Allow base64 encoding of fixedsizebinary arrays

Author: maxburke

datafusion/functions/src/encoding/inner.rs

@@ -29,7 +29,9 @@ use base64::{
     Engine as _,
 };
 use datafusion_common::{
-    cast::{as_generic_binary_array, as_generic_string_array},
+    cast::{
+        as_fixed_size_binary_array, as_generic_binary_array, as_generic_string_array,
+    },
     not_impl_err, plan_err,
     utils::take_function_args,
 };
@@ -246,6 +248,9 @@ fn encode_process(value: &ColumnarValue, encoding: Encoding) -> Result<ColumnarV
             DataType::Utf8View => encoding.encode_utf8_array::<i32>(a.as_ref()),
             DataType::Binary => encoding.encode_binary_array::<i32>(a.as_ref()),
             DataType::LargeBinary => encoding.encode_binary_array::<i64>(a.as_ref()),
+            DataType::FixedSizeBinary(_) => {
+                encoding.encode_fixed_size_binary_array(a.as_ref())
+            }
             other => exec_err!(
                 "Unsupported data type {other:?} for function encode({encoding})"
             ),
@@ -265,6 +270,9 @@ fn encode_process(value: &ColumnarValue, encoding: Encoding) -> Result<ColumnarV
                 ),
                 ScalarValue::LargeBinary(a) => Ok(encoding
                     .encode_large_scalar(a.as_ref().map(|v: &Vec<u8>| v.as_slice()))),
+                ScalarValue::FixedSizeBinary(_, a) => Ok(
+                    encoding.encode_scalar(a.as_ref().map(|v: &Vec<u8>| v.as_slice()))
+                ),
                 other => exec_err!(
                     "Unsupported data type {other:?} for function encode({encoding})"
                 ),
@@ -401,6 +409,15 @@ impl Encoding {
         Ok(ColumnarValue::Array(array))
     }
 
+    fn encode_fixed_size_binary_array(self, value: &dyn Array) -> Result<ColumnarValue> {
+        let input_value = as_fixed_size_binary_array(value)?;
+        let array: ArrayRef = match self {
+            Self::Base64 => encode_to_array!(base64_encode, input_value),
+            Self::Hex => encode_to_array!(hex_encode, input_value),
+        };
+        Ok(ColumnarValue::Array(array))
+    }
+
     fn encode_utf8_array<T>(self, value: &dyn Array) -> Result<ColumnarValue>
     where
         T: OffsetSizeTrait,
@@ -553,3 +570,29 @@ fn decode(args: &[ColumnarValue]) -> Result<ColumnarValue> {
     }?;
     decode_process(expression, encoding)
 }
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_encode_fsb() {
+        use super::*;
+
+        let value = vec![0u8; 16];
+        let array = arrow::array::FixedSizeBinaryArray::try_from_sparse_iter_with_size(
+            vec![Some(value)].into_iter(),
+            16,
+        )
+        .unwrap();
+        let value = ColumnarValue::Array(Arc::new(array));
+
+        let ColumnarValue::Array(result) =
+            encode_process(&value, Encoding::Base64).unwrap()
+        else {
+            panic!("unexpected value");
+        };
+
+        let string_array = result.as_any().downcast_ref::<StringArray>().unwrap();
+        let result_value = string_array.value(0);
+        assert_eq!(result_value, "AAAAAAAAAAAAAAAAAAAAAA");
+    }
+}