jackwener commented on code in PR #8271:
URL: https://github.com/apache/arrow-datafusion/pull/8271#discussion_r1473855859
##########
datafusion/optimizer/src/decorrelate_predicate_subquery.rs:
##########
@@ -249,6 +249,38 @@ fn build_join(
.map(Option::Some)
})?;
+ // build a predicate for comparing the left and right expressions of a
given pair of outer/subquery rows
+ // from an IN or NOT IN predicate
+ let build_in_predicate = |left: Box<Expr>, right: Box<Expr>| ->
Result<Expr> {
+ let right_col = create_col_from_scalar_expr(right.deref(),
subquery_alias)?;
+ let eq_predicate =
+ Expr::eq(left.deref().clone(), Expr::Column(right_col.clone()));
+ if !query_info.negated {
+ // early exit if this is an IN predicate
+ return Ok(eq_predicate);
+ }
+
+ match left.nullable(outer_query.schema())? {
+ true => {
+ // left expression is nullable; we know the predicate must
take the form `left = right IS NOT FALSE`
+ return Ok(eq_predicate.is_not_false());
+ }
+ false => {}
+ }
+ let subquery_col = query_info
+ .query
+ .subquery
+ .schema()
+ .field_with_unqualified_name(right_col.name.as_str())?;
+
+ match subquery_col.is_nullable() {
+ // add "IS NOT FALSE" to a NOT IN equality predicate whose
subquery expression is nullable
+ // so that an unknown result is treated as a (possible) match
+ true => Ok(eq_predicate.is_not_false()),
+ false => Ok(eq_predicate),
+ }
+ };
+
Review Comment:
I suggest use these code to get a flag `null_equal_null`.
##########
datafusion/optimizer/src/decorrelate_predicate_subquery.rs:
##########
@@ -282,7 +312,7 @@ fn build_join(
true => JoinType::LeftAnti,
false => JoinType::LeftSemi,
};
- let new_plan = LogicalPlanBuilder::from(left.clone())
+ let new_plan = LogicalPlanBuilder::from(outer_query.clone())
.join_on(sub_query_alias, join_type, Some(join_filter))?
Review Comment:
```suggestion
.join_detailed(
sub_query_alias,
join_type,
(Vec::<Column>::new(), Vec::<Column>::new()),
Some(join_filter),
null_equal_null,
)```
##########
datafusion/optimizer/src/decorrelate_predicate_subquery.rs:
##########
@@ -282,7 +312,7 @@ fn build_join(
true => JoinType::LeftAnti,
false => JoinType::LeftSemi,
};
- let new_plan = LogicalPlanBuilder::from(left.clone())
+ let new_plan = LogicalPlanBuilder::from(outer_query.clone())
.join_on(sub_query_alias, join_type, Some(join_filter))?
Review Comment:
After we get `null_equal_null `, we fill it here.
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