smaheshwar-pltr commented on code in PR #3220:
URL: https://github.com/apache/iceberg-python/pull/3220#discussion_r3106479013
##########
pyiceberg/schema.py:
##########
@@ -1380,6 +1380,58 @@ def primitive(self, primitive: PrimitiveType) ->
PrimitiveType:
return primitive
+class _SetFreshIDsForReplace(_SetFreshIDs):
+ """Assign fresh IDs for a replace operation, reusing IDs from the base
schema by field name.
+
+ For each field in the new schema, if a field with the same full name
exists in the
+ base schema, its ID is reused; otherwise a fresh ID is allocated starting
from
+ last_column_id + 1.
+ """
+
+ def __init__(self, old_id_to_base_id: dict[int, int], starting_id: int) ->
None:
+ self.old_id_to_new_id: dict[int, int] = {}
+ self._old_id_to_base_id = old_id_to_base_id
+ counter = itertools.count(starting_id + 1)
+ self.next_id_func = lambda: next(counter)
+
+ def _get_and_increment(self, current_id: int) -> int:
+ if current_id in self._old_id_to_base_id:
+ new_id = self._old_id_to_base_id[current_id]
+ else:
+ new_id = self.next_id_func()
+ self.old_id_to_new_id[current_id] = new_id
+ return new_id
+
+
+def assign_fresh_schema_ids_for_replace(schema: Schema, base_schema: Schema,
last_column_id: int) -> tuple[Schema, int]:
+ """Assign fresh IDs to a schema for a replace operation, reusing IDs from
the base schema.
+
+ For each field in the new schema, if a field with the same full path name
exists
+ in the base schema, its ID is reused. New fields get IDs starting from
+ last_column_id + 1.
+
+ Args:
+ schema: The new schema to assign IDs to.
+ base_schema: The existing table's current schema (IDs are reused from
here by name).
+ last_column_id: The current table's last_column_id (new IDs start
above this).
+
+ Returns:
+ A tuple of (fresh_schema, new_last_column_id).
+ """
+ base_name_to_id = index_by_name(base_schema)
+ new_id_to_name = index_name_by_id(schema)
Review Comment:
https://github.com/apache/iceberg-python/pull/433#discussion_r1524529502 was
brought up on whether we can reuse previous schemas, but for now I've matched
the Java implementation for simplicity. I figure we can do this improvement as
a follow-up and that it's worth sticking with the reference implementation for
the initial implementation
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