replace type signature for starts_with

Author: zjregee

datafusion/expr/src/lib.rs

@@ -76,7 +76,7 @@ pub use datafusion_expr_common::columnar_value::ColumnarValue;
 pub use datafusion_expr_common::groups_accumulator::{EmitTo, GroupsAccumulator};
 pub use datafusion_expr_common::operator::Operator;
 pub use datafusion_expr_common::signature::{
-    ArrayFunctionArgument, ArrayFunctionSignature, Signature, TypeSignature,
+    ArrayFunctionArgument, ArrayFunctionSignature, Coercion, Signature, TypeSignature,
     TypeSignatureClass, Volatility, TIMEZONE_WILDCARD,
 };
 pub use datafusion_expr_common::type_coercion::binary;

datafusion/functions/src/string/starts_with.rs

@@ -23,9 +23,12 @@ use arrow::datatypes::DataType;
 use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyInfo};
 
 use crate::utils::make_scalar_function;
+use datafusion_common::types::logical_string;
 use datafusion_common::{internal_err, Result, ScalarValue};
-use datafusion_expr::{ColumnarValue, Documentation, Expr, Like};
-use datafusion_expr::{ScalarFunctionArgs, ScalarUDFImpl, Signature, Volatility};
+use datafusion_expr::{
+    Coercion, ColumnarValue, Documentation, Expr, Like, ScalarFunctionArgs,
+    ScalarUDFImpl, Signature, TypeSignatureClass, Volatility,
+};
 use datafusion_macros::user_doc;
 
 /// Returns true if string starts with prefix.
@@ -64,7 +67,13 @@ impl Default for StartsWithFunc {
 impl StartsWithFunc {
     pub fn new() -> Self {
         Self {
-            signature: Signature::string(2, Volatility::Immutable),
+            signature: Signature::coercible(
+                vec![
+                    Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
+                    Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
+                ],
+                Volatility::Immutable,
+            ),
         }
     }
 }