alamb commented on code in PR #13260:
URL: https://github.com/apache/datafusion/pull/13260#discussion_r1831473963
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1470,34 +1471,67 @@ impl<'a, S: SimplifyInfo> TreeNodeRewriter for
Simplifier<'a, S> {
}) => Transformed::yes(simplify_regex_expr(left, op, right)?),
// Rules for Like
- Expr::Like(Like {
- expr,
- pattern,
- negated,
- escape_char: _,
- case_insensitive: _,
- }) if matches!(
- pattern.as_ref(),
- Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) if
pattern_str == "%"
- ) || matches!(
- pattern.as_ref(),
- Expr::Literal(ScalarValue::LargeUtf8(Some(pattern_str))) if
pattern_str == "%"
- ) || matches!(
- pattern.as_ref(),
- Expr::Literal(ScalarValue::Utf8View(Some(pattern_str))) if
pattern_str == "%"
- ) =>
- {
- // exp LIKE '%' is
- // - when exp is not NULL, it's true
- // - when exp is NULL, it's NULL
- // exp NOT LIKE '%' is
- // - when exp is not NULL, it's false
- // - when exp is NULL, it's NULL
- Transformed::yes(Expr::Case(Case {
- expr: Some(Box::new(Expr::IsNotNull(expr))),
- when_then_expr: vec![(Box::new(lit(true)),
Box::new(lit(!negated)))],
- else_expr: None,
- }))
+ Expr::Like(like) => {
+ match as_string_scalar(&like.pattern) {
+ Some((data_type, pattern_str)) => {
+ match pattern_str {
+ None => return
Ok(Transformed::yes(lit_bool_null())),
+ Some(pattern_str) if pattern_str == "%" => {
+ // exp LIKE '%' is
+ // - when exp is not NULL, it's true
+ // - when exp is NULL, it's NULL
+ // exp NOT LIKE '%' is
+ // - when exp is not NULL, it's false
+ // - when exp is NULL, it's NULL
+ let result_for_non_null = lit(!like.negated);
+ Transformed::yes(if
!info.nullable(&like.expr)? {
+ result_for_non_null
+ } else {
+ Expr::Case(Case {
+ expr:
Some(Box::new(Expr::IsNotNull(like.expr))),
+ when_then_expr: vec![(
+ Box::new(lit(true)),
+ Box::new(result_for_non_null),
+ )],
+ else_expr: None,
+ })
+ })
+ }
+ Some(pattern_str)
Review Comment:
```suggestion
Some(pattern_str)
// Repeated occurrences of wildcard are
redundant so remove them
// exp LIKE '%%' --> exp LIKE '%'
```
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