alamb commented on code in PR #11066:
URL: https://github.com/apache/datafusion/pull/11066#discussion_r1650081511
##########
datafusion/optimizer/src/propagate_empty_relation.rs:
##########
@@ -142,13 +146,19 @@ impl OptimizerRule for PropagateEmptyRelation {
schema: join.schema.clone(),
}),
)),
+ JoinType::LeftAnti if right_empty => {
Review Comment:
I double checked that an ANTI join (e.g. a `NOT IN`) is true when there are
no tuples (aka the right side is emprt)
```sql
postgres=# select * from foo;
x
-----
1
2
NaN
(3 rows)
postgres=# select * from bar;
y
---
(0 rows)
postgres=# select x NOT IN (SELECT y from bar) from foo;
?column?
----------
t
t
t
(3 rows)
postgres=# select x from foo where NOT EXISTS (SELECT y from bar);
x
-----
1
2
NaN
(3 rows)
```
Thus I think this is a valid rewrite
##########
datafusion/optimizer/src/propagate_empty_relation.rs:
##########
@@ -142,13 +146,19 @@ impl OptimizerRule for PropagateEmptyRelation {
schema: join.schema.clone(),
}),
)),
+ JoinType::LeftAnti if right_empty => {
Review Comment:
I double checked that an ANTI join (e.g. a `NOT IN`) is true when there are
no tuples (aka the right side is emprt)
```sql
postgres=# select * from foo;
x
-----
1
2
NaN
(3 rows)
postgres=# select * from bar;
y
---
(0 rows)
postgres=# select x NOT IN (SELECT y from bar) from foo;
?column?
----------
t
t
t
(3 rows)
postgres=# select x from foo where NOT EXISTS (SELECT y from bar);
x
-----
1
2
NaN
(3 rows)
```
Thus I think this is a valid rewrite
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