miland-db commented on code in PR #53508:
URL: https://github.com/apache/spark/pull/53508#discussion_r2635615237
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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala:
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@@ -695,19 +695,43 @@ object ViewSyncSchemaToMetaStore extends (LogicalPlan =>
Unit) {
(field.dataType != planField.dataType ||
field.nullable != planField.nullable ||
(viewSchemaMode == SchemaEvolution && (
- field.getComment() != planField.getComment() ||
- field.name != planField.name)))
+ field.name != planField.name ||
+ // Only trigger redo on comment changes if preserve flag is
disabled.
+
(!session.sessionState.conf.viewSchemaEvolutionPreserveUserComments &&
+ field.getComment() != planField.getComment()))))
}
+ lazy val viewFieldsByName = viewFields.map(f => f.name -> f).toMap
+
if (redo) {
val newSchema = if (viewSchemaMode == SchemaTypeEvolution) {
val newFields = viewQuery.schema.map {
case StructField(name, dataType, nullable, _) =>
StructField(name, dataType, nullable,
- viewFields.find(_.name == name).get.metadata)
+ viewFieldsByName(name).metadata)
+ }
+ StructType(newFields)
+ } else if
(session.sessionState.conf.viewSchemaEvolutionPreserveUserComments) {
+ // Adopt types/nullable/names from query, but preserve view
comments.
+ val newFields = viewQuery.schema.map { planField =>
+ val newMetadata = viewFieldsByName.get(planField.name) match {
+ case Some(viewField) =>
+ // Use table metadata but override with view comment
+ val builder = new
MetadataBuilder().withMetadata(planField.metadata)
+ viewField.getComment() match {
+ case Some(comment) => builder.putString("comment", comment)
+ case None => builder.remove("comment")
Review Comment:
The idea is to always preserve view state:
- If view has comment then use it
- If view has no comment then keep it empty (even if table has one). It is
possible that user deleted the comment, and we don't want to override that user
decision.
@srielau please confirm
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