Refactor SerializedDagModel and DagCode for dag versioning

Now that we have dag versioning, the SerializedDagModel and
DagCode objects should no longer be deleted. Deletion should
start with the DagModel, which will cascade to the DagVersion,
then to the DagCode and SerializedDagModel.

Also, these models are no longer updated. Instead, a new
object is added; hence, the last_updated is changed to created_at.

airflow/api/common/delete_dag.py

@@ -28,7 +28,6 @@
 from airflow.exceptions import AirflowException, DagNotFound
 from airflow.models import DagModel
 from airflow.models.errors import ParseImportError
-from airflow.models.serialized_dag import SerializedDagModel
 from airflow.utils.db import get_sqla_model_classes
 from airflow.utils.session import NEW_SESSION, provide_session
 from airflow.utils.state import TaskInstanceState
@@ -64,11 +63,6 @@ def delete_dag(dag_id: str, keep_records_in_log: bool = True, session: Session =
     if dag is None:
         raise DagNotFound(f"Dag id {dag_id} not found")
 
-    # Scheduler removes DAGs without files from serialized_dag table every dag_dir_list_interval.
-    # There may be a lag, so explicitly removes serialized DAG here.
-    if SerializedDagModel.has_dag(dag_id=dag_id, session=session):
-        SerializedDagModel.remove_dag(dag_id=dag_id, session=session)
-
     count = 0
 
     for model in get_sqla_model_classes():

airflow/api_internal/endpoints/rpc_api_endpoint.py

@@ -138,7 +138,6 @@ def initialize_method_map() -> dict[str, Callable]:
         DagRun._get_log_template,
         RenderedTaskInstanceFields._update_runtime_evaluated_template_fields,
         SerializedDagModel.get_serialized_dag,
-        SerializedDagModel.remove_deleted_dags,
         SkipMixin._skip,
         SkipMixin._skip_all_except,
         TaskInstance._check_and_change_state_before_execution,

airflow/dag_processing/manager.py

@@ -506,7 +506,7 @@ def deactivate_stale_dags(
         """
         Detect DAGs which are no longer present in files.
 
-        Deactivate them and remove them in the serialized_dag table.
+        Deactivate them.
         """
         to_deactivate = set()
         query = select(DagModel.dag_id, DagModel.fileloc, DagModel.last_parsed_time).where(DagModel.is_active)

airflow/migrations/versions/0047_3_0_0_add_dag_versioning.py

@@ -81,6 +81,8 @@ def upgrade():
             ondelete="CASCADE",
         )
         batch_op.create_unique_constraint("dag_code_dag_version_id_uq", ["dag_version_id"])
+        batch_op.drop_column("last_updated")
+        batch_op.add_column(sa.Column("created_at", UtcDateTime(), nullable=False, default=timezone.utcnow))
 
     with op.batch_alter_table(
         "serialized_dag", recreate="always", naming_convention=naming_convention
@@ -100,6 +102,8 @@ def upgrade():
             ondelete="CASCADE",
         )
         batch_op.create_unique_constraint("serialized_dag_dag_version_id_uq", ["dag_version_id"])
+        batch_op.drop_column("last_updated")
+        batch_op.add_column(sa.Column("created_at", UtcDateTime(), nullable=False, default=timezone.utcnow))
 
     with op.batch_alter_table("task_instance", schema=None) as batch_op:
         batch_op.add_column(sa.Column("dag_version_id", UUIDType(binary=False)))

airflow/models/dag_version.py

@@ -62,7 +62,7 @@ class DagVersion(Base):
     )
     dag_runs = relationship("DagRun", back_populates="dag_version", cascade="all, delete, delete-orphan")
     task_instances = relationship("TaskInstance", back_populates="dag_version")
-    created_at = Column(UtcDateTime, default=timezone.utcnow)
+    created_at = Column(UtcDateTime, nullable=False, default=timezone.utcnow)
 
     __table_args__ = (
         UniqueConstraint("dag_id", "version_number", name="dag_id_v_name_v_number_unique_constraint"),

airflow/models/dagcode.py

@@ -18,16 +18,15 @@
 
 import logging
 import struct
-from typing import TYPE_CHECKING, Collection
+from typing import TYPE_CHECKING
 
 import uuid6
-from sqlalchemy import BigInteger, Column, ForeignKey, String, Text, delete, select
+from sqlalchemy import BigInteger, Column, ForeignKey, String, Text, select
 from sqlalchemy.dialects.mysql import MEDIUMTEXT
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql.expression import literal
 from sqlalchemy_utils import UUIDType
 
-from airflow.api_internal.internal_api_call import internal_api_call
 from airflow.configuration import conf
 from airflow.exceptions import DagCodeNotFound
 from airflow.models.base import Base
@@ -58,7 +57,7 @@ class DagCode(Base):
     fileloc_hash = Column(BigInteger, nullable=False)
     fileloc = Column(String(2000), nullable=False)
     # The max length of fileloc exceeds the limit of indexing.
-    last_updated = Column(UtcDateTime, nullable=False)
+    created_at = Column(UtcDateTime, nullable=False, default=timezone.utcnow)
     source_code = Column(Text().with_variant(MEDIUMTEXT(), "mysql"), nullable=False)
     dag_version_id = Column(
         UUIDType(binary=False), ForeignKey("dag_version.id", ondelete="CASCADE"), nullable=False, unique=True
@@ -74,7 +73,7 @@ def __init__(self, dag_version, full_filepath: str, source_code: str | None = No
 
     @classmethod
     @provide_session
-    def write_dag(cls, dag_version: DagVersion, fileloc: str, session: Session = NEW_SESSION) -> DagCode:
+    def write_code(cls, dag_version: DagVersion, fileloc: str, session: Session = NEW_SESSION) -> DagCode:
         """
         Write code into database.
 
@@ -87,36 +86,6 @@ def write_dag(cls, dag_version: DagVersion, fileloc: str, session: Session = NEW
         log.debug("DAG file %s written into DagCode table", fileloc)
         return dag_code
 
-    @classmethod
-    @internal_api_call
-    @provide_session
-    def remove_deleted_code(
-        cls,
-        alive_dag_filelocs: Collection[str],
-        processor_subdir: str,
-        session: Session = NEW_SESSION,
-    ) -> None:
-        """
-        Delete code not included in alive_dag_filelocs.
-
-        :param alive_dag_filelocs: file paths of alive DAGs
-        :param processor_subdir: dag processor subdir
-        :param session: ORM Session
-        """
-        alive_fileloc_hashes = [cls.dag_fileloc_hash(fileloc) for fileloc in alive_dag_filelocs]
-
-        log.debug("Deleting code from %s table ", cls.__tablename__)
-
-        session.execute(
-            delete(cls)
-            .where(
-                cls.fileloc_hash.notin_(alive_fileloc_hashes),
-                cls.fileloc.notin_(alive_dag_filelocs),
-                cls.fileloc.contains(processor_subdir),
-            )
-            .execution_options(synchronize_session="fetch")
-        )
-
     @classmethod
     @provide_session
     def has_dag(cls, fileloc: str, session: Session = NEW_SESSION) -> bool:
@@ -172,7 +141,7 @@ def _get_code_from_db(cls, fileloc, session: Session = NEW_SESSION) -> str:
         dag_code = session.scalar(
             select(cls)
             .where(cls.fileloc_hash == cls.dag_fileloc_hash(fileloc))
-            .order_by(cls.last_updated.desc())
+            .order_by(cls.created_at.desc())
             .limit(1)
         )
         if not dag_code:

airflow/models/serialized_dag.py

@@ -22,11 +22,11 @@
 import logging
 import zlib
 from datetime import timedelta
-from typing import TYPE_CHECKING, Any, Collection
+from typing import TYPE_CHECKING, Any
 
 import sqlalchemy_jsonfield
 import uuid6
-from sqlalchemy import Column, ForeignKey, LargeBinary, String, exc, or_, select
+from sqlalchemy import Column, ForeignKey, LargeBinary, String, exc, select
 from sqlalchemy.orm import backref, foreign, relationship
 from sqlalchemy.sql.expression import func, literal
 from sqlalchemy_utils import UUIDType
@@ -83,7 +83,7 @@ class SerializedDagModel(Base):
     dag_id = Column(String(ID_LEN), nullable=False)
     _data = Column("data", sqlalchemy_jsonfield.JSONField(json=json), nullable=True)
     _data_compressed = Column("data_compressed", LargeBinary, nullable=True)
-    last_updated = Column(UtcDateTime, nullable=False)
+    created_at = Column(UtcDateTime, nullable=False, default=timezone.utcnow)
     dag_hash = Column(String(32), nullable=False)
     processor_subdir = Column(String(2000), nullable=True)
 
@@ -110,7 +110,6 @@ class SerializedDagModel(Base):
 
     def __init__(self, dag: DAG, processor_subdir: str | None = None) -> None:
         self.dag_id = dag.dag_id
-        self.last_updated = timezone.utcnow()
         self.processor_subdir = processor_subdir
 
         dag_data = SerializedDAG.to_dict(dag)
@@ -186,7 +185,7 @@ def write_dag(
             if session.scalar(
                 select(literal(True)).where(
                     cls.dag_id == dag.dag_id,
-                    (timezone.utcnow() - timedelta(seconds=min_update_interval)) < cls.last_updated,
+                    (timezone.utcnow() - timedelta(seconds=min_update_interval)) < cls.created_at,
                 )
             ):
                 return False
@@ -196,7 +195,7 @@ def write_dag(
         serialized_dag_db = session.execute(
             select(cls.dag_hash, cls.processor_subdir)
             .where(cls.dag_id == dag.dag_id)
-            .order_by(cls.last_updated.desc())
+            .order_by(cls.created_at.desc())
         ).first()
 
         if (
@@ -215,13 +214,12 @@ def write_dag(
         new_serialized_dag.dag_version = dagv
         session.add(new_serialized_dag)
         log.debug("DAG: %s written to the DB", dag.dag_id)
-
-        DagCode.write_dag(dagv, dag.fileloc, session=session)
+        DagCode.write_code(dagv, dag.fileloc, session=session)
         return True
 
     @classmethod
     def latest_item_select_object(cls, dag_id):
-        return select(cls).where(cls.dag_id == dag_id).order_by(cls.last_updated.desc()).limit(1)
+        return select(cls).where(cls.dag_id == dag_id).order_by(cls.created_at.desc()).limit(1)
 
     @classmethod
     @provide_session
@@ -237,7 +235,7 @@ def get_latest_serialized_dags(
         """
         # Subquery to get the latest serdag per dag_id
         latest_serdag_subquery = (
-            session.query(cls.dag_id, func.max(cls.last_updated).label("last_updated"))
+            session.query(cls.dag_id, func.max(cls.created_at).label("created_at"))
             .filter(cls.dag_id.in_(dag_ids))
             .group_by(cls.dag_id)
             .subquery()
@@ -246,7 +244,7 @@ def get_latest_serialized_dags(
             select(cls)
             .join(
                 latest_serdag_subquery,
-                cls.last_updated == latest_serdag_subquery.c.last_updated,
+                cls.created_at == latest_serdag_subquery.c.created_at,
             )
             .where(cls.dag_id.in_(dag_ids))
         ).all()
@@ -262,15 +260,15 @@ def read_all_dags(cls, session: Session = NEW_SESSION) -> dict[str, SerializedDA
         :returns: a dict of DAGs read from database
         """
         latest_serialized_dag_subquery = (
-            session.query(cls.dag_id, func.max(cls.last_updated).label("max_updated"))
+            session.query(cls.dag_id, func.max(cls.created_at).label("max_created"))
             .group_by(cls.dag_id)
             .subquery()
         )
         serialized_dags = session.scalars(
             select(cls).join(
                 latest_serialized_dag_subquery,
                 (cls.dag_id == latest_serialized_dag_subquery.c.dag_id)
-                and (cls.last_updated == latest_serialized_dag_subquery.c.max_updated),
+                and (cls.created_at == latest_serialized_dag_subquery.c.max_created),
             )
         )
 
@@ -313,47 +311,6 @@ def dag(self) -> SerializedDAG:
             raise ValueError("invalid or missing serialized DAG data")
         return SerializedDAG.from_dict(data)
 
-    @classmethod
-    @provide_session
-    def remove_dag(cls, dag_id: str, session: Session = NEW_SESSION) -> None:
-        """
-        Delete a DAG with given dag_id.
-
-        :param dag_id: dag_id to be deleted
-        :param session: ORM Session.
-        """
-        session.execute(cls.__table__.delete().where(cls.dag_id == dag_id))
-
-    @classmethod
-    @internal_api_call
-    @provide_session
-    def remove_deleted_dags(
-        cls,
-        alive_dag_filelocs: Collection[str],
-        processor_subdir: str | None = None,
-        session: Session = NEW_SESSION,
-    ) -> None:
-        """
-        Delete DAGs not included in alive_dag_filelocs.
-
-        :param alive_dag_filelocs: file paths of alive DAGs
-        :param processor_subdir: dag processor subdir
-        :param session: ORM Session
-        """
-        log.debug(
-            "Deleting Serialized DAGs (for which DAG files are deleted) from %s table ", cls.__tablename__
-        )
-        # Deleting the DagModel cascade deletes the serialized Dag through the dag version relationship
-        session.execute(
-            DagModel.__table__.delete().where(
-                DagModel.fileloc.notin_(alive_dag_filelocs),
-                or_(
-                    DagModel.processor_subdir.is_(None),
-                    DagModel.processor_subdir == processor_subdir,
-                ),
-            )
-        )
-
     @classmethod
     @provide_session
     def has_dag(cls, dag_id: str, session: Session = NEW_SESSION) -> bool:
@@ -418,7 +375,7 @@ def get_last_updated_datetime(cls, dag_id: str, session: Session = NEW_SESSION)
         :param session: ORM Session
         """
         return session.scalar(
-            select(cls.last_updated).where(cls.dag_id == dag_id).order_by(cls.last_updated.desc()).limit(1)
+            select(cls.created_at).where(cls.dag_id == dag_id).order_by(cls.created_at.desc()).limit(1)
         )
 
     @classmethod
@@ -429,7 +386,7 @@ def get_max_last_updated_datetime(cls, session: Session = NEW_SESSION) -> dateti
 
         :param session: ORM Session
         """
-        return session.scalar(select(func.max(cls.last_updated)))
+        return session.scalar(select(func.max(cls.created_at)))
 
     @classmethod
     @provide_session
@@ -442,7 +399,7 @@ def get_latest_version_hash(cls, dag_id: str, session: Session = NEW_SESSION) ->
         :return: DAG Hash, or None if the DAG is not found
         """
         return session.scalar(
-            select(cls.dag_hash).where(cls.dag_id == dag_id).order_by(cls.last_updated.desc()).limit(1)
+            select(cls.dag_hash).where(cls.dag_id == dag_id).order_by(cls.created_at.desc()).limit(1)
         )
 
     @classmethod
@@ -461,9 +418,9 @@ def get_latest_version_hash_and_updated_datetime(
         :return: A tuple of DAG Hash and last updated datetime, or None if the DAG is not found
         """
         return session.execute(
-            select(cls.dag_hash, cls.last_updated)
+            select(cls.dag_hash, cls.created_at)
             .where(cls.dag_id == dag_id)
-            .order_by(cls.last_updated.desc())
+            .order_by(cls.created_at.desc())
             .limit(1)
         ).one_or_none()
 
@@ -476,7 +433,7 @@ def get_dag_dependencies(cls, session: Session = NEW_SESSION) -> dict[str, list[
         :param session: ORM Session
         """
         latest_sdag_subquery = (
-            session.query(cls.dag_id, func.max(cls.last_updated).label("max_updated"))
+            session.query(cls.dag_id, func.max(cls.created_at).label("max_created"))
             .group_by(cls.dag_id)
             .subquery()
         )
@@ -485,7 +442,7 @@ def get_dag_dependencies(cls, session: Session = NEW_SESSION) -> dict[str, list[
                 select(cls.dag_id, func.json_extract(cls._data, "$.dag.dag_dependencies")).join(
                     latest_sdag_subquery,
                     (cls.dag_id == latest_sdag_subquery.c.dag_id)
-                    and (cls.last_updated == latest_sdag_subquery.c.max_updated),
+                    and (cls.created_at == latest_sdag_subquery.c.max_created),
                 )
             )
             iterator = ((dag_id, json.loads(deps_data) if deps_data else []) for dag_id, deps_data in query)
@@ -494,7 +451,7 @@ def get_dag_dependencies(cls, session: Session = NEW_SESSION) -> dict[str, list[
                 select(cls.dag_id, func.json_extract_path(cls._data, "dag", "dag_dependencies")).join(
                     latest_sdag_subquery,
                     (cls.dag_id == latest_sdag_subquery.c.dag_id)
-                    and (cls.last_updated == latest_sdag_subquery.c.max_updated),
+                    and (cls.created_at == latest_sdag_subquery.c.max_created),
                 )
             )
         return {dag_id: [DagDependency(**d) for d in (deps_data or [])] for dag_id, deps_data in iterator}

docs/apache-airflow/img/airflow_erd.sha256

@@ -1 +1 @@
-2f5a0c99e82990e669d975bf366dc82202c5d460063aaebff3e10abd2acc15f9
+49c3285d6abc128193c2255882a104bde24a9014d90693ecc83a908ea5d61e5d