AngersZhuuuu commented on a change in pull request #28490:
URL: https://github.com/apache/spark/pull/28490#discussion_r480974176
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
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@@ -1326,24 +1326,49 @@ class Analyzer(
* Note : In this routine, the unresolved attributes are resolved from the
input plan's
* children attributes.
*/
- private def resolveExpressionTopDown(e: Expression, q: LogicalPlan):
Expression = {
- if (e.resolved) return e
- e match {
- case f: LambdaFunction if !f.bound => f
- case u @ UnresolvedAttribute(nameParts) =>
- // Leave unchanged if resolution fails. Hopefully will be resolved
next round.
- val result =
- withPosition(u) {
- q.resolveChildren(nameParts, resolver)
- .orElse(resolveLiteralFunction(nameParts, u, q))
- .getOrElse(u)
+ private def resolveExpressionTopDown(
+ e: Expression,
+ q: LogicalPlan,
+ trimAlias: Boolean = false): Expression = {
+
+ // Explain for param trimAlias and isTopLevel:
Review comment:
> The previous parameter doc of `resolveExpressionTopDown` is good. Why
we turn it to comment here?
Since we don't have isTopLevel param in `resolveExpressionTopDow`. emm how
about
```
* @param e the expression need to be resolved.
* @param q the LogicalPlan whose children are used to resolve
expression's attribute.
* @param trimAlias whether need to trim alias of Struct field. When
true, we will trim
* Struct field alias. When isTopLevel = true, we won't
trim top-level
* Struct field alias.
* @return resolved Expression.
*/
private def resolveExpressionTopDown(
e: Expression,
q: LogicalPlan,
trimAlias: Boolean = false): Expression = {
// Explain for param trimAlias and isTopLevel:
// 1. trimAlias = false:
// We won't trim Struct Field alias.
// 2. trimAlias = true && isTopLevel = false:
// We will trim all Struct field alias.
// 3. trimAlias = true && isTopLevel = true
// Trim unnecessary alias of `GetStructField`. Note that, we cannot
trim the alias of
// top-level `GetStructField`, as we should resolve
`UnresolvedAttribute` to a named
// expression. The caller side can trim the alias of top-level
`GetStructField` if needed.
def innerResolve(
e: Expression,
isTopLevel: Boolean): Expression = {
if (e.resolved) return e
```
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