Postgresql - 查看锁表信息

查看表锁信息，是DBA常用的脚本之一。

实验环境：

CentOS 7

PG 10.4

先通过A窗口执行

mytest=# begin;

BEGIN

mytest=# update t1 set col1 = 'a' where id =1 ;

UPDATE 1

mytest=#

打开B窗口执行

mytest=# begin;

BEGIN

mytest=# update t1 set col1 = 'b' where id =2;

UPDATE 1

mytest=# update t1 set col1 = 'b' where id =1;

等待了

说明只锁住了行，对于更新其他行没有影响。

再打开一个窗口查看信息

SELECT

a.datname,

locktype,

virtualtransaction,

transactionid,

nspname,

relname,

mode,

granted,

cast(date_trunc('second',query_start) AS timestamp) AS query_start

FROM

pg_locks

LEFT OUTER JOIN pg_class ON (pg_locks.relation = pg_class.oid)

LEFT OUTER JOIN pg_namespace ON (pg_namespace.oid = pg_class.relnamespace),

pg_stat_activity a

WHERE NOT pg_locks.pid = pg_backend_pid()

AND pg_locks.pid=a.pid;

datname | locktype | virtualtransaction | transactionid | nspname | relname | mode | granted | query_start

---------+---------------+--------------------+---------------+---------+---------+------------------+---------+---------------------

mytest | relation | 7/332 | | public | t1 | RowExclusiveLock | t | 2018-06-28 06:29:58

mytest | virtualxid | 7/332 | | | | ExclusiveLock | t | 2018-06-28 06:29:58

mytest | relation | 6/42 | | public | t1 | RowExclusiveLock | t | 2018-06-28 06:29:35

mytest | virtualxid | 6/42 | | | | ExclusiveLock | t | 2018-06-28 06:29:35

mytest | transactionid | 7/332 | 712 | | | ExclusiveLock | t | 2018-06-28 06:29:58

mytest | transactionid | 6/42 | 711 | | | ExclusiveLock | t | 2018-06-28 06:29:35

mytest | transactionid | 7/332 | 711 | | | ShareLock | f | 2018-06-28 06:29:58

mytest | tuple | 7/332 | | public | t1 | ExclusiveLock | t | 2018-06-28 06:29:58

(8 rows)