[Rust] Add support for decimal data type

[asfimport]

We should add Decimal(usize,usize) to DataType and add the corresponding array and builder classes.

 

Reporter: Andy Grove / @andygrove
Assignee: Florian Müller / @sweb

PRs and other links:

• GitHub Pull Request #8640

_{Note: This issue was originally created as ARROW-4193. Please see the migration documentation for further details.}

[asfimport]

Florian Müller / @sweb:
I would like to work on this issue. However, I currently don't quite understand why decimal values are encoded as fixed size binary arrays of size 10 when reading from parquet. I am able to reconstruct the decimal value when I omit the first two bytes, but this feels very fishy to me.

Could you point me in the direction of some documentation or existing implementation as to how I can properly decode a decimal value?

 

Cheers!

[asfimport]

Jorge Leitão / @jorgecarleitao:
Issue resolved by pull request 8640
#8640