ovr commented on a change in pull request #9232:
URL: https://github.com/apache/arrow/pull/9232#discussion_r561946613
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File path: rust/arrow/src/datatypes/mod.rs
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@@ -199,6 +207,81 @@ pub struct Field {
metadata: Option<BTreeMap<String, String>>,
}
+// Decimal (precision, scale) = Decimal(1, 2) = 1.00
+pub trait ArrowDecimalType: fmt::Debug + Send + Sync + FromStr + PartialEq {
+ const MAX_DIGITS: usize;
+
+ // fn into_json_value(self) -> Option<Value>;
+
+ fn get_byte_width_for_precision_scale(precision: usize, scale: usize) ->
usize;
+
+ // Rescale scale part
+ fn rescale(&mut self, scale: usize);
+
+ // Try to parse string with precision, scale
+ fn parse(
+ string: &str,
+ precision: usize,
+ scale: usize,
+ ) -> std::result::Result<Self, ParseDecimalError>;
+
+ fn to_byte_slice(&self) -> Vec<u8>;
+
+ fn from_bytes_with_precision_scale(
+ bytes: &[u8],
+ precision: usize,
+ scale: usize,
+ ) -> Self;
+}
+
+#[derive(Debug)]
+pub enum DecimalType {
Review comment:
@alamb @andygrove @Dandandan @nevi-me @jorgecarleitao
I created representations for Decimal as `Int32DecimalType`,
`Int64DecimalType`, `Int128DecimalType` or `LargeDecimal`, which uses BigInt.
1. What is the best way in Rust to abstract representations of
`DataType::Decimal` in Rust? Enum?
2. How should I work with `DecimalArray`? Should I make it as generic by
passing representation type to it (but how should I detect type, match in
everyplace? As I have known functions cannot return type) or make it generic on
top of DecimalType and get byte size from it?
Thanks
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