Postgres: 9.4 SQLAlchemy: 1.0.11 When a sequence is created against a column, calling `metadata.drop_all()` tries to drop the sequence before dropping the table and fails because the table is still referencing the sequence. Manually dropping the table then dropping the sequence works.
The test script is attached. Here is the console output: 2016-03-10 18:44:27,101 INFO sqlalchemy.engine.base.Engine select version() 2016-03-10 18:44:27,101 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,104 INFO sqlalchemy.engine.base.Engine select current_schema() 2016-03-10 18:44:27,104 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,106 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1 2016-03-10 18:44:27,106 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,109 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1 2016-03-10 18:44:27,109 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,110 INFO sqlalchemy.engine.base.Engine show standard_conforming_strings 2016-03-10 18:44:27,110 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,111 INFO sqlalchemy.engine.base.Engine select relname from pg_class c join pg_namespace n on n.oid=c.relnamespace where pg_catalog.pg_table_is_visible(c.oid) and relname=%(name)s 2016-03-10 18:44:27,112 INFO sqlalchemy.engine.base.Engine {'name': u'drop_seq_test'} 2016-03-10 18:44:27,115 INFO sqlalchemy.engine.base.Engine SELECT relname FROM pg_class c join pg_namespace n on n.oid=c.relnamespace where relkind='S' and n.nspname=current_schema() and relname=%(name)s 2016-03-10 18:44:27,115 INFO sqlalchemy.engine.base.Engine {'name': u'drop_seq_col'} 2016-03-10 18:44:27,117 INFO sqlalchemy.engine.base.Engine CREATE SEQUENCE drop_seq_col 2016-03-10 18:44:27,117 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,127 INFO sqlalchemy.engine.base.Engine COMMIT 2016-03-10 18:44:27,129 INFO sqlalchemy.engine.base.Engine CREATE TABLE drop_seq_test ( col INTEGER DEFAULT nextval('drop_seq_col') NOT NULL, source_id SERIAL NOT NULL, PRIMARY KEY (source_id), UNIQUE (col) ) 2016-03-10 18:44:27,129 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,147 INFO sqlalchemy.engine.base.Engine COMMIT 2016-03-10 18:44:27,148 INFO sqlalchemy.engine.base.Engine select relname from pg_class c join pg_namespace n on n.oid=c.relnamespace where pg_catalog.pg_table_is_visible(c.oid) and relname=%(name)s 2016-03-10 18:44:27,148 INFO sqlalchemy.engine.base.Engine {'name': u'drop_seq_test'} 2016-03-10 18:44:27,150 INFO sqlalchemy.engine.base.Engine SELECT relname FROM pg_class c join pg_namespace n on n.oid=c.relnamespace where relkind='S' and n.nspname=current_schema() and relname=%(name)s 2016-03-10 18:44:27,150 INFO sqlalchemy.engine.base.Engine {'name': u'drop_seq_col'} 2016-03-10 18:44:27,151 INFO sqlalchemy.engine.base.Engine DROP SEQUENCE drop_seq_col 2016-03-10 18:44:27,151 INFO sqlalchemy.engine.base.Engine {} 2016-03-10 18:44:27,152 INFO sqlalchemy.engine.base.Engine ROLLBACK Traceback (most recent call last): File "drop-sequence.py", line 17, in <module> metadata.drop_all() File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/schema.py", line 3722, in drop_all tables=tables) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1856, in _run_visitor conn._run_visitor(visitorcallable, element, **kwargs) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1481, in _run_visitor **kwargs).traverse_single(element) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line 121, in traverse_single return meth(obj, **kw) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 871, in visit_metadata table, drop_ok=True, _is_metadata_operation=True) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line 121, in traverse_single return meth(obj, **kw) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 916, in visit_table self.traverse_single(column.default) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line 121, in traverse_single return meth(obj, **kw) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 934, in visit_sequence self.connection.execute(DropSequence(sequence)) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 914, in execute return meth(self, multiparams, params) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 68, in _execute_on_connection return connection._execute_ddl(self, multiparams, params) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 968, in _execute_ddl compiled File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1146, in _execute_context context) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1341, in _handle_dbapi_exception exc_info File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 200, in raise_from_cause reraise(type(exception), exception, tb=exc_tb) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context context) File "/Users/jay/.virtualenvs/pinto/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 450, in do_execute cursor.execute(statement, parameters) sqlalchemy.exc.InternalError: (psycopg2.InternalError) cannot drop sequence drop_seq_col because other objects depend on it DETAIL: default for table drop_seq_test column col depends on sequence drop_seq_col HINT: Use DROP ... CASCADE to drop the dependent objects too. [SQL: 'DROP SEQUENCE drop_seq_col'] Is this a bug? Thanks Jay -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
from sqlalchemy import create_engine, MetaData, Sequence, Integer, Column from sqlalchemy.ext.declarative import declarative_base engine = create_engine('postgresql://localhost/drop_sequence', echo=True) metadata = MetaData(bind=engine) Base = declarative_base(metadata=metadata) id_sequence = Sequence('drop_seq_col') class Station(Base): __tablename__ = 'drop_seq_test' col = Column(Integer, id_sequence, unique=True, nullable=False, server_default=id_sequence.next_value()) source_id = Column(Integer, primary_key=True) metadata.create_all() metadata.drop_all()