alamb commented on code in PR #10356:
URL: https://github.com/apache/datafusion/pull/10356#discussion_r1589027335
##########
datafusion/optimizer/src/analyzer/type_coercion.rs:
##########
@@ -99,25 +102,75 @@ fn analyze_internal(
// select t2.c2 from t1 where t1.c1 in (select t2.c1 from t2 where
t2.c2=t1.c3)
schema.merge(external_schema);
- let mut expr_rewrite = TypeCoercionRewriter { schema: &schema };
-
- let new_expr = plan
- .expressions()
- .into_iter()
- .map(|expr| {
- // ensure aggregate names don't change:
- // https://github.com/apache/datafusion/issues/3555
- rewrite_preserving_name(expr, &mut expr_rewrite)
- })
- .collect::<Result<Vec<_>>>()?;
-
- plan.with_new_exprs(new_expr, new_inputs)
+ let mut expr_rewrite = TypeCoercionRewriter::new(&schema);
+
+ let name_preserver = NamePreserver::new(&plan);
+ // apply coercion rewrite all expressions in the plan indivdually
+ plan.map_expressions(|expr| {
+ let original_name = name_preserver.save(&expr)?;
+ expr.rewrite(&mut expr_rewrite)?
+ .map_data(|expr| original_name.restore(expr))
+ })?
+ // coerce join expressions specially
+ .map_data(|plan| expr_rewrite.coerce_joins(plan))?
+ // recompute the schema after the expressions have been rewritten as the
types may have changed
+ .map_data(|plan| plan.recompute_schema())
Review Comment:
You are correct (of course!) thank you for pointing it out. Now that
`analyze_internal` returns Transformed would work. However, there is still
code like this:
```rust
let new_plan =
analyze_internal(self.schema,
unwrap_arc(subquery.subquery))?.data;
Ok(Transformed::yes(Expr::Exists(Exists {
subquery: Subquery {
subquery: Arc::new(new_plan),
outer_ref_columns: subquery.outer_ref_columns,
},
negated,
})))
}
```
Which discards the transformed information (and in this case always returns
Transformed::true).
In order to keep the PRs small and easier to review I would like to not
change this PR (it is no worse than `main` in regards to recomputing schema)
and I will make a follow on PR to avoid recomputing schema when unecessary
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