fix: reject DecimalType with precision outside [1, 38]#3584
Open
gitcommit90 wants to merge 2 commits into
Open
fix: reject DecimalType with precision outside [1, 38]#3584gitcommit90 wants to merge 2 commits into
gitcommit90 wants to merge 2 commits into
Conversation
The Iceberg spec states precision must be 38 or less [1]. The Python implementation silently accepted any precision, including values like decimal(39, 0) that cannot be represented in decimal fixed-byte storage. This aligns the Python library with the Java reference implementation which raises IllegalArgumentException for precision > 38. Changes: - Add a validation check in DecimalType.__init__ that raises ValidationError when precision < 1 or precision > 38 - Add four tests covering: precision=39 (direct), precision=0 (direct), precision=38 (boundary, must pass), and precision=39 via deserialization Fixes apache#3583 [1] https://iceberg.apache.org/spec/#primitive-types
ebyhr
reviewed
Jun 29, 2026
|
|
||
| def test_decimal_deserialization_precision_above_38_raises() -> None: | ||
| """Deserialization of decimal(39, 0) must also raise a ValidationError.""" | ||
| with pytest.raises(Exception, match="Precision must be between 1 and 38"): |
Member
There was a problem hiding this comment.
Suggested change
| with pytest.raises(Exception, match="Precision must be between 1 and 38"): | |
| with pytest.raises(ValidationError, match="Precision must be between 1 and 38"): |
|
|
||
| def __init__(self, precision: int, scale: int) -> None: | ||
| if not (1 <= precision <= 38): | ||
| raise ValidationError(f"Precision must be between 1 and 38 (inclusive), got: {precision}") |
Member
There was a problem hiding this comment.
model_copy still misses this guard. The following code doesn't raise the exception:
DecimalType(10, 2).model_copy(update={"root": (39, 0)})Could you consider using @model_validator(mode="after")?
Collaborator
There was a problem hiding this comment.
+1. This is how we do validations elsewhere in the code as well.
Comment on lines
+531
to
+533
| """Precision 0 is not valid; minimum precision is 1.""" | ||
| with pytest.raises(ValidationError, match="Precision must be between 1 and 38"): | ||
| DecimalType(0, 0) |
Member
There was a problem hiding this comment.
nit: We could remove the code comment. It's obvious when reading the code.
This was referenced Jun 30, 2026
rambleraptor
reviewed
Jul 6, 2026
rambleraptor
left a comment
rambleraptor
left a comment
Collaborator
There was a problem hiding this comment.
This is basically there. Thanks for doing that
| options=self.options, | ||
| ).plan_files( | ||
| manifests=manifests, | ||
| manifest_entry_filter=lambda manifest_entry: manifest_entry.snapshot_id in append_snapshot_ids |
Collaborator
There was a problem hiding this comment.
This looks stray. Can you remove this?
|
|
||
| def __init__(self, precision: int, scale: int) -> None: | ||
| if not (1 <= precision <= 38): | ||
| raise ValidationError(f"Precision must be between 1 and 38 (inclusive), got: {precision}") |
Collaborator
There was a problem hiding this comment.
+1. This is how we do validations elsewhere in the code as well.
Collaborator
|
@gitcommit90 are you able to make these quick changes? I'd love to get this in before 0.12 |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The Iceberg spec states precision must be 38 or less (minimum 1). The Python library silently accepted any precision value;
DecimalType(39, 0)succeeded with no error, which can corrupt downstream fixed-byte decimal encoding.The Java reference implementation rejects it:
DecimalType.of(39, 0)raisesIllegalArgumentException.Fix: Add a 2-line guard in
DecimalType.__init__that raisespyiceberg.exceptions.ValidationErrorwhenprecision < 1orprecision > 38. Uses the same exception class and pattern already used throughoutpyiceberg/types.py.Tests added (4 new):
test_decimal_precision_above_38_raises— precision=39 raisestest_decimal_precision_zero_raises— precision=0 raisestest_decimal_precision_boundary_38_accepted— precision=38 acceptedtest_decimal_deserialization_precision_above_38_raises— deserialization path also raisesAll 292 existing tests pass; ruff clean.
closes #3583