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@jeroko jeroko commented Oct 27, 2025

Rationale for this change

Closes #2131

The PR relaxes the constraint that prevented adding any file with field IDs, and replaces it with a constraint that prevents adding files which contain field IDs that are inconsistent with the field IDs of the table. If the field IDs are compatible, then they can be added safely, if not, they will be rejected.

Are these changes tested?

Yes

Are there any user-facing changes?

Yes

@jeroko jeroko force-pushed the remove-field_id-constraint-on-add_files branch 2 times, most recently from 0b599c6 to d580102 Compare October 27, 2025 14:00
@jeroko jeroko force-pushed the remove-field_id-constraint-on-add_files branch from d580102 to 1addf60 Compare October 27, 2025 14:31
@jeroko jeroko marked this pull request as ready for review October 27, 2025 14:57
Comment on lines 2637 to 2638
requested_id_to_name = requested_schema._lazy_id_to_name
provided_id_to_name = provided_schema._lazy_id_to_name
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Hey @jeroko Thanks for working on this, and adding this check.

However, I don't think we really care about the names; it is not a problem when they differ. However, if you add a file with a different schema, we can brick the table because of issues in the types. Should we check if the file contains the expected type for each of the IDs instead?

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@jeroko jeroko Oct 27, 2025

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@Fokko Right, we should not care about the names if the IDs are provided, and the mapping between the IDs and the types was already checked in the call to _check_schema_compatible at the end of this function. In that case I didn't really need to add any extra check, just a new test to verify that files with matching field IDs and incompatible types fail.

@jeroko jeroko requested a review from Fokko October 29, 2025 08:19
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Thanks for the PR! This is a great addition. Added a few comments

Comment on lines 2644 to 2647
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i think we should at least check that the parquet field IDs align with the Iceberg field IDs

`add_files` can work with Parquet files both with and without field IDs in their metadata:
- **Files with field IDs**: When field IDs are present in the Parquet metadata, they must match the corresponding field IDs in the Iceberg table schema. This is common for files generated by tools like Spark or when using or other libraries with explicit field ID metadata.
- **Files without field IDs**: When field IDs are absent, the table must have a [Name Mapping](https://iceberg.apache.org/spec/?h=name+mapping#name-mapping-serialization) to map field names to Iceberg field IDs. `add_files` will automatically create a Name Mapping based on the table's current schema if one doesn't already exist.
In both cases, a Name Mapping is created if the table doesn't have one, ensuring compatibility with various readers.
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For parquet files with field ID, i dont think we necessary need the name mapping if its aligned with the table schema field IDs
But we can address this separately

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Add files support for parquet field_ids

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