alamb commented on code in PR #14119:
URL: https://github.com/apache/datafusion/pull/14119#discussion_r1925978743


##########
datafusion/functions/src/string/starts_with.rs:
##########
@@ -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

Review Comment:
   I double checked the escaping logic and I think this looks good to me. 
   
   



##########
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

Review Comment:
   this is actually pretty cool -- it figured out that 
`STARTS_WITH(column1_utf8view, '') as c2,` is true if `column1_utf8view` is NOT 
NULL



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