bersprockets commented on a change in pull request #29737:
URL: https://github.com/apache/spark/pull/29737#discussion_r490289663
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala
##########
@@ -142,13 +142,17 @@ 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"))) {
- // This is a ORC file written by Hive, no field names in the physical
schema, assume the
- // physical schema maps to the data scheme by index.
+ if (forcePositionalEvolution ||
orcFieldNames.forall(_.startsWith("_col"))) {
+ // This is either an ORC file written by an old versions of Hive and
there are no field
+ // names in the physical schema, or a file written by a newer versions
of Hive where
+ // `orc.force.positional.evolution=true` and columns were renamed so
the physical schema
Review comment:
Super tiny nit (feel free to ignore if it doesn't make sense to you). I
suggest:
`orc.force.positional.evolution=true` (possibly because columns were renamed
so the physical schema doesn't match the data schema).
Your current version of the comment implies
orc.force.positional.evolution=true will happen when the columns are renamed.
But you can set orc.force.positional.evolution=true anytime, and you can rename
the columns and neglect to set orc.force.positional.evolution, correct?
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala
##########
@@ -142,13 +142,17 @@ 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"))) {
- // This is a ORC file written by Hive, no field names in the physical
schema, assume the
- // physical schema maps to the data scheme by index.
+ if (forcePositionalEvolution ||
orcFieldNames.forall(_.startsWith("_col"))) {
+ // This is either an ORC file written by an old versions of Hive and
there are no field
Review comment:
Super tiny nit: "written by an old versions of Hive" should be
written by an old version of Hive
or
written by old versions of Hive
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