alamb commented on code in PR #5748:
URL: https://github.com/apache/arrow-datafusion/pull/5748#discussion_r1152231567
##########
datafusion/expr/src/logical_plan/builder.rs:
##########
@@ -1041,20 +1041,44 @@ pub fn build_join_schema(
right: &DFSchema,
join_type: &JoinType,
) -> Result<DFSchema> {
+ let right_fields = right.fields();
+ let left_fields = left.fields();
+
let fields: Vec<DFField> = match join_type {
- JoinType::Inner | JoinType::Left | JoinType::Full | JoinType::Right =>
{
- let right_fields = right.fields().iter();
- let left_fields = left.fields().iter();
+ JoinType::Inner | JoinType::Full | JoinType::Right => {
// left then right
- left_fields.chain(right_fields).cloned().collect()
+ left_fields
+ .iter()
+ .chain(right_fields.iter())
+ .cloned()
+ .collect()
+ }
+ JoinType::Left => {
+ // left then right, right set to nullable in case of not matched
scenario
+ let right_fields_nullable: Vec<DFField> = right_fields
+ .iter()
+ .map(|f| {
+ let field = f.field().clone().with_nullable(true);
+ if let Some(q) = f.qualifier() {
+ DFField::from_qualified(q, field)
+ } else {
+ DFField::from(field)
Review Comment:
Maybe we could add a `DFField::with_nullable` to make this more concise:
```
let field = f.clone().with_nullable(true);
```
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