cloud-fan commented on a change in pull request #27350: [SPARK-30615][SQL]
Introduce Analyzer rule for V2 AlterTable column change resolution
URL: https://github.com/apache/spark/pull/27350#discussion_r373350285
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
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@@ -3002,6 +3004,160 @@ class Analyzer(
}
}
}
+
+ /** Rule to mostly resolve, normalize and rewrite column names based on case
sensitivity. */
+ object ResolveAlterTableChanges extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = plan.resolveOperatorsUp {
+ case a @ AlterTable(_, _, t: NamedRelation, changes) if t.resolved =>
+ val schema = t.schema
+ val normalizedChanges = changes.flatMap {
+ case add: AddColumn =>
+ val parent = add.fieldNames().init
+ if (parent.nonEmpty) {
+ // Adding a nested field, need to normalize the parent column
and position
+ val target = schema.findNestedField(parent, includeCollections =
true, conf.resolver)
+ if (target.isEmpty) {
+ // Leave unresolved. Throws error in CheckAnalysis
+ Some(add)
+ } else {
+ val (normalizedName, sf) = target.get
+ sf.dataType match {
+ case struct: StructType =>
+ val pos = findColumnPosition(add.position(),
parent.quoted, struct)
+ Some(TableChange.addColumn(
+ (normalizedName ++ Seq(sf.name,
add.fieldNames().last)).toArray,
+ add.dataType(),
+ add.isNullable,
+ add.comment,
+ pos))
+
+ case other =>
+ Some(add)
+ }
+ }
+ } else {
+ // Adding to the root. Just need to normalize position
+ val pos = findColumnPosition(add.position(), "root", schema)
+ Some(TableChange.addColumn(
+ add.fieldNames(),
+ add.dataType(),
+ add.isNullable,
+ add.comment,
+ pos))
+ }
+
+ case typeChange: UpdateColumnType =>
+ // Hive style syntax provides the column type, even if it may not
have changed
+ val fieldOpt = schema.findNestedField(
+ typeChange.fieldNames(), includeCollections = true,
conf.resolver)
+
+ if (fieldOpt.isEmpty) {
+ // We couldn't resolve the field. Leave it to CheckAnalysis
+ Some(typeChange)
+ } else {
+ val (fieldNames, field) = fieldOpt.get
+ if (field.dataType == typeChange.newDataType()) {
+ // The user didn't want the field to change, so remove this
change
Review comment:
I think we can remove other column changes if they are noop, e.g.
`UpdateColumnNullability` without changing nullability. We can address it in a
followup.
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