GH-48024: [C++][Python] Preserve schema metadata in RenameColumns #48669
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Both `Table::RenameColumns()` and `RecordBatch::RenameColumns()` were dropping schema metadata when creating the renamed table/batch. This also affected `Schema::WithNames()` which had the same issue. The fix passes `schema()->metadata()` when constructing the new schema, following the same pattern used by `SelectColumns()` and `Flatten()`. Changes: - Fix `Table::RenameColumns()` in table.cc - Fix `RecordBatch::RenameColumns()` in record_batch.cc - Fix `Schema::WithNames()` in type.cc - Add C++ tests for all three fixes - Add Python test for Table and RecordBatch
yashwantbezawada
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raulcd and
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Component: C++
Component: Python
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Rationale for this change
Table.rename_columns()was dropping schema metadata, which is unexpected behavior. When you rename columns, you'd expect everything else about the schema to stay the same - including any metadata attached to it.I noticed
RecordBatch.rename_columns()andSchema.WithNames()had the same problem, so I fixed those too.What changes are included in this PR?
The issue was that these methods were calling
::arrow::schema(fields)without passing along the original metadata. The fix just addsschema()->metadata()as the second argument, same pattern thatSelectColumns()andFlatten()already use.Files changed:
cpp/src/arrow/table.cc- fix for Table::RenameColumnscpp/src/arrow/record_batch.cc- fix for RecordBatch::RenameColumnscpp/src/arrow/type.cc- fix for Schema::WithNamesAre these changes tested?
Yes, added tests for each fix:
table_test.ccrecord_batch_test.cctype_test.cctest_table.py(covers both Table and RecordBatch)Are there any user-facing changes?
Yes, this is a bug fix. After this change,
rename_columns()will preserve schema metadata instead of dropping it.