[GitHub] [iceberg] rdblue commented on a diff in pull request #5929: Python: Add partition_type to partition_spec

[GitBox <gi...@apache.org>]

rdblue commented on code in PR #5929:
URL: https://github.com/apache/iceberg/pull/5929#discussion_r989537398


##########
python/tests/table/test_partitioning.py:
##########
@@ -102,3 +109,16 @@ def test_deserialize_partition_spec():
             PartitionField(source_id=2, field_id=1001, transform=BucketTransform(num_buckets=25), name="int_bucket"),
         ),
     )
+
+
+def test_partition_type(table_schema_simple: Schema) -> None:
+    spec = PartitionSpec(
+        PartitionField(source_id=1, field_id=1000, transform=TruncateTransform(width=19), name="str_truncate"),
+        PartitionField(source_id=2, field_id=1001, transform=BucketTransform(num_buckets=25), name="int_bucket"),
+        spec_id=3,
+    )
+
+    assert spec.partition_type(table_schema_simple) == StructType(
+        NestedField(field_id=1000, name="str_truncate", field_type=StringType(), required=True),
+        NestedField(field_id=1001, name="int_bucket", field_type=IntegerType(), required=True),

Review Comment:
   The partition fields should be optional.
   
   * All partition transforms are required to produce `null` if the input value is `null`, so it can happen when the source column is optional
   * Partition fields may be added later, in which case not all files would have the result field and it may be `null`
   
   There is a case where we can guarantee that a partition field in the first and only partition spec that uses a required source column will never be null, but it doesn't seem worth tracking this case.



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