kumarUjjawal commented on code in PR #24808:
URL: https://github.com/apache/datafusion/pull/24808#discussion_r3891533233
##########
datafusion/sql/src/unparser/plan.rs:
##########
@@ -829,6 +847,61 @@ impl Unparser<'_> {
columns,
);
}
+
+ let qualified_projection = p.expr.iter().try_fold(false,
|found, expr| {
+ if found {
+ Ok(true)
+ } else {
+ expr.exists(|expr| {
+ Ok(matches!(expr, Expr::Column(column) if
column.relation.is_some()))
+ })
+ }
+ })?;
+ let mut input_names = HashSet::new();
+ let unique_input_names = p
+ .input
+ .schema()
+ .fields()
+ .iter()
+ .all(|field| input_names.insert(field.name()));
+ if let Some(input_alias) =
Self::derived_input_alias(p.input.as_ref())
+ && qualified_projection
+ && unique_input_names
+ && find_unnest_node_within_select(plan).is_none()
+ && !select.inside_subquery_alias()
+ {
+ // The input is about to enter a new SQL scope. Preserve
that
+ // boundary explicitly and make the outer expressions
resolve
+ // against the relation that will actually be visible
there.
+ let requires_alias =
self.dialect.requires_derived_table_alias();
+ let alias = requires_alias
+ .then(|| self.new_table_alias(input_alias.to_string(),
vec![]));
+ self.derive(p.input.as_ref(), relation, alias, false)?;
Review Comment:
The new scope rewrite changes only the `SELECT` items. An outer `Sort` is
rendered before this branch and keeps the old qualifier.
For example, `SELECT j1_id FROM (...) ORDER BY j1_id` can still emit `ORDER
BY ta.j1_id`. Only `derived_projection` is visible there.
The same problem applies to an outer filter rendered before this branch.
Please rebase all outer clauses and add an `ORDER BY` regression.
##########
datafusion/sql/src/unparser/ast.rs:
##########
@@ -195,6 +197,19 @@ impl SelectBuilder {
self.flatten_table_aliases.iter().any(|a| a == alias)
}
+ pub fn enter_subquery_alias(&mut self) {
Review Comment:
These methods are public because `ast` is a public module. Only the unparser
uses this scope state.
Please use `pub(super)` for these three methods.
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