Rename and simplify decimal rendering functions

- add `decimal` to function name
- drop `precision` parameter as it is not supposed to affect the result

Author: findepi

datafusion/sqllogictest/src/engines/conversion.rs

@@ -81,16 +81,18 @@ pub(crate) fn f64_to_str(value: f64) -> String {
     }
 }
 
-pub(crate) fn i128_to_str(value: i128, precision: &u8, scale: &i8) -> String {
+pub(crate) fn decimal_128_to_str(value: i128, scale: i8) -> String {
+    let precision = u8::MAX; // does not matter
     big_decimal_to_str(
-        BigDecimal::from_str(&Decimal128Type::format_decimal(value, *precision, *scale))
+        BigDecimal::from_str(&Decimal128Type::format_decimal(value, precision, scale))
             .unwrap(),
     )
 }
 
-pub(crate) fn i256_to_str(value: i256, precision: &u8, scale: &i8) -> String {
+pub(crate) fn decimal_256_to_str(value: i256, scale: i8) -> String {
+    let precision = u8::MAX; // does not matter
     big_decimal_to_str(
-        BigDecimal::from_str(&Decimal256Type::format_decimal(value, *precision, *scale))
+        BigDecimal::from_str(&Decimal256Type::format_decimal(value, precision, scale))
             .unwrap(),
     )
 }

datafusion/sqllogictest/src/engines/datafusion_engine/normalize.rs

@@ -213,13 +213,13 @@ pub fn cell_to_string(col: &ArrayRef, row: usize) -> Result<String> {
             DataType::Float64 => {
                 Ok(f64_to_str(get_row_value!(array::Float64Array, col, row)))
             }
-            DataType::Decimal128(precision, scale) => {
+            DataType::Decimal128(_, scale) => {
                 let value = get_row_value!(array::Decimal128Array, col, row);
-                Ok(i128_to_str(value, precision, scale))
+                Ok(decimal_128_to_str(value, *scale))
             }
-            DataType::Decimal256(precision, scale) => {
+            DataType::Decimal256(_, scale) => {
                 let value = get_row_value!(array::Decimal256Array, col, row);
-                Ok(i256_to_str(value, precision, scale))
+                Ok(decimal_256_to_str(value, *scale))
             }
             DataType::LargeUtf8 => Ok(varchar_to_str(get_row_value!(
                 array::LargeStringArray,