Delete the Serialized Dag and DagCode before DagVersion migration

This is necessary for a smooth migration from the old DB to the new
one that added versioning; otherwise, the non-nullable columns raise an integrity error.

Instead of populating those not nullable columns, this seems to be
a better option since the Serialized Dag and DagCode would be regenerated after the migration.

airflow/migrations/versions/0047_3_0_0_add_dag_versioning.py

@@ -44,8 +44,15 @@
 airflow_version = "3.0.0"
 
 
+def _delete_serdag_and_code():
+    op.execute(sa.text("DELETE FROM serialized_dag"))
+    op.execute(sa.text("DELETE FROM dag_code"))
+
+
 def upgrade():
     """Apply add dag versioning."""
+    # Before creating the dag_version table, we need to delete the existing serialized_dag and dag_code tables
+    _delete_serdag_and_code()
     op.create_table(
         "dag_version",
         sa.Column("id", UUIDType(binary=False), nullable=False),

docs/apache-airflow/img/airflow_erd.sha256

@@ -1 +1 @@
-f997746cdee45147831f81bcd2d43ec3ca45d7429afa691e385104987ed51d88
+4adae6a26c3378a5da5468eecfcbd27948c2af285a8dcf12ff8c3969e19f19f7