课程作业
1.以默认方式启动事务1，修改事务隔离级别，查看transaction_isolation
2.以读写方式启动事务2，创建新表，修改事务为只读事务，查看transaction_read_only，并向表中插入记录
3.启动事务3，对表进行增删改查，并用到创建savepoint，回滚savepoint和删除savepoint
4.清理数据
omm=#
omm=#
omm=#
omm=# START TRANSACTION;
START TRANSACTION
omm=# select * from pg_class limit 1;
relname | relnamespace | reltype | reloftype | relowner | relam | relfilenode | reltablespace |
relpages | reltuples | relallvisible | reltoastrelid | reltoastidxid | reldeltarelid | reldeltaidx |
relcudescrelid | relcudescidx | relhasindex | relisshared | relpersistence | relkind | relnatts | re
lchecks | relhasoids | relhaspkey | relhasrules | relhastriggers | relhassubclass | relcmprs | relhas
clusterkey | relrowmovement | parttype | relfrozenxid | relacl | reloptions | relreplident
| relfrozenxid64 | relbucket | relbucketkey
--------------+--------------+---------+-----------+----------+-------+-------------+---------------+
----------+-----------+---------------+---------------+---------------+---------------+-------------+
----------------+--------------+-------------+-------------+----------------+---------+----------+---
--------+------------+------------+-------------+----------------+----------------+----------+-------
-----------+----------------+----------+--------------+-------------------+------------+-------------
-+----------------+-----------+--------------
pg_statistic | 11 | 11334 | 0 | 10 | 0 | 13689 | 0 |
18 | 476 | 18 | 2840 | 0 | 0 | 0 |
0 | 0 | t | f | p | r | 29 |
| f | n | 0 | {omm=arwdDxt/omm} | | n
| 7891 | |
(1 row)
0 | f | f | f | f | f | 0 | f
omm=# END;
COMMIT
omm=# BEGIN;
BEGIN
omm=# SET LOCAL TRANSACTION ISOLATION LEVEL READ COMMITTED READ ONLY;
SET
omm=# show transaction_read_only;
omm=# transaction_read_only
-----------------------
on
(1 row)
select * from pg_class limit 1;
relname | relnamespace | reltype | reloftype | relowner | relam | relfilenode | reltablespace |
relpages | reltuples | relallvisible | reltoastrelid | reltoastidxid | reldeltarelid | reldeltaidx |
relcudescrelid | relcudescidx | relhasindex | relisshared | relpersistence | relkind | relnatts | re
lchecks | relhasoids | relhaspkey | relhasrules | relhastriggers | relhassubclass | relcmprs | relhas
clusterkey | relrowmovement | parttype | relfrozenxid | relacl | reloptions | relreplident
| relfrozenxid64 | relbucket | relbucketkey
--------------+--------------+---------+-----------+----------+-------+-------------+---------------+
----------+-----------+---------------+---------------+---------------+---------------+-------------+
----------------+--------------+-------------+-------------+----------------+---------+----------+---
--------+------------+------------+-------------+----------------+----------------+----------+-------
-----------+----------------+----------+--------------+-------------------+------------+-------------
-+----------------+-----------+--------------
pg_statistic | 11 | 11334 | 0 | 10 | 0 | 13689 | 0 |
18 | 476 | 18 | 2840 | 0 | 0 | 0 |
0 | 0 | t | f | p | r | 29 |
0 | f | f | f | f | f | 0 | f
| f | n | 0 | {omm=arwdDxt/omm} | | n
| 7891 | |
(1 row)
omm=# create schema tpcds10;
ERROR: cannot execute CREATE SCHEMA in a read-only transaction
omm=# commit;
ROLLBACK
omm=# show transaction_isolation;
transaction_isolation
-----------------------
read committed
(1 row)
omm=# START TRANSACTION ISOLATION LEVEL repeatable read READ WRITE;
START TRANSACTION
show transaction_isolation;
omm=# transaction_isolation
-----------------------
repeatable read
(1 row)
omm=# show transaction_read_only;
off
transaction_read_only
-----------------------
(1 row)
omm=# select * from pg_class limit 1;
relname | relnamespace | reltype | reloftype | relowner | relam | relfilenode | reltablespace |
relpages | reltuples | relallvisible | reltoastrelid | reltoastidxid | reldeltarelid | reldeltaidx |
relcudescrelid | relcudescidx | relhasindex | relisshared | relpersistence | relkind | relnatts | re
lchecks | relhasoids | relhaspkey | relhasrules | relhastriggers | relhassubclass | relcmprs | relhas
clusterkey | relrowmovement | parttype | relfrozenxid | relacl | reloptions | relreplident
| relfrozenxid64 | relbucket | relbucketkey
--------------+--------------+---------+-----------+----------+-------+-------------+---------------+
----------+-----------+---------------+---------------+---------------+---------------+-------------+
----------------+--------------+-------------+-------------+----------------+---------+----------+---
--------+------------+------------+-------------+----------------+----------------+----------+-------
-----------+----------------+----------+--------------+-------------------+------------+-------------
18 | 476 | 18 | 2840 | 0 | 0 | 0 |
-+----------------+-----------+--------------
pg_statistic | 11 | 11334 | 0 | 10 | 0 | 13689 | 0 |
0 | 0 | t | f | p | r | 29 |
0 | f | f | f | f | f | 0 | f
| f | n | 0 | {omm=arwdDxt/omm} | | n
| 7891 | |
(1 row)
omm=# create schema tpcds10;
CREATE SCHEMA
omm=# rollback;
ROLLBACK
omm=#
omm=# \dn+ tpcds10;
List of schemas
Name | Owner | Access privileges | Description
------+-------+-------------------+-------------
(0 rows)
omm=#
omm=#
omm=# CREATE TABLE table1(a int);
CREATE TABLE
omm=# START TRANSACTION;
START TRANSACTION
omm=# INSERT INTO table1 VALUES (1);
INSERT 0 1
omm=#
omm=#
omm=#
omm=# SAVEPOINT my_savepoint;
SAVEPOINT
omm=# INSERT INTO table1 VALUES (2);
INSERT 0 1
omm=#
omm=#
omm=# ROLLBACK TO SAVEPOINT my_savepoint;
ROLLBACK
omm=#
omm=# RELEASE SAVEPOINT my_savepoint;
RELEASE
omm=# INSERT INTO table1 VALUES (3);
INSERT 0 1
omm=# COMMIT;
COMMIT
omm=#
omm=#
omm=# SELECT * FROM table1;
a
---
1
3
(2 rows)
omm=#
omm=#
omm=#
omm=#
omm=#
omm=#
omm=#
omm=# drop table t1;
omm=# drop table t2;
omm=#
