Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/9055#discussion_r42586165
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
---
@@ -408,6 +552,25 @@ class Analyzer(
}
}
+ // Try to resolve the attributes from the given logical plan
+ def tryResolveAttributes(expr: Expression, q: LogicalPlan): Expression
= {
+ checkAnalysis(q)
+ val projection = Project(q.output, q)
+
+ logTrace(s"Attempting to resolve ${expr.simpleString}")
+ expr transformUp {
+ case u @ UnresolvedAlias(expr) => expr
+ case u @ UnresolvedAttribute(nameParts) =>
+ // Leave unchanged if resolution fails. Hopefully will be
resolved next round.
+ val result =
+ withPosition(u) { projection.resolveChildren(nameParts,
resolver).getOrElse(u) }
+ logDebug(s"Resolving $u to $result")
+ result
+ case UnresolvedExtractValue(child, fieldExpr) if child.resolved =>
+ ExtractValue(child, fieldExpr, resolver)
+ }
+ }
+
--- End diff --
This is the rule that I copied from the `ResolveReferences` with slight
changes, maybe we should leave it along `ResolveReferences`, otherwise people
probably forgot to update it once we need to update the logic of attributes
resolution.
And I was planning to move this code into the `LogicalPlan`, but need more
thinking how to make the code shared with the rule `ResolveReferences`, how
about leave it for the further improvement?
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