ygf11 commented on code in PR #5593:
URL: https://github.com/apache/arrow-datafusion/pull/5593#discussion_r1139948465
##########
datafusion/sql/src/expr/subquery.rs:
##########
@@ -30,13 +30,15 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
input_schema: &DFSchema,
planner_context: &mut PlannerContext,
) -> Result<Expr> {
+ let old_outer_query_schema =
planner_context.outer_query_schema.clone();
+ planner_context.outer_query_schema = Some(input_schema.clone());
+ let sub_plan = self.query_to_plan(subquery, planner_context)?;
+ let outer_ref_columns = sub_plan.all_out_ref_exprs();
+ planner_context.outer_query_schema = old_outer_query_schema;
Review Comment:
Can we support the following subquery in the future?
```sql
# three level
# the innermost(`t3`) reference outermost(`t1`) column
SELECT *
FROM t1
WHERE EXISTS (
SELECT *
FROM t2
WHERE t1_id = t2_id
AND EXISTS (
SELECT *
FROM t3
WHERE t3_id > t1_id
)
);
```
I just think the optimizer rule you plan to
add(https://github.com/apache/arrow-datafusion/issues/5492) can also optimize
it.
##########
datafusion/expr/src/logical_plan/plan.rs:
##########
@@ -1919,14 +1947,11 @@ impl Join {
pub struct Subquery {
/// The subquery
pub subquery: Arc<LogicalPlan>,
+ /// The outer references used in the subquery
+ pub outer_ref_columns: Vec<Expr>,
Review Comment:
👍 This field can help to check if it is a correlated subquery.
##########
datafusion/expr/src/expr_fn.rs:
##########
@@ -267,15 +267,21 @@ pub fn approx_percentile_cont_with_weight(
/// Create an EXISTS subquery expression
pub fn exists(subquery: Arc<LogicalPlan>) -> Expr {
Expr::Exists {
- subquery: Subquery { subquery },
+ subquery: Subquery {
+ subquery,
+ outer_ref_columns: vec![],
+ },
Review Comment:
Maybe we can add `outer_ref_columns` as argument?
I find some tests depend it, and we can cover more test(I can help add this).
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