findepi commented on code in PR #13061:
URL: https://github.com/apache/datafusion/pull/13061#discussion_r1827434320
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1470,19 +1470,25 @@ 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 !is_null(&expr)
- && matches!(
- pattern.as_ref(),
- Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) if
pattern_str == "%"
- ) =>
- {
- Transformed::yes(lit(!negated))
+ Expr::Like(ref like_expr) => {
+ if let Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) =
+ like_expr.pattern.as_ref()
+ {
+ if !is_null(&like_expr.expr) && pattern_str == "%" {
+ Transformed::yes(lit(!like_expr.negated))
+ } else if !pattern_str.contains(['%', '_'].as_ref()) {
+ // If the pattern does not contain any wildcards, we
can simplify the like expression to an equality expression
Review Comment:
Add TODO to handle escaped search characters in a follow-up.
Escaped wildcards are not uncommon in certain scenarios - eg correct use of
JDBC DatabaseMetaData will produce LIKE `foo\_bar` when inspecting object
`foo_bar`.
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -1470,19 +1470,25 @@ 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 !is_null(&expr)
- && matches!(
- pattern.as_ref(),
- Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) if
pattern_str == "%"
- ) =>
- {
- Transformed::yes(lit(!negated))
+ Expr::Like(ref like_expr) => {
+ if let Expr::Literal(ScalarValue::Utf8(Some(pattern_str))) =
+ like_expr.pattern.as_ref()
+ {
+ if !is_null(&like_expr.expr) && pattern_str == "%" {
+ Transformed::yes(lit(!like_expr.negated))
Review Comment:
I don't think this is correct. Did you consider
https://github.com/apache/datafusion/pull/13061#discussion_r1824014515 ?
##########
datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs:
##########
@@ -3632,6 +3638,16 @@ mod tests {
let expr = not_ilike(null, "%");
assert_eq!(simplify(expr), lit_bool_null());
+
+ // test cases that get converted to equality
+ let expr = like(col("c1"), "a");
+ assert_eq!(simplify(expr), col("c1").eq(lit("a")));
+ let expr = not_like(col("c1"), "a");
+ assert_eq!(simplify(expr), col("c1").not_eq(lit("a")));
+ let expr = like(col("c1"), "a_");
+ assert_eq!(simplify(expr), col("c1").like(lit("a_")));
+ let expr = not_like(col("c1"), "a_");
+ assert_eq!(simplify(expr), col("c1").not_like(lit("a_")));
Review Comment:
add a test cases where pattern is constant NULL (it won't be simplified
today, that's fine)
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