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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/04/26 03:22:58 UTC
[GitHub] [arrow-datafusion] andygrove opened a new pull request, #2342: WIP: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
andygrove opened a new pull request, #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342
# Which issue does this PR close?
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Part of https://github.com/apache/arrow-datafusion/issues/2248
# Rationale for this change
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Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes.
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Add `InSubquery` and `ScalarSubquery` to `Expr` as a step towards supporting SQL queries that use these expressions.
# What changes are included in this PR?
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There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR.
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- Add `InSubquery` and `ScalarSubquery` to `Expr`
- Add functions to create these expressions
# Are there any user-facing changes?
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Yes, API change
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #2342: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
Posted by GitBox <gi...@apache.org>.
alamb commented on code in PR #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342#discussion_r859135158
##########
datafusion/expr/src/expr.rs:
##########
@@ -434,7 +450,26 @@ 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: true,
+ } => write!(f, "NOT EXISTS ({:?})", subquery),
+ Expr::Exists {
+ subquery,
+ negated: false,
+ } => write!(f, "EXISTS ({:?})", subquery),
+ Expr::InSubquery {
+ expr,
+ subquery,
+ negated,
+ } => {
+ if *negated {
+ write!(f, "{:?} NOT IN ({:?})", expr, subquery)
+ } else {
+ write!(f, "{:?} IN ({:?})", expr, subquery)
+ }
+ }
Review Comment:
The same `negated: true` / `negated: false` could be applied to `Expr::InSubquery` as was applied to `Expr::Exists`
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[GitHub] [arrow-datafusion] andygrove commented on a diff in pull request #2342: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
Posted by GitBox <gi...@apache.org>.
andygrove commented on code in PR #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342#discussion_r859089828
##########
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:
Thanks. Fixed.
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[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #2342: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
Posted by GitBox <gi...@apache.org>.
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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[GitHub] [arrow-datafusion] alamb commented on pull request #2342: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
Posted by GitBox <gi...@apache.org>.
alamb commented on PR #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342#issuecomment-1110838834
🎉
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[GitHub] [arrow-datafusion] andygrove merged pull request #2342: Add `Expr::InSubquery` and `Expr::ScalarSubquery`
Posted by GitBox <gi...@apache.org>.
andygrove merged PR #2342:
URL: https://github.com/apache/arrow-datafusion/pull/2342
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