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Intermittent AlreadyExists 409 Error on Insert Mutation Retry #15883
Description
Environment details
- OS type and version: Linux, Debian
- Python version: Python 3.12.2
- pip version: pip 24.2
google-cloud-spannerversion: google-cloud-spanner==3.57.0
Steps to reproduce
I'm intermittently experiencing AlreadyExists: 409 errors when performing batch writes using the mutations API. It appears the sequence of events is:
- Attempt to commit a batch mutation insert
- The commit aborts
- The library retries the commit
- The commit fails during the retry because the row(s) already exist
It's as if the transaction isn't being rolled back in between commit attempts, so the commit in the retry will fail.
I'm looking at
_retry_on_aborted_exception
and
Batch.commit
and I don't see explicit rollback requests between commits on retry.
Code example
with database.batch() as batch:
for table, column, values in stuff_to_write:
batch.insert(table=table, columns=columns, values=values)Stack trace
with self.database.batch() as batch:
File "lib/python3.12/site-packages/google/cloud/spanner_v1/database.py", line 1354, in __exit__
self._batch.commit(
File "lib/python3.12/site-packages/google/cloud/spanner_v1/batch.py", line 262, in commit
response = _retry_on_aborted_exception(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "ib/python3.12/site-packages/google/cloud/spanner_v1/_helpers.py", line 522, in _retry_on_aborted_exception
return func()
^^^^^^
File "lib/python3.12/site-packages/google/cloud/spanner_v1/batch.py", line 260, in wrapped_method
return commit_method()
^^^^^^^^^^^^^^^
File "lib/python3.12/site-packages/google/cloud/spanner_v1/services/spanner/client.py", line 2133, in commit
response = rpc(
^^^^
File "lib/python3.12/site-packages/google/api_core/gapic_v1/method.py", line 131, in __call__
return wrapped_func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "lib/python3.12/site-packages/google/api_core/retry/retry_unary.py", line 293, in retry_wrapped_func
return retry_target(
^^^^^^^^^^^^^
File "lib/python3.12/site-packages/google/api_core/retry/retry_unary.py", line 153, in retry_target
_retry_error_helper(
File "lib/python3.12/site-packages/google/api_core/retry/retry_base.py", line 212, in _retry_error_helper
raise final_exc from source_exc
File "lib/python3.12/site-packages/google/api_core/retry/retry_unary.py", line 144, in retry_target
result = target()
^^^^^^^^
File "lib/python3.12/site-packages/google/api_core/timeout.py", line 130, in func_with_timeout
return func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "lib/python3.12/site-packages/google/api_core/grpc_helpers.py", line 78, in error_remapped_callable
raise exceptions.from_grpc_error(exc) from exc
google.api_core.exceptions.AlreadyExists: 409 Row [a44...] in table ... already exists
Activity
[-]AlreadyExists 409 Error on Insert Mutation Retry[/-][+]Intermittent AlreadyExists 409 Error on Insert Mutation Retry[/+]chalmerlowe commentedon Mar 2, 2026
This issue was moved from the following repo as part of the monorepo migration: googleapis/python-spanner
sinhasubham commentedon May 12, 2026
Already fixed as part of this change: googleapis/python-spanner#1491