如何检查PG数据库阻塞事务

一 检查阻塞

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,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 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