[ARROW-10236] [Rust] [DataFusion] Make DataFusion casting rules consistent with cast kernel

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 3.0.0
• Component/s: Rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/26234
• Assignee: Andrew Lamb
• Reporter: Andrew Lamb
• Created: 08/Oct/20 14:55
• Updated: 11/Jan/23 08:11
• Resolved: 16/Oct/20 05:12

Description

There are plan time checks for valid type casts in DataFusion that are designed to catch errors early before plan execution

Sadly the cast types that DataFusion thinks are valid is a significant subset of what the arrow cast kernel supports. The goal of this ticket is to bring DataFusion to parity with the type casting supported by arrow and allow DataFusion to plan all casts that are supported by the arrow cast kernel

(I want this implicitly so when I add support for DictionaryArray casts in Arrow they also are part of DataFusion)

Previously the notions of coercion and casting were somewhat conflated. I have tried to clarify them in https://github.com/apache/arrow/pull/8399 as well

For more detail, see https://github.com/apache/arrow/pull/8340#discussion_r501257096 from jorgecarleitao

Issue Links

• links to: GitHub Pull Request #8400
• links to: GitHub Pull Request #8460