DBA Monitoring Scripts

Explain plan for an sql query .

set linesize 400
set pagesize 999
explain plan for << sql query >>;
select * from table(dbms_xplan.display);

Explain plan using SQL_ID

select * from table(DBMS_XPLAN.DISPLAY_CURSOR('1f24a8hhfpcnc'));
or
select * from table(DBMS_XPLAN.DISPLAY_awr('1f24a8hhfpcnc'));

Get the ddl of objects.

set long 90000;
SELECT dbms_metadata.get_ddl('PROCEDURE','PUSH_JOB') FROM dual;

query to check if parameters can be changed dynamically without bouncing the DB
select name,ISSYS_MODIFIABLE from v$parameter where name in ('sga_max_size','shared_pool_size');

find your session sid
select distinct sid from v$mystat;


sql_id sql query execution plan history

select ss.snap_id, ss.instance_number node,s.ROWS_PROCESSED_TOTAL "ROWS", begin_interval_time, sql_id, plan_hash_value plan_hash, 
nvl(executions_delta,0) execs,
(elapsed_time_delta/decode(nvl(executions_delta,0),0,1,executions_delta))/1000000 avg_etime,
(buffer_gets_delta/decode(nvl(buffer_gets_delta,0),0,1,executions_delta)) avg_lio
from DBA_HIST_SQLSTAT S, DBA_HIST_SNAPSHOT SS
where sql_id = '1f24a8hhfpcnc'
and ss.snap_id = S.snap_id
and ss.instance_number = S.instance_number
and executions_delta > 0
and trunc(ss.begin_interval_time) >= trunc(sysdate -20)
order by 1,2, 3 ;

sql for Blocking session :-

select sid,serial#,status,logon_time,BLOCKING_SESSION,EVENT,USERNAME from v$session where BLOCKING_SESSION is not null;

session count details  :-
select * from (select username,status,count(*) mycount from v$session group by username,status order by mycount desc) where rownum < 5;

Database Long running sessions :-

 select s.username O,s.sid d,osuser S,spid I,status,(hsecs - value)/(100*60) t,
    decode(command,0,'NONE',1,'Create Tab',2,'Insert',3,'Select',6,'Update',
    7,'Delete',42,'Alter Sess',44,'Commit',45,'Rollback',47,'PL/SQL Exe',
    'UNKNOWN') c,
   s.program P
    from v$session s, v$process p, v$sesstat q, v$timer t
   where s.paddr = p.addr
    and s.sid = q.sid
    and statistic# = (select statistic# from v$statname
   where name = 'process last non-idle time')
  and status <> 'INACTIVE'
 order by s.username, t desc ;

Which SQL is being executed

 select user,sql_id,sql_hash_value, count(*) from gv$session
Where Status = 'ACTIVE' group by user, sql_id, sql_hash_value Order By 4 Desc;

select sql_text,users_executing from v$sql where hash_value = <value from above>;

Top wait events
select event, state, count(*) from gv$session_wait group by event, state order by 3 desc;