René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Most queries raise non-fatal `ValueError: Transaction is already committed`","articleBody":"## Expected Behavior\r\nConnection pool does not raise exceptions\r\n\r\n## Actual Behavior\r\nConnection pool raises non-fatal exceptions for SELECT/INSERT transactions\r\n\r\n\r\n## Steps to Reproduce the Problem\r\n```python\r\nfrom sqlalchemy import Column, Integer, MetaData, select, Text, Table, create_engine\r\n\r\nproject_id = 'foo'\r\ninstance_id = 'bar'\r\ndatabase = 'baz'\r\n\r\nspanner_uri = f'spanner:///projects/{project_id}/instances/{instance_id}/databases/{database}'\r\n\r\n# Create a table with one `Text`-type column\r\nengine = create_engine(spanner_uri)\r\nmetadata = MetaData(bind=engine)\r\nt = Table(\"TestTable\", metadata, Column(\"test_column\", Text, nullable=False))\r\nmetadata.create_all(engine)\r\n\r\nwith engine.begin() as conn:\r\n    results = conn.execute(select([t.c.test_column])).fetchall()\r\n\r\nprint(results)\r\n```\r\n```shell\r\naderk@aderk ~/q/pyle (u/aderk/labdb-spanner)\u003e python txn_bug.py \r\nException during reset or similar\r\nTraceback (most recent call last):\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/sqlalchemy/pool/base.py\", line 697, in _finalize_fairy\r\n    fairy._reset(pool)\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/sqlalchemy/pool/base.py\", line 893, in _reset\r\n    pool._dialect.do_rollback(self)\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/google/cloud/sqlalchemy_spanner/sqlalchemy_spanner.py\", line 773, in do_rollback\r\n    dbapi_connection.rollback()\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/google/cloud/spanner_dbapi/connection.py\", line 267, in rollback\r\n    self._transaction.rollback()\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/google/cloud/spanner_v1/transaction.py\", line 113, in rollback\r\n    self._check_state()\r\n  File \"/usr/local/google/home/aderk/.virtualenvs/pyle/lib/python3.8/site-packages/google/cloud/spanner_v1/transaction.py\", line 68, in _check_state\r\n    raise ValueError(\"Transaction is already committed\")\r\nValueError: Transaction is already committed\r\n[]\r\n```\r\n\r\n## Specifications\r\n\r\n- Version: Python 3.8.8 (default, Apr  1 2021, 17:00:06) \r\n1c9be70f901ca016c357ced66fe258f01b694787\r\n- Platform: Linux","author":{"url":"https://github.com/aderk","@type":"Person","name":"aderk"},"datePublished":"2021-08-20T21:05:08.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/103/python-spanner-sqlalchemy/issues/103"}