test=# create table test1 (x int);
CREATE TABLE
Time: 0.593 ms
test=# select * from test1;
 x 
---
(0 rows)
Time: 0.309 ms
test=# rollback;
ROLLBACK
Time: 1.501 ms
test=# select * from test1;
ERROR: relation "test1" does not exist
LINE 1: select * from test1;
           ^
Time: 0.376 ms

test=# \d    
    List of relations
 Schema | Name | Type | Owner 
--------+------+-------+-------
 public | foo | table | kiwi
 public | test | table | kiwi
(2 rows)

id | name | age | address  | salary
----+-------+-----+-----------+--------
 1 | Paul | 32 | California| 20000
 2 | Allen | 25 | Texas   | 15000
 3 | Teddy | 23 | Norway  | 20000
 4 | Mark | 25 | Rich-Mond | 65000
 5 | David | 27 | Texas   | 85000
 6 | Kim  | 22 | South-Hall| 45000
 7 | James | 24 | Houston  | 10000

runoobdb=# BEGIN;
DELETE FROM COMPANY WHERE AGE = 25;
ROLLBACK;

id | name | age | address  | salary
----+-------+-----+-----------+--------
 1 | Paul | 32 | California| 20000
 2 | Allen | 25 | Texas   | 15000
 3 | Teddy | 23 | Norway  | 20000
 4 | Mark | 25 | Rich-Mond | 65000
 5 | David | 27 | Texas   | 85000
 6 | Kim  | 22 | South-Hall| 45000
 7 | James | 24 | Houston  | 10000

runoobdb=# BEGIN;
DELETE FROM COMPANY WHERE AGE = 25;
COMMIT;

time.clock()
conn = psycopg2.connect(host='172.16.89.80',user="postgres",password="postgres",database="postgres")
cur = conn.cursor()
cur.execute("BEGIN TRANSACTION")    # 开始事务
if __name__=='__main__':
  for i in range(0,1000):
    cur.execute('INSERT INTO test(a, b, c, d) VALUES (%d, %d, %d, %d);'%(i, i, i, i))
  cur.execute('commit')     # 提交事务
  cur.close()
  conn.close()
  print(time.clock())

time.clock()
conn = psycopg2.connect(host='172.16.89.80',user="postgres",password="postgres",database="postgres")
cur = conn.cursor()
if __name__=='__main__':
  for i in range(0,1000):
    cur.execute('INSERT INTO test(a, b, c, d) VALUES (%d, %d, %d, %d);'%(i, i, i, i))
  conn.commit()
  cur.close()
  conn.close()
  print(time.clock())