dszakallas opened a new pull request #5592: [AIRFLOW-4867] migration script should check if table exists URL: https://github.com/apache/airflow/pull/5592 Make sure you have checked _all_ steps below. ### Jira - [x] My PR addresses the following [AIRFLOW-4867](https://issues.apache.org/jira/browse/AIRFLOW-4867) issues and references them in the PR title. ### Description - [x] Here are some details about my PR, including screenshots of any UI changes: needed to downgrade to Airflow 1.10.2 (db head rev 41f5f12752f8) from Airflow 1.10.4b2 (db head rev 004c1210f153). When running ``` alembic downgrade 41f5f12752f8 ``` I faced the following error ``` INFO [alembic.runtime.migration] Context impl PostgresqlImpl. INFO [alembic.runtime.migration] Will assume transactional DDL. [2019-06-28 20:28:02,375] {migration.py:357} INFO - Running downgrade 004c1210f153 -> 939bb1e647c8, increase queue name size limit [2019-06-28 20:28:03,719] {migration.py:357} INFO - Running downgrade 939bb1e647c8 -> 4ebbffe0a39a, task reschedule fk on cascade delete [2019-06-28 20:28:04,241] {migration.py:357} INFO - Running downgrade 4ebbffe0a39a -> dd4ecb8fbee3, cf5dc11e79ad, a56c9515abdc, Merge heads [2019-06-28 20:29:22,124] {migration.py:357} INFO - Running downgrade dd4ecb8fbee3 -> c8ffec048a3b, Add schedule interval to dag [2019-06-28 20:29:22,468] {migration.py:357} INFO - Running downgrade cf5dc11e79ad -> 41f5f12752f8, drop_user_and_chart Traceback (most recent call last): File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1244, in _execute_context cursor, statement, parameters, context File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 550, in do_execute cursor.execute(statement, parameters) psycopg2.errors.DuplicateTable: relation "users" already exists The above exception was the direct cause of the following exception: Traceback (most recent call last): File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/bin/alembic", line 11, in <module> load_entry_point('alembic==1.0.11', 'console_scripts', 'alembic')() File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/config.py", line 540, in main CommandLine(prog=prog).main(argv=argv) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/config.py", line 534, in main self.run_cmd(cfg, options) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/config.py", line 514, in run_cmd **dict((k, getattr(options, k, None)) for k in kwarg) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/command.py", line 317, in downgrade script.run_env() File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/script/base.py", line 475, in run_env util.load_python_file(self.dir, "env.py") File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/util/pyfiles.py", line 90, in load_python_file module = load_module_py(module_id, path) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/util/compat.py", line 177, in load_module_py spec.loader.exec_module(module) File "<frozen importlib._bootstrap_external>", line 678, in exec_module File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed File "migrations/env.py", line 75, in <module> run_migrations_online() File "migrations/env.py", line 69, in run_migrations_online context.run_migrations() File "<string>", line 8, in run_migrations File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/runtime/environment.py", line 839, in run_migrations self.get_context().run_migrations(**kw) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/runtime/migration.py", line 362, in run_migrations step.migration_fn(**kw) File "/Users/dszakallas/Projects/airflow/airflow/migrations/versions/cf5dc11e79ad_drop_user_and_chart.py", line 66, in downgrade sa.UniqueConstraint('username') File "<string>", line 8, in create_table File "<string>", line 3, in create_table File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/operations/ops.py", line 1248, in create_table return operations.invoke(op) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/operations/base.py", line 345, in invoke return fn(self, operation) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/operations/toimpl.py", line 101, in create_table operations.impl.create_table(table) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/ddl/impl.py", line 252, in create_table self._exec(schema.CreateTable(table)) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/alembic/ddl/impl.py", line 134, in _exec return conn.execute(construct, *multiparams, **params) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 988, in execute return meth(self, multiparams, params) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/sql/ddl.py", line 72, in _execute_on_connection return connection._execute_ddl(self, multiparams, params) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1050, in _execute_ddl compiled, File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1248, in _execute_context e, statement, parameters, cursor, context File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1466, in _handle_dbapi_exception util.raise_from_cause(sqlalchemy_exception, exc_info) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 399, in raise_from_cause reraise(type(exception), exception, tb=exc_tb, cause=cause) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 153, in reraise raise value.with_traceback(tb) File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1244, in _execute_context cursor, statement, parameters, context File "/Users/dszakallas/.pyenv/versions/3.6.6/envs/pds-airflow/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 550, in do_execute cursor.execute(statement, parameters) sqlalchemy.exc.ProgrammingError: (psycopg2.errors.DuplicateTable) relation "users" already exists [SQL: CREATE TABLE users ( id SERIAL NOT NULL, 69 sa.UniqueConstraint('username') username VARCHAR(250), email VARCHAR(500), password VARCHAR(255), superuser BOOLEAN, PRIMARY KEY (id), UNIQUE (username) ) ] (Background on this error at: http://sqlalche.me/e/f405) ``` I 'fixed' the migration script with only creating the tables if they exist: After this fix the migrations successfully ran for me. ### Tests - [x] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason: I don't think this can be unit tested. ### Commits - [ ] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)": 1. Subject is separated from body by a blank line 1. Subject is limited to 50 characters (not including Jira issue reference) 1. Subject does not end with a period 1. Subject uses the imperative mood ("add", not "adding") 1. Body wraps at 72 characters 1. Body explains "what" and "why", not "how" ### Documentation - [x] In case of new functionality, my PR adds documentation that describes how to use it. - All the public functions and the classes in the PR contain docstrings that explain what it does - If you implement backwards incompatible changes, please leave a note in the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so we can assign it to a appropriate release ### Code Quality - [x] Passes `flake8`
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