[Format] Make requirement around dense union offsets less ambiguous
- Dominant language
- C++
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Description
Currently, the spec states that dense union offsets for each child array must be "in order / increasing". There is an ambiguity: should they be strictly increasing, or are equal values supported?
The C++ implementation currently considers that equal offsets are acceptable.
**Reporter**: [Antoine Pitrou](https://issues.apache.org/jira/browse/ARROW-13479) / @pitrou
**Note**: *This issue was originally created as [ARROW-13479](https://issues.apache.org/jira/browse/ARROW-13479). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*
Contributor guide
Research direction
Read the dense union specification and compare its “in order / increasing” wording with the C++ implementation's offset validation. Clarify whether equal offsets are supported, and consider the work done when the specification unambiguously states the accepted ordering.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- data
- Issue type
- Documentation
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 68/100