alamb commented on code in PR #17450:
URL: https://github.com/apache/datafusion/pull/17450#discussion_r2326050206
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1399,6 +1399,18 @@ impl<S: SimplifyInfo> TreeNodeRewriter for
Simplifier<'_, S> {
// Rules for Case
//
+ // CASE WHEN true THEN A ... END --> A
+ Expr::Case(Case {
+ expr: None,
+ when_then_expr,
+ else_expr: _,
+ }) if !when_then_expr.is_empty()
+ && matches!(when_then_expr[0].0.as_ref(),
+ Expr::Literal(ScalarValue::Boolean(Some(true)), _)) =>
Review Comment:
can we please use `is_true` to follow the pattern in the rest of this method?
https://github.com/apache/datafusion/blob/4b9a468cc1949062cf3cd8685ba8ced377fd212e/datafusion/optimizer/src/simplify_expressions/utils.rs#L193-L198
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -3552,6 +3564,61 @@ mod tests {
);
}
+ #[test]
+ fn simplify_expr_case_when_true() {
+ // CASE WHEN true THEN 1 ELSE x END --> 1
Review Comment:
can we please add some negative tests too -- like `CASE WHEN a THEN 1 ELSE
2 END`?
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1399,6 +1399,18 @@ impl<S: SimplifyInfo> TreeNodeRewriter for
Simplifier<'_, S> {
// Rules for Case
//
+ // CASE WHEN true THEN A ... END --> A
+ Expr::Case(Case {
+ expr: None,
+ when_then_expr,
+ else_expr: _,
+ }) if !when_then_expr.is_empty()
+ && matches!(when_then_expr[0].0.as_ref(),
+ Expr::Literal(ScalarValue::Boolean(Some(true)), _)) =>
+ {
+ Transformed::yes((*when_then_expr[0].1).clone())
Review Comment:
I think it would be good to avoid this clone too,
How about something like this:
```suggestion
let (when, then_) = when_then_expr.swap_remove(0);
Transformed::yes(*when)
```
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