[ARROW-8919] [C++] Add "DispatchBest" APIs to compute::Function that selects a kernel that may require implicit casts to invoke

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 4.0.0
• Component/s: C++
• Labels: compute pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/25050
• Assignee: Ben Kietzman
• Reporter: Wes McKinney
• Created: 24/May/20 13:09
• Updated: 11/Jan/23 08:03
• Resolved: 10/Feb/21 20:48

Description

Currently we have "DispatchExact" which requires an exact match of input types. "DispatchBest" would permit kernel selection with implicit casts required. Since multiple kernels may be valid when allowing implicit casts, we will need to break ties by estimating the "cost" of the implicit casts. For example, casting int8 to int32 is "less expensive" than implicitly casting to int64

Issue Links

• is a child of: ARROW-8894 [C++] C++ array kernels framework and execution buildout (umbrella issue)
• is duplicated by: ARROW-11078 [C++] Implement autocasting in arithmetic compute kernels
• is duplicated by: ARROW-11080 [C++][Dataset] Improvements to implicit casting
• relates to: ARROW-8901 [C++] Reduce number of take kernels
• relates to: ARROW-8905 [C++] Collapse Take APIs from 8 to 1 or 2
• links to: GitHub Pull Request #9294