[SPARK-47681][FOLLOWUP] Fix schema_of_variant for float inputs. #47058
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@cloud-fan could you help review? Thanks! |
cloud-fan
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Jun 21, 2024
| @@ -372,6 +372,11 @@ object JsonInferSchema { | |||
| case (DoubleType, _: DecimalType) | (_: DecimalType, DoubleType) => | |||
| DoubleType | |||
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| // This branch is only used by `SchemaOfVariant.mergeSchema` because `JsonInferSchema` never | |||
| // produces `FloatType`. | |||
| case (FloatType, _: DecimalType) | (_: DecimalType, FloatType) => | |||
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Is there a standard for this? These two are not compatible, because float is approximate but decimal is not.
Anyway, I'm fine with this as we already did it for double type.
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I'm not aware of an existing standard, but I think we can follow the type resolution rules in the add operator:
Based on this result, I think it may be better to change the result of float x decimal into double.
Changing decimal into float/double may indeed lose precision, but I think it is a reasonable approach in the shcema inference.
cloud-fan
approved these changes
Jun 21, 2024
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@cloud-fan could you help merge it? Thanks! |
cloud-fan
approved these changes
Jun 24, 2024
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thanks, merging to master! |
attilapiros
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Oct 4, 2024
### What changes were proposed in this pull request? The current `schema_of_variant` depends on `JsonInferSchema.compatibleType` to find the common type of two types. This function doesn't handle the case of `float x decimal` or `decimal x float` correctly. It doesn't produce the expected result, but consider the two types as incompatible and produces `variant`. This change doesn't affect the JSON schema inference because it never produces `float` beforehand. ### Why are the changes needed? It is a bug fix and is required to process floats correctly. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? A new unit test that checks all type combinations. ### Was this patch authored or co-authored using generative AI tooling? No. Closes apache#47058 from chenhao-db/fix_schema_of_variant_float. Authored-by: Chenhao Li <chenhao.li@databricks.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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What changes were proposed in this pull request?
The current
schema_of_variantdepends onJsonInferSchema.compatibleTypeto find the common type of two types. This function doesn't handle the case offloat x decimalordecimal x floatcorrectly. It doesn't produce the expected result, but consider the two types as incompatible and producesvariant. This change doesn't affect the JSON schema inference because it never producesfloatbeforehand.Why are the changes needed?
It is a bug fix and is required to process floats correctly.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
A new unit test that checks all type combinations.
Was this patch authored or co-authored using generative AI tooling?
No.