e.g. DBURI=postgres://user:pass@host:port/name python alembic_fk_deferrable.py

alembic_fk_deferrable.py

import os
import sqlalchemy as sa
engine = sa.create_engine(os.environ['DBURI'])
meta = sa.MetaData(bind=engine, reflect=True)

tmpl = """
op.drop_constraint('{name}', '{source}')
op.create_foreign_key('{name}', '{source}', '{referent}', ['{local_cols}'], ['{remote_cols}'], deferrable=True)
"""

for name, table in meta.tables.items():
    for fk in table.foreign_keys:
        c = fk.constraint
        print tmpl.format(name=c.name,
                          source=c.table.name,
                          referent=fk.column.table.name,
                          local_cols=c.columns[0],
                          remote_cols=fk.column.name).strip()