Copy over changes from PR #20581

petern48 · petern48 · commit dfb3080512be · 2026-03-01T13:24:39.000-08:00
diff --git a/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs b/datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs
@@ -1660,17 +1660,19 @@ impl TreeNodeRewriter for Simplifier<'_> {
                 left,
                 op: op @ (RegexMatch | RegexNotMatch | RegexIMatch | RegexNotIMatch),
                 right,
-            }) => Transformed::yes(simplify_regex_expr(left, op, right)?),
+            }) => simplify_regex_expr(left, op, right)?,
 
             // Rules for Like
             Expr::Like(like) => {
                 // `\` is implicit escape, see https://github.com/apache/datafusion/issues/13291
                 let escape_char = like.escape_char.unwrap_or('\\');
-                match as_string_scalar(&like.pattern) {
-                    Some((data_type, pattern_str)) => {
+
+                match StringScalar::try_from_expr(&like.pattern) {
+                    Some(string_scalar) => {
+                        let pattern_str = string_scalar.as_str();
                         match pattern_str {
                             None => return Ok(Transformed::yes(lit_bool_null())),
-                            Some(pattern_str) if pattern_str == "%" => {
+                            Some("%") => {
                                 // exp LIKE '%' is
                                 //   - when exp is not NULL, it's true
                                 //   - when exp is NULL, it's NULL
@@ -1702,10 +1704,9 @@ impl TreeNodeRewriter for Simplifier<'_> {
                                     .replace_all(pattern_str, "%")
                                     .to_string();
                                 Transformed::yes(Expr::Like(Like {
-                                    pattern: Box::new(to_string_scalar(
-                                        &data_type,
-                                        Some(simplified_pattern),
-                                    )),
+                                    pattern: Box::new(
+                                        string_scalar.to_expr(&simplified_pattern),
+                                    ),
                                     ..like
                                 }))
                             }
@@ -2126,21 +2127,54 @@ fn is_literal_or_literal_cast(expr: &Expr) -> bool {
     }
 }
 
-fn as_string_scalar(expr: &Expr) -> Option<(DataType, &Option<String>)> {
-    match expr {
-        Expr::Literal(ScalarValue::Utf8(s), _) => Some((DataType::Utf8, s)),
-        Expr::Literal(ScalarValue::LargeUtf8(s), _) => Some((DataType::LargeUtf8, s)),
-        Expr::Literal(ScalarValue::Utf8View(s), _) => Some((DataType::Utf8View, s)),
-        _ => None,
-    }
+/// Helper for working with string scalar values (Utf8, LargeUtf8, Utf8View)
+pub(crate) enum StringScalar<'a> {
+    Utf8(&'a ScalarValue),
+    LargeUtf8(&'a ScalarValue),
+    Utf8View(&'a ScalarValue),
 }
 
-fn to_string_scalar(data_type: &DataType, value: Option<String>) -> Expr {
-    match data_type {
-        DataType::Utf8 => Expr::Literal(ScalarValue::Utf8(value), None),
-        DataType::LargeUtf8 => Expr::Literal(ScalarValue::LargeUtf8(value), None),
-        DataType::Utf8View => Expr::Literal(ScalarValue::Utf8View(value), None),
-        _ => unreachable!(),
+impl<'a> StringScalar<'a> {
+    /// Create a `StringScalar` view from an `Expr` if it is a supported string literal.
+    /// Returns `None` if the expression is not a string literal.
+    pub(crate) fn try_from_expr(expr: &'a Expr) -> Option<Self> {
+        match expr {
+            Expr::Literal(scalar, _) => Self::try_from_scalar(scalar),
+            _ => None,
+        }
+    }
+
+    /// Create a `StringScalar` view from a `ScalarValue` if it is a supported string type.
+    /// Returns `None` if the scalar value is not a supported string type.
+    fn try_from_scalar(scalar: &'a ScalarValue) -> Option<Self> {
+        match scalar {
+            ScalarValue::Utf8(_) => Some(Self::Utf8(scalar)),
+            ScalarValue::LargeUtf8(_) => Some(Self::LargeUtf8(scalar)),
+            ScalarValue::Utf8View(_) => Some(Self::Utf8View(scalar)),
+            _ => None,
+        }
+    }
+
+    /// Returns the underlying string slice.
+    pub(crate) fn as_str(&self) -> Option<&'a str> {
+        match self {
+            Self::Utf8(scalar) | Self::LargeUtf8(scalar) | Self::Utf8View(scalar) => {
+                scalar.try_as_str().flatten()
+            }
+        }
+    }
+
+    /// Build a new `Expr` of the same string type with the given value.
+    pub(crate) fn to_expr(&self, val: &str) -> Expr {
+        match self {
+            Self::Utf8(_) => Expr::Literal(ScalarValue::Utf8(Some(val.to_owned())), None),
+            Self::LargeUtf8(_) => {
+                Expr::Literal(ScalarValue::LargeUtf8(Some(val.to_owned())), None)
+            }
+            Self::Utf8View(_) => {
+                Expr::Literal(ScalarValue::Utf8View(Some(val.to_owned())), None)
+            }
+        }
     }
 }
 
diff --git a/datafusion/optimizer/src/simplify_expressions/regex.rs b/datafusion/optimizer/src/simplify_expressions/regex.rs
@@ -15,10 +15,13 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use datafusion_common::{DataFusionError, Result, ScalarValue};
+use datafusion_common::tree_node::Transformed;
+use datafusion_common::{DataFusionError, Result};
 use datafusion_expr::{BinaryExpr, Expr, Like, Operator, lit};
 use regex_syntax::hir::{Capture, Hir, HirKind, Literal, Look};
 
+use crate::simplify_expressions::expr_simplifier::StringScalar;
+
 /// Maximum number of regex alternations (`foo|bar|...`) that will be expanded into multiple `LIKE` expressions.
 const MAX_REGEX_ALTERNATIONS_EXPANSION: usize = 4;
 
@@ -43,52 +46,70 @@ pub fn simplify_regex_expr(
     left: Box<Expr>,
     op: Operator,
     right: Box<Expr>,
-) -> Result<Expr> {
-    let mode = OperatorMode::new(&op);
+) -> Result<Transformed<Expr>> {
+    // Check if the right operand is a supported string literal
+    let Some(string_scalar) = StringScalar::try_from_expr(right.as_ref()) else {
+        return Ok(Transformed::no(Expr::BinaryExpr(BinaryExpr {
+            left,
+            op,
+            right,
+        })));
+    };
+    let pattern = string_scalar.as_str();
+    let Some(pattern) = pattern else {
+        return Ok(Transformed::no(Expr::BinaryExpr(BinaryExpr {
+            left,
+            op,
+            right,
+        })));
+    };
 
-    if let Expr::Literal(ScalarValue::Utf8(Some(pattern)), _) = right.as_ref() {
-        // Handle the special case for ".*" pattern
-        if pattern == ANY_CHAR_REGEX_PATTERN {
-            let new_expr = if mode.not {
-                // not empty
-                let empty_lit = Box::new(lit(""));
-                Expr::BinaryExpr(BinaryExpr {
-                    left,
-                    op: Operator::Eq,
-                    right: empty_lit,
-                })
-            } else {
-                // not null
-                left.is_not_null()
-            };
-            return Ok(new_expr);
-        }
+    let mode = OperatorMode::new(&op);
+    // Handle the special case for ".*" pattern
+    if pattern == ANY_CHAR_REGEX_PATTERN {
+        let new_expr = if mode.not {
+            // not empty
+            let empty_lit = Box::new(string_scalar.to_expr(""));
+            Expr::BinaryExpr(BinaryExpr {
+                left,
+                op: Operator::Eq,
+                right: empty_lit,
+            })
+        } else {
+            // not null
+            left.is_not_null()
+        };
+        return Ok(Transformed::yes(new_expr));
+    }
 
-        match regex_syntax::Parser::new().parse(pattern) {
-            Ok(hir) => {
-                let kind = hir.kind();
-                if let HirKind::Alternation(alts) = kind {
-                    if alts.len() <= MAX_REGEX_ALTERNATIONS_EXPANSION
-                        && let Some(expr) = lower_alt(&mode, &left, alts)
-                    {
-                        return Ok(expr);
-                    }
-                } else if let Some(expr) = lower_simple(&mode, &left, &hir) {
-                    return Ok(expr);
+    match regex_syntax::Parser::new().parse(pattern) {
+        Ok(hir) => {
+            let kind = hir.kind();
+            if let HirKind::Alternation(alts) = kind {
+                if alts.len() <= MAX_REGEX_ALTERNATIONS_EXPANSION
+                    && let Some(expr) = lower_alt(&mode, &left, alts, &string_scalar)
+                {
+                    return Ok(Transformed::yes(expr));
                 }
-            }
-            Err(e) => {
-                // error out early since the execution may fail anyways
-                return Err(DataFusionError::Context(
-                    "Invalid regex".to_owned(),
-                    Box::new(DataFusionError::External(Box::new(e))),
-                ));
+            } else if let Some(expr) = lower_simple(&mode, &left, &hir, &string_scalar) {
+                return Ok(Transformed::yes(expr));
             }
         }
+        Err(e) => {
+            // error out early since the execution may fail anyways
+            return Err(DataFusionError::Context(
+                "Invalid regex".to_owned(),
+                Box::new(DataFusionError::External(Box::new(e))),
+            ));
+        }
     }
 
     // Leave untouched if optimization didn't work
-    Ok(Expr::BinaryExpr(BinaryExpr { left, op, right }))
+    Ok(Transformed::no(Expr::BinaryExpr(BinaryExpr {
+        left,
+        op,
+        right,
+    })))
 }
 
 #[derive(Debug)]
@@ -117,11 +138,11 @@ impl OperatorMode {
     }
 
     /// Creates an [`LIKE`](Expr::Like) from the given `LIKE` pattern.
-    fn expr(&self, expr: Box<Expr>, pattern: String) -> Expr {
+    fn expr(&self, expr: Box<Expr>, pattern: Box<Expr>) -> Expr {
         let like = Like {
             negated: self.not,
             expr,
-            pattern: Box::new(Expr::Literal(ScalarValue::from(pattern), None)),
+            pattern,
             escape_char: None,
             case_insensitive: self.i,
         };
@@ -311,14 +332,24 @@ fn anchored_alternation_to_exprs(v: &[Hir]) -> Option<Vec<Expr>> {
 }
 
 /// Tries to lower (transform) a simple regex pattern to a LIKE expression.
-fn lower_simple(mode: &OperatorMode, left: &Expr, hir: &Hir) -> Option<Expr> {
+fn lower_simple(
+    mode: &OperatorMode,
+    left: &Expr,
+    hir: &Hir,
+    string_scalar: &StringScalar,
+) -> Option<Expr> {
     match hir.kind() {
         HirKind::Empty => {
-            return Some(mode.expr(Box::new(left.clone()), "%".to_owned()));
+            return Some(
+                mode.expr(Box::new(left.clone()), Box::new(string_scalar.to_expr("%"))),
+            );
         }
         HirKind::Literal(l) => {
             let s = like_str_from_literal(l)?;
-            return Some(mode.expr(Box::new(left.clone()), format!("%{s}%")));
+            return Some(mode.expr(
+                Box::new(left.clone()),
+                Box::new(string_scalar.to_expr(&format!("%{s}%"))),
+            ));
         }
         HirKind::Concat(inner) if is_anchored_literal(inner) => {
             return anchored_literal_to_expr(inner).map(|right| {
@@ -333,7 +364,10 @@ fn lower_simple(mode: &OperatorMode, left: &Expr, hir: &Hir) -> Option<Expr> {
             if let Some(pattern) = partial_anchored_literal_to_like(inner)
                 .or_else(|| collect_concat_to_like_string(inner))
             {
-                return Some(mode.expr(Box::new(left.clone()), pattern));
+                return Some(mode.expr(
+                    Box::new(left.clone()),
+                    Box::new(string_scalar.to_expr(&pattern)),
+                ));
             }
         }
         _ => {}
@@ -344,11 +378,16 @@ fn lower_simple(mode: &OperatorMode, left: &Expr, hir: &Hir) -> Option<Expr> {
 /// Calls [`lower_simple`] for each alternative and combine the results with `or` or `and`
 /// based on [`OperatorMode`]. Any fail attempt to lower an alternative will makes this
 /// function to return `None`.
-fn lower_alt(mode: &OperatorMode, left: &Expr, alts: &[Hir]) -> Option<Expr> {
+fn lower_alt(
+    mode: &OperatorMode,
+    left: &Expr,
+    alts: &[Hir],
+    string_scalar: &StringScalar,
+) -> Option<Expr> {
     let mut accu: Option<Expr> = None;
 
     for part in alts {
-        if let Some(expr) = lower_simple(mode, left, part) {
+        if let Some(expr) = lower_simple(mode, left, part, string_scalar) {
             accu = match accu {
                 Some(accu) => {
                     if mode.not {
diff --git a/datafusion/sqllogictest/test_files/simplify_expr.slt b/datafusion/sqllogictest/test_files/simplify_expr.slt
@@ -34,20 +34,20 @@ query TT
 explain select b from t where b ~ '.*'
 ----
 logical_plan
-01)Filter: t.b ~ Utf8View(".*")
+01)Filter: t.b IS NOT NULL
 02)--TableScan: t projection=[b]
 physical_plan
-01)FilterExec: b@0 ~ .*
+01)FilterExec: b@0 IS NOT NULL
 02)--DataSourceExec: partitions=1, partition_sizes=[1]
 
 query TT
 explain select b from t where b !~ '.*'
 ----
 logical_plan
-01)Filter: t.b !~ Utf8View(".*")
+01)Filter: t.b = Utf8View("")
 02)--TableScan: t projection=[b]
 physical_plan
-01)FilterExec: b@0 !~ .*
+01)FilterExec: b@0 =
 02)--DataSourceExec: partitions=1, partition_sizes=[1]
 
 query T
diff --git a/datafusion/sqllogictest/test_files/string/string_view.slt b/datafusion/sqllogictest/test_files/string/string_view.slt
@@ -1100,7 +1100,7 @@ EXPLAIN SELECT
 FROM test;
 ----
 logical_plan
-01)Projection: test.column1_utf8view ~ Utf8View("an") AS c1
+01)Projection: test.column1_utf8view LIKE Utf8View("%an%") AS c1
 02)--TableScan: test projection=[column1_utf8view]
 
 # `~*` operator (regex match case-insensitive)
