Fix max and min value for decimal256

arrow/src/array/builder/decimal_builder.rs

@@ -261,7 +261,7 @@ mod tests {
     use crate::array::array_decimal::{BasicDecimalArray, Decimal128Array};
     use crate::array::{array_decimal, Array};
     use crate::datatypes::DataType;
-    use crate::util::decimal::Decimal128;
+    use crate::util::decimal::{Decimal128, Decimal256};
 
     #[test]
     fn test_decimal_builder() {
@@ -357,31 +357,29 @@ mod tests {
 
     #[test]
     #[should_panic(
-        expected = "9999999999999999999999999999999999999999999999999999999999999999999999999999 is too large to store in a Decimal256 of precision 76. Max is 999999999999999999999999999999999999999999999999999999999999999999999999999"
+        expected = "9999999999999999999999999999999999999999999999999999999999999999999999999999 is too large to store in a Decimal256 of precision 75. Max is 999999999999999999999999999999999999999999999999999999999999999999999999999"
     )]
     fn test_decimal256_builder_out_of_range_precision_scale() {
-        let mut builder = Decimal256Builder::new(30, 76, 6);
+        let mut builder = Decimal256Builder::new(30, 75, 6);
 
         let big_value = BigInt::from_str_radix("9999999999999999999999999999999999999999999999999999999999999999999999999999", 10).unwrap();
-        let bytes = big_value.to_signed_bytes_le();
-        let value = Decimal256::try_new_from_bytes(76, 6, &bytes).unwrap();
+        let value = Decimal256::from_big_int(&big_value, 75, 6).unwrap();
         builder.append_value(&value).unwrap();
     }
 
     #[test]
     #[should_panic(
-        expected = "9999999999999999999999999999999999999999999999999999999999999999999999999999 is too large to store in a Decimal256 of precision 76. Max is 999999999999999999999999999999999999999999999999999999999999999999999999999"
+        expected = "9999999999999999999999999999999999999999999999999999999999999999999999999999 is too large to store in a Decimal256 of precision 75. Max is 999999999999999999999999999999999999999999999999999999999999999999999999999"
     )]
     fn test_decimal256_data_validation() {
-        let mut builder = Decimal256Builder::new(30, 76, 6);
+        let mut builder = Decimal256Builder::new(30, 75, 6);
         // Disable validation at builder
         unsafe {
             builder.disable_value_validation();
         }
 
         let big_value = BigInt::from_str_radix("9999999999999999999999999999999999999999999999999999999999999999999999999999", 10).unwrap();
-        let bytes = big_value.to_signed_bytes_le();
-        let value = Decimal256::try_new_from_bytes(76, 6, &bytes).unwrap();
+        let value = Decimal256::from_big_int(&big_value, 75, 6).unwrap();
         builder
             .append_value(&value)
             .expect("should not validate invalid value at builder");

arrow/src/datatypes/datatype.rs

@@ -309,7 +309,6 @@ pub const MAX_DECIMAL_FOR_EACH_PRECISION: [i128; 38] = [
 /// `MAX_DECIMAL_FOR_LARGER_PRECISION[p]` holds the maximum integer value
 /// that can be stored in [DataType::Decimal256] value of precision `p` > 38
 pub const MAX_DECIMAL_FOR_LARGER_PRECISION: [&str; 38] = [
-    "99999999999999999999999999999999999999",
     "999999999999999999999999999999999999999",
     "9999999999999999999999999999999999999999",
     "99999999999999999999999999999999999999999",
@@ -347,6 +346,7 @@ pub const MAX_DECIMAL_FOR_LARGER_PRECISION: [&str; 38] = [
     "9999999999999999999999999999999999999999999999999999999999999999999999999",
     "99999999999999999999999999999999999999999999999999999999999999999999999999",
     "999999999999999999999999999999999999999999999999999999999999999999999999999",
+    "9999999999999999999999999999999999999999999999999999999999999999999999999999",
 ];
 
 /// `MIN_DECIMAL_FOR_EACH_PRECISION[p]` holds the minimum `i128` value
@@ -395,7 +395,6 @@ pub const MIN_DECIMAL_FOR_EACH_PRECISION: [i128; 38] = [
 /// `MIN_DECIMAL_FOR_LARGER_PRECISION[p]` holds the minimum integer value
 /// that can be stored in a [DataType::Decimal256] value of precision `p` > 38
 pub const MIN_DECIMAL_FOR_LARGER_PRECISION: [&str; 38] = [
-    "-99999999999999999999999999999999999999",
     "-999999999999999999999999999999999999999",
     "-9999999999999999999999999999999999999999",
     "-99999999999999999999999999999999999999999",
@@ -433,6 +432,7 @@ pub const MIN_DECIMAL_FOR_LARGER_PRECISION: [&str; 38] = [
     "-9999999999999999999999999999999999999999999999999999999999999999999999999",
     "-99999999999999999999999999999999999999999999999999999999999999999999999999",
     "-999999999999999999999999999999999999999999999999999999999999999999999999999",
+    "-9999999999999999999999999999999999999999999999999999999999999999999999999999",
 ];
 
 /// The maximum precision for [DataType::Decimal128] values
@@ -454,22 +454,24 @@ pub const DECIMAL_DEFAULT_SCALE: usize = 10;
 /// interpreted as a Decimal number with precision `precision`
 #[inline]
 pub(crate) fn validate_decimal_precision(value: i128, precision: usize) -> Result<i128> {
-    // TODO: add validation logic for precision > 38
-    if precision > 38 {
-        return Ok(value);
+    if precision > DECIMAL128_MAX_PRECISION {
+        return Err(ArrowError::InvalidArgumentError(format!(
+            "Max precision of a Decimal128 is {}, but got {}",
+            DECIMAL128_MAX_PRECISION, precision,
+        )));
     }
 
     let max = MAX_DECIMAL_FOR_EACH_PRECISION[precision - 1];
     let min = MIN_DECIMAL_FOR_EACH_PRECISION[precision - 1];
 
     if value > max {
         Err(ArrowError::InvalidArgumentError(format!(
-            "{} is too large to store in a Decimal of precision {}. Max is {}",
+            "{} is too large to store in a Decimal128 of precision {}. Max is {}",
             value, precision, max
         )))
     } else if value < min {
         Err(ArrowError::InvalidArgumentError(format!(
-            "{} is too small to store in a Decimal of precision {}. Min is {}",
+            "{} is too small to store in a Decimal128 of precision {}. Min is {}",
             value, precision, min
         )))
     } else {