[Rust] [DataFusion] Implement COUNT aggregate expression

[asfimport]

Implement COUNT aggregate expressions. See the SUM implementation for inspiration.

Reporter: Andy Grove / @andygrove

PRs and other links:

• GitHub Pull Request #5513

_{Note: This issue was originally created as ARROW-6657. Please see the migration documentation for further details.}

[asfimport]

Davis Silverman:
Hi, I would be interested in completing this. I have it almost implemented, need to do null checking on the value at each row. Is the submit/review process documented anywhere? Thanks!

[asfimport]

Andy Grove / @andygrove:
I'm actually not sure if it is documented or not ... but basically all you need to do is create a PR from your fork and use a title like "ARROW-6657: [Rust] [DataFusion] Implement COUNT in physical query plan" and add the labels "lang-rust" and "datafusion".

You can request reviews too from the Rust committers ... for the DataFusion crate that is mostly me, Paddy Horan and nevi-me right now.

 

 

 

 

 

 

[asfimport]

Wes McKinney / @wesm:
https://github.com/apache/arrow/blob/master/docs/source/developers/contributing.rst

[asfimport]

Andy Grove / @andygrove:
Issue resolved by pull request 5513
#5513