Fix column projection predicate evaluation

[kevinjqliu]

Rationale for this change

Closes#2028
Heavily inspired by #2029 (thanks @Erigara)

This PR fixes a bug where predicate evaluation for a column that is not in the parquet file schema will return no result. This is due to _ColumnNameTranslator visitor returning AlwaysFalse when the column cannot be found in the file schema.

This PR follows the change in #1644 to evaluate predicates based on a field's initial_default. When the evaluated field does not have initial_default, _ColumnNameTranslator will now return AlwaysTrue to scan the entire parquet file and pass the result along for further evaluation.

Are these changes tested?

Yes, added some unit tests for _ColumnNameTranslator/translate_column_names
Added a test for predicate evaluation for projected columns.

Are there any user-facing changes?

[kevinjqliu]

cc @gabeiglio since you implemented #1443 :) could you also take a look?

[Copilot]

Pull Request Overview

This PR fixes a bug in predicate evaluation for column projection where predicates on columns not present in the Parquet file schema would incorrectly return no results. The fix changes the behavior to return AlwaysTrue when a field has no initial_default, allowing for proper row-level filtering.

Key changes:

• Modified _ColumnNameTranslator to return AlwaysTrue instead of AlwaysFalse for missing fields without initial_default
• Added comprehensive unit tests for the translate_column_names function
• Added integration tests for partition value projection with predicates

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
pyiceberg/expressions/visitors.py	Updated _ColumnNameTranslator to handle missing fields without initial_default by returning AlwaysTrue
tests/expressions/test_visitors.py	Added comprehensive unit tests for translate_column_names function covering various scenarios
tests/io/test_pyarrow.py	Added integration tests for partition value projection with predicates

Comments suppressed due to low confidence (1)

tests/expressions/test_visitors.py:1684

• The test creates a field with initial_default="default" but never tests the behavior when this field is missing from the file schema. Consider adding a test case to verify that fields with string defaults are handled correctly.

 NestedField(field_id=1, name="existing_col", field_type=StringType(), required=False, initial_default="default"),

[kevinjqliu]

this isnt right. we should evaluate the column projection predicates

[kevinjqliu]

Closing in favor of #2029