ashb commented on code in PR #24044:
URL: https://github.com/apache/airflow/pull/24044#discussion_r906032357
##########
airflow/utils/db.py:
##########
@@ -1675,6 +1675,56 @@ def create_global_lock(
pass
+def compare_type(context, inspected_column, metadata_column, inspected_type,
metadata_type):
+ """
+ Compare types between ORM and DB .
+
+ return False if the metadata_type is the same as the inspected_type
+ or None to allow the default implementation to compare these
+ types. a return value of True means the two types do not
+ match and should result in a type change operation.
+ """
+ if context.dialect.name == 'mysql':
+ from sqlalchemy import String
+ from sqlalchemy.dialects import mysql
+
+ if isinstance(inspected_type, mysql.VARCHAR) and
isinstance(metadata_type, String):
+ # This is a hack to get around MySQL VARCHAR collation
+ # not being possible to change from utf8_bin to utf8mb3_bin
+ return False
+ return None
+
+
+def compare_server_default(
+ context, inspected_column, metadata_column, inspected_default,
metadata_default, rendered_metadata_default
+):
+ """
+ Compare server defaults between ORM and DB .
+
+ return True if the defaults are different, False if not, or None to allow
the default implementation
+ to compare these defaults
+
+ Comparing server_default is not accurate in MSSQL because the
+ inspected_default above != metadata_default, while in Postgres/MySQL they
are equal.
+ This is an issue with alembic
+ In SQLite: task_instance.map_index & task_reschedule.map_index
+ are not comparing accurately. Sometimes they are equal, sometimes they are
not.
+ Alembic warned that this feature has varied accuracy depending on backends.
+ See:
(https://alembic.sqlalchemy.org/en/latest/api/runtime.html#alembic.runtime.
+ environment.EnvironmentContext.configure.params.compare_server_default)
+ """
+ dialect_name = context.connection.dialect.name
+ if dialect_name in ['mssql', 'sqlite']:
+ return False
+ if (
+ dialect_name == 'mysql'
+ and metadata_column.name == 'pool_slots'
+ and metadata_column.table.name == 'task_instance'
+ ):
+ return False
Review Comment:
We should explain why we are doing this as it's not mentioned anywhere in
the code
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: commits-unsubscr...@airflow.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
