Row(1, 2))
+
+          withSQLConf(HiveUtils.CONVERT_METASTORE_ORC.key -> "true") { // default since 2.3.0
+            withTable("t") {
+              sql(s"CREATE EXTERNAL TABLE t(c3 INT, c4 INT) STORED AS ORC LOCATION '$path'")
+              checkAnswer(spark.table("t"), Row(1, 2))

Review comment:
       Thanks. I've extended the test with that case.

##########
File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala
##########
@@ -142,11 +142,12 @@ object OrcUtils extends Logging {
       reader: Reader,
       conf: Configuration): Option[(Array[Int], Boolean)] = {
     val orcFieldNames = reader.getSchema.getFieldNames.asScala
+    val forcePositionalEvolution = OrcConf.FORCE_POSITIONAL_EVOLUTION.getBoolean(conf)
     if (orcFieldNames.isEmpty) {
       // SPARK-8501: Some old empty ORC files always have an empty schema stored in their footer.
       None
     } else {
-      if (orcFieldNames.forall(_.startsWith("_col"))) {
+      if (forcePositionalEvolution || orcFieldNames.forall(_.startsWith("_col"))) {
         // This is a ORC file written by Hive, no field names in the physical schema, assume the

Review comment:
       Done.




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