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import psycopg2
import traceback
# Change the table here to something the user can create tables in ...
db = psycopg2.connect('dbname=test')
cursor = db.cursor()
print('Creating tables and sample data')
cursor.execute('''
CREATE TEMPORARY TABLE foo (
id int PRIMARY KEY
)''')
cursor.execute('''
CREATE TEMPORARY TABLE bar (
id int PRIMARY KEY,
foo_id int,
CONSTRAINT bar_foo_fk FOREIGN KEY (foo_id) REFERENCES foo(id) DEFERRABLE
)''')
cursor.execute('INSERT INTO foo VALUES (1)')
cursor.execute('INSERT INTO bar VALUES (1, 1)')
db.commit()
print('Deferring constraint and breaking referential integrity')
cursor.execute('SET CONSTRAINTS bar_foo_fk DEFERRED')
cursor.execute('UPDATE bar SET foo_id = 42 WHERE id = 1')
print('Committing (this should fail)')
try:
db.commit()
except:
traceback.print_exc()
print('Rolling back connection')
db.rollback()
print('Running a trivial query')
try:
cursor.execute('SELECT TRUE')
except:
traceback.print_exc()
print('db.closed:', db.closed)
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