Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/2543#discussion_r18316116
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -118,6 +120,19 @@ class Analyzer(catalog: Catalog, registry:
FunctionRegistry, caseSensitive: Bool
}
/**
+ * Make [[GetField]] case insensitive by passing a findField function
+ */
+ object ResolveGetField extends Rule[LogicalPlan] {
+ def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+ case q: LogicalPlan =>
+ q transformExpressions {
+ case GetField(child, fieldName, null) =>
+ GetField(child, fieldName, f => resolver(f.name, fieldName))
+ }
--- End diff --
What about something like:
```scala
q transformExpressions {
case g @ GetField(child, fieldName) if child.resolved && ! g.resolved =>
val options = g.structType.fields.filter(f => resolver(f.name,
fieldName))
options match {
case Seq(oneMatch) => GetField(child, oneMatch)
case Seq() => g // No match: leave unresolved
case multipleMatches =>
sys.error(s"Ambiguious reference to $fieldName matches
${multipleMatches.mkString(",")}")
}
}
```
That way all logic related to resolution happens here in the analyzer and
GetField can remain unchanged.
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