Add documentation for UNION schema handling.#17248
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| merged.retain(|k, v| input.get(k) == Some(&*v)); | ||
| } | ||
| merged | ||
| intersect_for_union(inputs) |
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Note that at construction, we handle the schema by intersection.
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since this function just calls another one, I think we could remove this one and call the other
| /// | ||
| /// ## Schema and Field Handling in Union Coercion | ||
| /// |
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Note that here in the analyzer, we handle union coercion differently than at construction.
| } | ||
| } | ||
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| /// The metadata used in [`Field::metadata`]. |
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It would be good to describe the key and value, ideally with some example
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As we move to working with more field metadata, maybe should move this function into its own module -- datafusion/expr/src/metadata.rs or something 🤔
As a follow on PR
| /// # Returns | ||
| /// | ||
| /// A new `SchemaFieldMetadata` containing only the intersected metadata | ||
| pub fn intersect_for_union<'a>( |
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give this operates on metadata, I think we should have metadata in the name
| merged.retain(|k, v| input.get(k) == Some(&*v)); | ||
| } | ||
| merged | ||
| intersect_for_union(inputs) |
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since this function just calls another one, I think we could remove this one and call the other
| } | ||
| } | ||
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| /// The metadata used in [`Field::metadata`]. |
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As we move to working with more field metadata, maybe should move this function into its own module -- datafusion/expr/src/metadata.rs or something 🤔
As a follow on PR
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Thanks for the updates @alamb |
3 participants
Which issue does this PR close?
Part of #12736
Rationale for this change
Demonstrate handling of union schema and metadata.
What changes are included in this PR?
Docs and very minor refactoring.
Are these changes tested?
N/A
Are there any user-facing changes?
New docs.