Hello,
As I try alembic (for the first time), I ran into the following stack
traces when attempting to conduct a "nasty" migration.
I call it "nasty" because the original model was based on sqlalchemy v0.9 +
python 2.7 and the new model is sqlalchemy v1.2 + python 3.6.
ON TOP OF THAT, it's a massive table and model restructuring. Backend is
postgres.
I am thinking that I can leverage alembic to do the heavy lifting of
creating/dropping stuff while I can interject my own bulk_inserts and
bulk_updates and preserve the existing data. Something like:
// versions/deadbeef_nasty.py
def upgrade():
op.drop_table(...)
op.drop_table(...)
...
# Here is where I am planning to add my bulk_inserts and bulk_updates
op.add_column(...)
op.drop_column(...)
...
*Is this a reasonable approach?*
*With regards to the stack traces, they differ between online (first stack)
and offline (second). Hence, this post.*
*Does that make sense?*
*Question: are online migrations run within a single transaction or not?*
*Thanks!!!*
$ alembic upgrade head
/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/psycopg2/__init__.py:144: UserWarning: The psycopg2 wheel package
will be renamed from release 2.8; in order to keep installing from binary
please use "pip install psycopg2-binary" instead. For details see:
<http://initd.org/psycopg/docs/install.html#binary-install-from-pypi>.
""")
INFO [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO [alembic.runtime.migration] Will assume transactional DDL.
INFO [alembic.runtime.migration] Running upgrade 55ebe08ba589 ->
b6c3cd0ef4cb, version 1
Traceback (most recent call last):
File "/Users/hp3/.pyenv/versions/server_py2/bin/alembic", line 11, in
<module>
sys.exit(main())
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/config.py", line 486, in main
CommandLine(prog=prog).main(argv=argv)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/config.py", line 480, in main
self.run_cmd(cfg, options)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/config.py", line 463, in run_cmd
**dict((k, getattr(options, k, None)) for k in kwarg)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/command.py", line 254, in upgrade
script.run_env()
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/script/base.py", line 427, in run_env
util.load_python_file(self.dir, 'env.py')
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/util/pyfiles.py", line 81, in load_python_file
module = load_module_py(module_id, path)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/util/compat.py", line 135, in load_module_py
mod = imp.load_source(module_id, path, fp)
File "alembic/env.py", line 72, in <module>
run_migrations_online()
File "alembic/env.py", line 67, in run_migrations_online
context.run_migrations()
File "<string>", line 8, in run_migrations
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/runtime/environment.py", line 836, in run_migrations
self.get_context().run_migrations(**kw)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/runtime/migration.py", line 330, in run_migrations
step.migration_fn(**kw)
File "/Users/hp3/Documents/python_workspace/Plannotate2_Cloud/src/server/
alembic/versions/b6c3cd0ef4cb_version_1.py", line 38, in upgrade
op.drop_table('groups_history')
File "<string>", line 8, in drop_table
File "<string>", line 3, in drop_table
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/operations/ops.py", line 1187, in drop_table
operations.invoke(op)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/operations/base.py", line 319, in invoke
return fn(self, operation)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/operations/toimpl.py", line 70, in drop_table
operation.to_table(operations.migration_context)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/ddl/impl.py", line 198, in drop_table
self._exec(schema.DropTable(table))
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/alembic/ddl/impl.py", line 115, in _exec
return conn.execute(construct, *multiparams, **params)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/base.py", line 729, in execute
return meth(self, multiparams, params)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/sql/ddl.py", line 69, in _execute_on_connection
return connection._execute_ddl(self, multiparams, params)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/base.py", line 783, in _execute_ddl
compiled
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/base.py", line 958, in _execute_context
context)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/base.py", line 1160, in _handle_dbapi_exception
exc_info
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/base.py", line 951, in _execute_context
context)
File "/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-
packages/sqlalchemy/engine/default.py", line 436, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.InternalError: (InternalError) cannot drop table
groups_history because other objects depend on it
DETAIL: constraint folders_history_id_fkey on table folders_history depends
on table groups_history
constraint projects_history_id_fkey on table projects_history depends on
table groups_history
constraint userprofiles_history_id_fkey on table userprofiles_history
depends on table groups_history
HINT: Use DROP ... CASCADE to drop the dependent objects too.
*When I try the same migration "offline" the stack trace looks like this:*
File "/Users/hp3/.pyenv/versions/server_py2/bin/alembic", line 11, in
<module>
sys.exit(main())
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/config.py"
, line 486, in main
CommandLine(prog=prog).main(argv=argv)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/config.py"
, line 480, in main
self.run_cmd(cfg, options)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/config.py"
, line 463, in run_cmd
**dict((k, getattr(options, k, None)) for k in kwarg)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/command.py"
, line 254, in upgrade
script.run_env()
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/script/base.py"
, line 427, in run_env
util.load_python_file(self.dir, 'env.py')
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/util/pyfiles.py"
, line 81, in load_python_file
module = load_module_py(module_id, path)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/util/compat.py"
, line 135, in load_module_py
mod = imp.load_source(module_id, path, fp)
File "alembic/env.py", line 70, in <module>
run_migrations_offline()
File "alembic/env.py", line 45, in run_migrations_offline
context.run_migrations()
File "<string>", line 8, in run_migrations
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/runtime/environment.py"
, line 836, in run_migrations
self.get_context().run_migrations(**kw)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/runtime/migration.py"
, line 330, in run_migrations
step.migration_fn(**kw)
File
"/Users/hp3/Documents/python_workspace/Plannotate2_Cloud/src/server/alembic/versions/b6c3cd0ef4cb_version_1.py"
, line 39, in upgrade
op.drop_index('ix_layers_history_page_id', table_name='layers_history')
File "<string>", line 8, in drop_index
File "<string>", line 3, in drop_index
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/operations/ops.py"
, line 964, in drop_index
return operations.invoke(op)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/operations/base.py"
, line 319, in invoke
return fn(self, operation)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/operations/toimpl.py"
, line 94, in drop_index
operation.to_index(operations.migration_context)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/operations/ops.py"
, line 921, in to_index
schema=self.schema, **self.kw)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/alembic/operations/schemaobj.py"
, line 131, in index
**kw)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/sql/schema.py"
, line 2860, in __init__
ColumnCollectionMixin.__init__(self, *columns)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/sql/schema.py"
, line 2259, in __init__
self._set_parent_with_dispatch(self._pending_colargs[0].table)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/sql/base.py"
, line 434, in _set_parent_with_dispatch
self.dispatch.after_parent_attach(self, parent)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/event/attr.py"
, line 221, in __call__
fn(*args, **kw)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/sql/naming.py"
, line 142, in _constraint_name
newname = _constraint_name_for_table(const, table)
File
"/Users/hp3/.pyenv/versions/2.7.14/envs/server_py2/lib/python2.7/site-packages/sqlalchemy/sql/naming.py"
, line 118, in _constraint_name_for_table
"constraint_name" in convention
TypeError: argument of type 'instance' is not iterable
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