HonahX commented on code in PR #139:
URL: https://github.com/apache/iceberg-python/pull/139#discussion_r1401641335
##########
pyiceberg/table/__init__.py:
##########
@@ -350,6 +357,241 @@ class RemovePropertiesUpdate(TableUpdate):
removals: List[str]
+class TableMetadataUpdateContext:
+ updates: List[TableUpdate]
+ last_added_schema_id: Optional[int]
+
+ def __init__(self) -> None:
+ self.updates = []
+ self.last_added_schema_id = None
+
+ def is_added_snapshot(self, snapshot_id: int) -> bool:
+ return any(
+ update.snapshot.snapshot_id == snapshot_id
+ for update in self.updates
+ if update.action == TableUpdateAction.add_snapshot
+ )
+
+ def is_added_schema(self, schema_id: int) -> bool:
+ return any(
+ update.schema_.schema_id == schema_id for update in self.updates
if update.action == TableUpdateAction.add_schema
+ )
+
+
+@singledispatch
+def apply_table_update(update: TableUpdate, base_metadata: TableMetadata,
context: TableMetadataUpdateContext) -> TableMetadata:
+ """Apply a table update to the table metadata.
+
+ Args:
+ update: The update to be applied.
+ base_metadata: The base metadata to be updated.
+ context: Contains previous updates, last_added_snapshot_id and other
change tracking information in the current transaction.
+
+ Returns:
+ The updated metadata.
+
+ """
+ raise NotImplementedError(f"Unsupported table update: {update}")
+
+
+@apply_table_update.register(UpgradeFormatVersionUpdate)
+def _(update: UpgradeFormatVersionUpdate, base_metadata: TableMetadata,
context: TableMetadataUpdateContext) -> TableMetadata:
+ if update.format_version > SUPPORTED_TABLE_FORMAT_VERSION:
+ raise ValueError(f"Unsupported table format version:
{update.format_version}")
+
+ if update.format_version < base_metadata.format_version:
+ raise ValueError(f"Cannot downgrade v{base_metadata.format_version}
table to v{update.format_version}")
+
+ if update.format_version == base_metadata.format_version:
+ return base_metadata
+
+ updated_metadata_data = copy(base_metadata.model_dump())
+ updated_metadata_data["format-version"] = update.format_version
+
+ context.updates.append(update)
+ return TableMetadataUtil.parse_obj(updated_metadata_data)
+
+
+@apply_table_update.register(AddSchemaUpdate)
+def _(update: AddSchemaUpdate, base_metadata: TableMetadata, context:
TableMetadataUpdateContext) -> TableMetadata:
+ def reuse_or_create_new_schema_id(new_schema: Schema) -> Tuple[int, bool]:
+ """Reuse schema id if schema already exists, otherwise create a new
one.
+
+ Args:
+ new_schema: The new schema to be added.
+
+ Returns:
+ The new schema id and whether the schema already exists.
+ """
+ result_schema_id = base_metadata.current_schema_id
+ for schema in base_metadata.schemas:
+ if schema == new_schema:
+ return schema.schema_id, True
+ elif schema.schema_id >= result_schema_id:
+ result_schema_id = schema.schema_id + 1
+ return result_schema_id, False
+
+ if update.last_column_id < base_metadata.last_column_id:
+ raise ValueError(f"Invalid last column id {update.last_column_id},
must be >= {base_metadata.last_column_id}")
+
+ new_schema_id, schema_found = reuse_or_create_new_schema_id(update.schema_)
+ if schema_found and update.last_column_id == base_metadata.last_column_id:
+ if context.last_added_schema_id is not None and
context.is_added_schema(new_schema_id):
+ context.last_added_schema_id = new_schema_id
+ return base_metadata
+
+ updated_metadata_data = copy(base_metadata.model_dump())
+ updated_metadata_data["last-column-id"] = update.last_column_id
+
+ new_schema = (
+ update.schema_
+ if new_schema_id == update.schema_.schema_id
+ else Schema(*update.schema_.fields, schema_id=new_schema_id,
identifier_field_ids=update.schema_.identifier_field_ids)
+ )
Review Comment:
Thanks for the explanation! Just to confirm my understanding, in pyiceberg,
one transaction should only have one `AddSchemaUpdate` because all updates
related to the schema should be accumulated via `UpdateSchema`. Also, the
`AddSchemaUpdate` should only come from `UpdateSchema`. Hence, we can trust the
`schema_id` in the update and do not need the logic to handle multiple schema
added in one transaction.
related discussion:
https://github.com/apache/iceberg/pull/6323#discussion_r1217020366.
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