Encapsulate metadata for literals on to a FieldMetadata structure
#16317
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FieldMetadata structure
This was referenced Jun 7, 2025
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I also found we can further unify the metadata handling for Expr::Alias as well, but would like to propose doing that as a follow on PR: |
alamb
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Jun 7, 2025
| /// A constant value along with associated metadata | ||
| Literal(ScalarValue, Option<BTreeMap<String, String>>), | ||
| /// A constant value along with associated [`FieldMetadata`]. | ||
| Literal(ScalarValue, Option<FieldMetadata>), |
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The point of this PR is to put all metadata handling in a Struct to make it easier to work with (and more efficient)
| metadata | ||
| .map(|m| m.into_iter().collect::<HashMap<String, String>>()), | ||
| ))) | ||
| Ok(Transformed::yes(lit_with_metadata(utf8_val, metadata))) |
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this is a pretty good example of the kind of simplification this PR allows (don't have to translate back/forth between HashMap / BTreeMap in various places)
| false => Some(new_metadata), | ||
| }; | ||
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| let metadata = metadata.as_ref().map(|m| FieldMetadata::from(m.clone())); |
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I remove this clone in a follow on PR:
timsaucer
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Jun 7, 2025
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Here is a follow on PR to also use the same structure in |
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Which issue does this PR close?
Related to Support metadata on literal values #15797
Follow on to feat: add metadata to literal expressions #16170
This is an updated version of Encapsulate FieldMetadata timsaucer/datafusion#2
Rationale for this change
As discussed on #16170 (comment), we made an initial PR to add metadata to Expr::Literal as part of DataFusion 48, but the API could use a bit of fine tuning to:
What changes are included in this PR?
FieldMetadataArcto make it fast to cloneAre these changes tested?
Are there any user-facing changes?