alamb commented on code in PR #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342#discussion_r859066917
##########
datafusion/expr/src/expr_schema.rs:
##########
@@ -173,7 +177,13 @@ impl ExprSchemable for Expr {
| Expr::WindowFunction { .. }
| Expr::AggregateFunction { .. }
| Expr::AggregateUDF { .. } => Ok(true),
- Expr::IsNull(_) | Expr::IsNotNull(_) | Expr::Exists(_) =>
Ok(false),
+ Expr::IsNull(_)
+ | Expr::IsNotNull(_)
+ | Expr::Exists { .. }
+ | Expr::InSubquery { .. } => Ok(false),
Review Comment:
I think a`IN` can be nullable if its exprs are nullable:
```sql
alamb=# select null IN (select * from a);
?column?
----------
(1 row)
```
So maybe `Expr::InSubquery` should return `expr.nullable(input_schema)` too
##########
datafusion/core/src/sql/utils.rs:
##########
@@ -371,7 +371,17 @@ where
Expr::Column { .. }
| Expr::Literal(_)
| Expr::ScalarVariable(_, _)
- | Expr::Exists(_) => Ok(expr.clone()),
+ | Expr::Exists { .. }
+ | Expr::ScalarSubquery(_) => Ok(expr.clone()),
+ Expr::InSubquery {
+ expr: nested_expr,
+ subquery,
+ negated,
+ } => Ok(Expr::InSubquery {
+ expr: Box::new(clone_with_replacement(&**nested_expr,
replacement_fn)?),
Review Comment:
👍
##########
datafusion/expr/src/expr.rs:
##########
@@ -622,7 +656,11 @@ fn create_name(e: &Expr, input_schema: &DFSchema) ->
Result<String> {
let expr = create_name(expr, input_schema)?;
Ok(format!("{} IS NOT NULL", expr))
}
- Expr::Exists(_) => Ok("EXISTS".to_string()),
+ Expr::Exists { .. } => Ok("EXISTS".to_string()),
+ Expr::InSubquery { .. } => Ok("IN".to_string()),
Review Comment:
should this also take into account `negated`?
```suggestion
Expr::Exists { negated: true, .. } => Ok("NOT EXISTS".to_string()),
Expr::Exists { negated: false, .. } => Ok("EXISTS".to_string()),
Expr::InSubquery { negated: true, .. } => Ok("NOT IN".to_string()),
Expr::InSubquery { negated: false, .. } => Ok("IN".to_string()),
```
##########
datafusion/core/src/optimizer/simplify_expressions.rs:
##########
@@ -375,7 +375,9 @@ impl<'a> ConstEvaluator<'a> {
| Expr::AggregateUDF { .. }
| Expr::ScalarVariable(_, _)
| Expr::Column(_)
- | Expr::Exists(_)
+ | Expr::Exists { .. }
+ | Expr::InSubquery { .. }
+ | Expr::ScalarSubquery(_)
Review Comment:
at some point it would be cool to be able to evaluate scalar subqueries at
plan time, "but not now" 😆
##########
datafusion/expr/src/expr.rs:
##########
@@ -434,7 +450,25 @@ impl fmt::Debug for Expr {
Expr::Negative(expr) => write!(f, "(- {:?})", expr),
Expr::IsNull(expr) => write!(f, "{:?} IS NULL", expr),
Expr::IsNotNull(expr) => write!(f, "{:?} IS NOT NULL", expr),
- Expr::Exists(subquery) => write!(f, "EXISTS ({:?})", subquery),
+ Expr::Exists { subquery, negated } => {
+ if *negated {
+ write!(f, "NOT EXISTS ({:?})", subquery)
+ } else {
+ write!(f, "EXISTS ({:?})", subquery)
+ }
+ }
Review Comment:
I am not sure if you think this is cleaner, but you could potentially use
multiple pattern matches like this (untested)
```suggestion
Expr::Exists { subquery, negated: true } => write!(f, "NOT
EXISTS ({:?})", subquery),
Expr::Exists { subquery, negated: false } => write!(f, "EXISTS
({:?})", subquery),
```
The same comment applies for `Expr::InSubquery`
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