Some ORACLE DBA Useful Commands

--Sessions with highest CPU consumption:

SELECT s.sid, s.serial#, p.spid as "OS PID",s.username, s.module, st.value/100 as
"CPU sec"
FROM v$sesstat st, v$statname sn, v$session s, v$process p
WHERE sn.name = 'CPU used by this session' -- CPU
AND st.statistic# = sn.statistic#
AND st.sid = s.sid
AND s.paddr = p.addr
AND s.last_call_et < 1800 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours
ORDER BY st.value;


--Sessions with the highest time for a certain wait

SELECT s.sid, s.serial#, p.spid as "OS PID", s.username, s.module, se.time_waited
FROM v$session_event se, v$session s, v$process p
WHERE se.event = '&event_name'
AND s.last_call_et < 1800 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours
AND se.sid = s.sid
AND s.paddr = p.addr
ORDER BY se.time_waited;
SQL> /
Enter value for event_name: db file sequential read


--Sessions with highest DB Time usage

SELECT s.sid, s.serial#, p.spid as "OS PID", s.username, s.module, st.value/100 as
"DB Time (sec)"
, stcpu.value/100 as "CPU Time (sec)", round(stcpu.value / st.value * 100,2) as "%
CPU"
FROM v$sesstat st, v$statname sn, v$session s, v$sesstat stcpu, v$statname sncpu, v
$process p
WHERE sn.name = 'DB time' -- CPU
AND st.statistic# = sn.statistic#
AND st.sid = s.sid
AND sncpu.name = 'CPU used by this session' -- CPU
AND stcpu.statistic# = sncpu.statistic#
AND stcpu.sid = st.sid
AND s.paddr = p.addr
AND s.last_call_et < 1800 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours
AND st.value > 0;


Note: sometimes DB Time can be lower than CPU Time when a session issues long-running recursive
calls. The DB Time statistic doesn't update until the top-level call is finished (versus the CPU statistic that
updates as each call completes).



==========================================
Query to check the Temp  tablespace usage:
==========================================
SELECT total_blocks, free_blocks, total_extents, free_extents FROM
v$sort_segment WHERE tablespace_name = 'TEMP';
  2
TOTAL_BLOCKS FREE_BLOCKS TOTAL_EXTENTS FREE_EXTENTS
------------ ----------- ------------- ------------
     1035648     1035648          8091         8091



Select tablespace_name, sum(bytes)/(1024*1024) from dba_data_files
group by tablespace_name;



Select tablespace_name, sum(bytes)/(1024*1024) FreeSPace from dba_free_space group by tablespace_name;





select sum(free_blocks) from gv$sort_segment where tablespace_name ='TEMP';

==================================================
Query to check tablespace usage of all tablespaces
==================================================
Set lines 1000
SELECT /* + RULE */  df.tablespace_name "Tablespace",
       df.bytes / (1024 * 1024) "Size (MB)",
       SUM(fs.bytes) / (1024 * 1024) "Free (MB)",
       Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) "% Free",
       Round((df.bytes - SUM(fs.bytes)) * 100 / df.bytes) "% Used"
  FROM dba_free_space fs,
       (SELECT tablespace_name,SUM(bytes) bytes
          FROM dba_data_files
         GROUP BY tablespace_name) df
 WHERE fs.tablespace_name (+)  = df.tablespace_name
 GROUP BY df.tablespace_name,df.bytes
UNION ALL
SELECT /* + RULE */ df.tablespace_name tspace,
       fs.bytes / (1024 * 1024),
       SUM(df.bytes_free) / (1024 * 1024),
       Nvl(Round((SUM(fs.bytes) - df.bytes_used) * 100 / fs.bytes), 1),
       Round((SUM(fs.bytes) - df.bytes_free) * 100 / fs.bytes)
  FROM dba_temp_files fs,
       (SELECT tablespace_name,bytes_free,bytes_used
          FROM v$temp_space_header
         GROUP BY tablespace_name,bytes_free,bytes_used) df
 WHERE fs.tablespace_name (+)  = df.tablespace_name
 GROUP BY df.tablespace_name,fs.bytes,df.bytes_free,df.bytes_used
 ORDER BY 4 DESC;







======================================
Query to check temp tablespace usage
======================================

SELECT A.tablespace_name tablespace, D.mb_total,
SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_used,
D.mb_total - SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_free
FROM v$sort_segment A,
(
SELECT B.name, C.block_size, SUM (C.bytes) / 1024 / 1024 mb_total
FROM v$tablespace B, v$tempfile C
WHERE B.ts#= C.ts#
GROUP BY B.name, C.block_size
) D
WHERE A.tablespace_name = D.name
GROUP by A.tablespace_name, D.mb_total;



===========================================================
How to check with the tablespace is permanent of temporary:
===========================================================
If the table space is temporary it should not be in the RMAN backup but if it is permanent it would be in the back up. So check to see which type it is if the data file shows in v$datafile it is permanent if it is in v$tempfile then it is temporary.