Implemented simplify for the starts_with function to convert it into a LIKE expression.

datafusion/functions/src/string/starts_with.rs

@@ -20,10 +20,11 @@ use std::sync::Arc;
 
 use arrow::array::ArrayRef;
 use arrow::datatypes::DataType;
+use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyInfo};
 
 use crate::utils::make_scalar_function;
-use datafusion_common::{internal_err, Result};
-use datafusion_expr::{ColumnarValue, Documentation};
+use datafusion_common::{internal_err, Result, ScalarValue};
+use datafusion_expr::{ColumnarValue, Documentation, Expr, Like};
 use datafusion_expr::{ScalarUDFImpl, Signature, Volatility};
 use datafusion_macros::user_doc;
 
@@ -98,6 +99,48 @@ impl ScalarUDFImpl for StartsWithFunc {
         }
     }
 
+    fn simplify(
+        &self,
+        args: Vec<Expr>,
+        _info: &dyn SimplifyInfo,
+    ) -> Result<ExprSimplifyResult> {
+        if let Expr::Literal(scalar_value) = &args[1] {
+            // Convert starts_with(col, 'prefix') to col LIKE 'prefix%' with proper escaping
+            // Example: starts_with(col, 'ja%') -> col LIKE 'ja\%%'
+            //   1. 'ja%'         (input pattern)
+            //   2. 'ja\%'        (escape special char '%')
+            //   3. 'ja\%%'       (add suffix for starts_with)
+            let like_expr = match scalar_value {
+                ScalarValue::Utf8(Some(pattern)) => {
+                    let escaped_pattern = pattern.replace("%", "\\%");
+                    let like_pattern = format!("{}%", escaped_pattern);
+                    Expr::Literal(ScalarValue::Utf8(Some(like_pattern)))
+                }
+                ScalarValue::LargeUtf8(Some(pattern)) => {
+                    let escaped_pattern = pattern.replace("%", "\\%");
+                    let like_pattern = format!("{}%", escaped_pattern);
+                    Expr::Literal(ScalarValue::LargeUtf8(Some(like_pattern)))
+                }
+                ScalarValue::Utf8View(Some(pattern)) => {
+                    let escaped_pattern = pattern.replace("%", "\\%");
+                    let like_pattern = format!("{}%", escaped_pattern);
+                    Expr::Literal(ScalarValue::Utf8View(Some(like_pattern)))
+                }
+                _ => return Ok(ExprSimplifyResult::Original(args)),
+            };
+
+            return Ok(ExprSimplifyResult::Simplified(Expr::Like(Like {
+                negated: false,
+                expr: Box::new(args[0].clone()),
+                pattern: Box::new(like_expr),
+                escape_char: None,
+                case_insensitive: false,
+            })));
+        }
+
+        Ok(ExprSimplifyResult::Original(args))
+    }
+
     fn documentation(&self) -> Option<&Documentation> {
         self.doc()
     }

datafusion/sqllogictest/test_files/string/string_view.slt

@@ -344,7 +344,7 @@ EXPLAIN SELECT
 FROM test;
 ----
 logical_plan
-01)Projection: starts_with(test.column1_utf8view, Utf8View("äöüß")) AS c1, starts_with(test.column1_utf8view, Utf8View("")) AS c2, starts_with(test.column1_utf8view, Utf8View(NULL)) AS c3, starts_with(Utf8View(NULL), test.column1_utf8view) AS c4
+01)Projection: test.column1_utf8view LIKE Utf8View("äöüß%") AS c1, CASE test.column1_utf8view IS NOT NULL WHEN Boolean(true) THEN Boolean(true) END AS c2, starts_with(test.column1_utf8view, Utf8View(NULL)) AS c3, starts_with(Utf8View(NULL), test.column1_utf8view) AS c4
 02)--TableScan: test projection=[column1_utf8view]
 
 query TT
@@ -887,7 +887,7 @@ EXPLAIN SELECT
 FROM test;
 ----
 logical_plan
-01)Projection: starts_with(test.column1_utf8view, Utf8View("foo")) AS c, starts_with(test.column1_utf8view, test.column2_utf8view) AS c2
+01)Projection: test.column1_utf8view LIKE Utf8View("foo%") AS c, starts_with(test.column1_utf8view, test.column2_utf8view) AS c2
 02)--TableScan: test projection=[column1_utf8view, column2_utf8view]
 
 ## Ensure no casts for TRANSLATE