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new bf3d4022db3 Remove slow-on-MySQL and now needless CHECK CONSTRAINT
(#74409)
bf3d4022db3 is described below
commit bf3d4022db38ef5b5ca4cf0bd175b31be0f3fea9
Author: Ash Berlin-Taylor <[email protected]>
AuthorDate: Thu Oct 8 10:49:54 2026 +0100
Remove slow-on-MySQL and now needless CHECK CONSTRAINT (#74409)
When migration 0136 was written and merged, xcom was still being written to,
but now that 0142 has landed this table is read-only.
So it makes no sense to spend any time writing this migration.
(It turns out that adding a CHECK constraint on mysql _copies the entire
table_. Large values and all.)
---
.../versions/0136_3_4_0_fold_task_map_into_xcom_mapped_length.py | 2 --
airflow-core/src/airflow/models/xcom.py | 2 --
2 files changed, 4 deletions(-)
diff --git
a/airflow-core/src/airflow/migrations/versions/0136_3_4_0_fold_task_map_into_xcom_mapped_length.py
b/airflow-core/src/airflow/migrations/versions/0136_3_4_0_fold_task_map_into_xcom_mapped_length.py
index 86e1e7ccf4a..60e3bea956a 100644
---
a/airflow-core/src/airflow/migrations/versions/0136_3_4_0_fold_task_map_into_xcom_mapped_length.py
+++
b/airflow-core/src/airflow/migrations/versions/0136_3_4_0_fold_task_map_into_xcom_mapped_length.py
@@ -118,7 +118,6 @@ def upgrade():
with disable_sqlite_fkeys(op):
with op.batch_alter_table("xcom", schema=None) as batch_op:
batch_op.add_column(sa.Column("mapped_length", sa.Integer(),
nullable=True))
- batch_op.create_check_constraint("mapped_length_not_negative",
"mapped_length >= 0")
op.execute(build_backfill_statement())
op.drop_table("task_map")
@@ -154,5 +153,4 @@ def downgrade():
op.execute(build_restore_statement())
with op.batch_alter_table("xcom", schema=None) as batch_op:
- batch_op.drop_constraint("mapped_length_not_negative",
type_="check")
batch_op.drop_column("mapped_length")
diff --git a/airflow-core/src/airflow/models/xcom.py
b/airflow-core/src/airflow/models/xcom.py
index e64789cb8ce..2a3ba95ed53 100644
--- a/airflow-core/src/airflow/models/xcom.py
+++ b/airflow-core/src/airflow/models/xcom.py
@@ -46,7 +46,6 @@ from sqlalchemy import (
)
from sqlalchemy.dialects import postgresql
from sqlalchemy.orm import Mapped, aliased, foreign, mapped_column,
relationship
-from sqlalchemy.schema import conv
from sqlalchemy.sql.visitors import cloned_traverse
from airflow._shared.timezones import timezone
@@ -99,7 +98,6 @@ class XComModelV1(TaskInstanceDependencies):
# separately, and enforce uniqueness with DagRun.id instead.
Index("idx_xcom_key", key),
Index("idx_xcom_task_instance", dag_id, task_id, run_id, map_index),
- CheckConstraint(mapped_length >= 0,
name=conv("ck_xcom_mapped_length_not_negative")),
PrimaryKeyConstraint("dag_run_id", "task_id", "map_index", "key",
name="xcom_pkey"),
ForeignKeyConstraint(
[dag_id, task_id, run_id, map_index],
