查看錶鎖資訊，是DBA常用的指令碼之一。

實驗環境：

CentOS 7

PG 10.4

先通過A視窗執行

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

開啟B視窗執行

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

說明只鎖住了行，對於更新其他行沒有影響。

再開啟一個視窗檢視資訊

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)

補充：如何檢視PostgreSQL正在執行的SQL以及鎖資訊

檢視當前正在執行的SQL

SELECT 
procpid,start,now() - start AS lap,current_query 
FROM 
(SELECT 
backendid,pg_stat_get_backend_pid(S.backendid) AS procpid,pg_stat_get_backend_activity_start(S.backendid) AS start,pg_stat_get_backend_activity(S.backendid) AS current_query 
FROM 
(SELECT pg_stat_get_backend_idset() AS backendid) AS S 
) AS S 
WHERE 
current_query <> '<IDLE>' 
ORDER BY 
lap DESC; 
procpid：程序id 
start：程序開始時間 
lap：經過時間 
current_query：執行中的sql 
怎樣停止正在執行的sql 
SELECT pg_cancel_backend(程序id); 
或者用系統函式 
kill -9 程序id;

檢視資料庫目前是否有鎖

-- 檢視當前事務鎖等待、持鎖資訊的SQL
with  
t_wait as  
(  
 select a.mode,a.locktype,a.database,a.relation,a.page,a.tuple,a.classid,a.granted,a.objid,a.objsubid,a.pid,a.virtualtransaction,a.virtualxid,a.transactionid,a.fastpath,b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name  
  from pg_locks a,pg_stat_activity b where a.pid=b.pid and not a.granted  
),t_run as  
(  
 select a.mode,pg_stat_activity b where a.pid=b.pid and a.granted  
),t_overlap as  
(  
 select r.* from t_wait w join t_run r on  
 (  
  r.locktype is not distinct from w.locktype and  
  r.database is not distinct from w.database and  
  r.relation is not distinct from w.relation and  
  r.page is not distinct from w.page and  
  r.tuple is not distinct from w.tuple and  
  r.virtualxid is not distinct from w.virtualxid and  
  r.transactionid is not distinct from w.transactionid and  
  r.classid is not distinct from w.classid and  
  r.objid is not distinct from w.objid and  
  r.objsubid is not distinct from w.objsubid and  
  r.pid <> w.pid  
 )  
),t_unionall as  
(  
 select r.* from t_overlap r  
 union all  
 select w.* from t_wait w  
)  
select locktype,datname,relation::regclass,page,tuple,virtualxid,transactionid::text,classid::regclass,objid,objsubid,string_agg(  
'Pid: '||case when pid is null then 'NULL' else pid::text end||chr(10)||  
'Lock_Granted: '||case when granted is null then 'NULL' else granted::text end||',Mode: '||case when mode is null then 'NULL' else mode::text end||',FastPath: '||case when fastpath is null then 'NULL' else fastpath::text end||',VirtualTransaction: '||case when virtualtransaction is null then 'NULL' else virtualtransaction::text end||',Session_State: '||case when state is null then 'NULL' else state::text end||chr(10)||  
'Username: '||case when usename is null then 'NULL' else usename::text end||',Database: '||case when datname is null then 'NULL' else datname::text end||',Client_Addr: '||case when client_addr is null then 'NULL' else client_addr::text end||',Client_Port: '||case when client_port is null then 'NULL' else client_port::text end||',Application_Name: '||case when application_name is null then 'NULL' else application_name::text end||chr(10)||  
'Xact_Start: '||case when xact_start is null then 'NULL' else xact_start::text end||',Query_Start: '||case when query_start is null then 'NULL' else query_start::text end||',Xact_Elapse: '||case when (now()-xact_start) is null then 'NULL' else (now()-xact_start)::text end||',Query_Elapse: '||case when (now()-query_start) is null then 'NULL' else (now()-query_start)::text end||chr(10)||  
'SQL (Current SQL in Transaction): '||chr(10)|| 
case when query is null then 'NULL' else query::text end,chr(10)||'--------'||chr(10)  
order by  
 ( case mode  
  when 'INVALID' then 0  
  when 'AccessShareLock' then 1  
  when 'RowShareLock' then 2  
  when 'RowExclusiveLock' then 3  
  when 'ShareUpdateExclusiveLock' then 4  
  when 'ShareLock' then 5  
  when 'ShareRowExclusiveLock' then 6  
  when 'ExclusiveLock' then 7  
  when 'AccessExclusiveLock' then 8  
  else 0  
 end ) desc,(case when granted then 0 else 1 end) 
) as lock_conflict 
from t_unionall  
group by  
locktype,relation,classid,objsubid ; 

以上為個人經驗，希望能給大家一個參考，也希望大家多多支援我們。如有錯誤或未考慮完全的地方，望不吝賜教。