fix: add string view variant and rules

Author: Cheng-Yuan-Lai

datafusion/common/src/types/builtin.rs

@@ -47,3 +47,4 @@ singleton!(LOGICAL_FLOAT64, logical_float64, Float64);
 singleton!(LOGICAL_DATE, logical_date, Date);
 singleton!(LOGICAL_BINARY, logical_binary, Binary);
 singleton!(LOGICAL_STRING, logical_string, String);
+singleton!(LOGICAL_STRING_VIEW, logical_string_view, StringView);

datafusion/common/src/types/native.rs

@@ -150,6 +150,8 @@ pub enum NativeType {
     FixedSizeBinary(i32),
     /// A variable-length string in Unicode with UTF-8 encoding.
     String,
+    /// A variable-length stringView in Unicode with UTF-8 encoding.
+    StringView,
     /// A list of some logical data type with variable length.
     List(LogicalFieldRef),
     /// A list of some logical data type with fixed length.
@@ -261,6 +263,7 @@ impl LogicalType for NativeType {
                 LargeUtf8
             }
             (Self::String, data_type) if can_cast_types(data_type, &Utf8) => Utf8,
+            (Self::StringView, _) => Utf8View,
             (Self::List(to_field), List(from_field) | FixedSizeList(from_field, _)) => {
                 List(default_field_cast(to_field, from_field)?)
             }
@@ -395,7 +398,8 @@ impl From<DataType> for NativeType {
             DataType::Interval(iu) => Interval(iu),
             DataType::Binary | DataType::LargeBinary | DataType::BinaryView => Binary,
             DataType::FixedSizeBinary(size) => FixedSizeBinary(size),
-            DataType::Utf8 | DataType::LargeUtf8 | DataType::Utf8View => String,
+            DataType::Utf8 | DataType::LargeUtf8 => String,
+            DataType::Utf8View => StringView,
             DataType::List(field)
             | DataType::ListView(field)
             | DataType::LargeList(field)

datafusion/expr-common/src/signature.rs

@@ -546,6 +546,7 @@ fn get_data_types(native_type: &NativeType) -> Vec<DataType> {
         NativeType::String => {
             vec![DataType::Utf8, DataType::LargeUtf8, DataType::Utf8View]
         }
+        NativeType::StringView => vec![DataType::Utf8View],
         // TODO: support other native types
         _ => vec![],
     }

datafusion/functions/src/crypto/digest.rs

@@ -19,7 +19,7 @@
 use super::basic::{digest, utf8_or_binary_to_binary_type};
 use arrow::datatypes::DataType;
 use datafusion_common::{
-    types::{logical_binary, logical_string},
+    types::{logical_binary, logical_string, logical_string_view, NativeType},
     Result,
 };
 use datafusion_expr::{
@@ -71,12 +71,22 @@ impl DigestFunc {
         Self {
             signature: Signature::one_of(
                 vec![
+                    // (Utf8View, Utf8View) case
                     TypeSignature::Coercible(vec![
-                        Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
-                        Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
+                        Coercion::new_exact(TypeSignatureClass::Native(
+                            logical_string_view(),
+                        )),
+                        Coercion::new_exact(TypeSignatureClass::Native(
+                            logical_string_view(),
+                        )),
                     ]),
+                    // Other cases
                     TypeSignature::Coercible(vec![
-                        Coercion::new_exact(TypeSignatureClass::Native(logical_binary())),
+                        Coercion::new_implicit(
+                            TypeSignatureClass::Native(logical_string()),
+                            vec![TypeSignatureClass::Native(logical_string())],
+                            NativeType::String,
+                        ),
                         Coercion::new_exact(TypeSignatureClass::Native(logical_string())),
                     ]),
                 ],