Thursday, 25 July 2019

find and kill... that's harsh. find problematic IO intensive oracle operations and prevent them causing too much carnage...

This is a continuation of my IOPs challenges.

This is a non DBA's cheat sheet for finding IO in a standard oracle database

Good to find out what queries are smashing the disk:

select
   p.spid,
   s.sid,
   s.serial#,
   s.process cli_process,
   s.status,t.disk_reads,
   s.last_call_et/3600 last_call_et_Hrs,
   s.action,
   s.program,
   t.sql_fulltext
from
   v$session s,
   v$sqlarea t,
   v$process p
where
   s.sql_address = t.address
and
   s.sql_hash_value = t.hash_value
and
   p.addr = s.paddr
-- and
--t.disk_reads > 10
order by
   t.disk_reads desc;

PID                            SID    SERIAL# CLI_PROCESS              STATUS   DISK_READS LAST_CALL_ET_HRS ACTION                                                           PROGRAM                                          SQL_FULLTEXT                                                                   
------------------------ ---------- ---------- ------------------------ -------- ---------- ---------------- ---------------------------------------------------------------- ------------------------------------------------ --------------------------------------------------------------------------------
2924                           3880      15998 1234                     INACTIVE   48832423           4.4775                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
4939                           7678       8934 1234                     INACTIVE   48832423       4.57472222                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
4935                          10191      19604 1234                     INACTIVE   48832423       4.51472222                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
3679                          10175      40187 1234                     INACTIVE   20300027            10.71                                                                  JDBC Thin Client                                 SELECT SDAN8,SDQTYT,SDPPDJ,SDUORG,SDDCT,SDFRGD,SDDELN,SDPA8,SDADTM,SDTHRP,SDSRP2
4931                          19066        290 1234                     INACTIVE   16277598       6.58472222                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
2181                           1311       2983 1234                     INACTIVE    7032445       41.3938889                                                                  JDBC Thin Client                                 SELECT  DISTINCT GLDOC,GLPOST,GLLT,GLDGJ,GLKCO,GLDCT,GLEXA,GLR1,GLRE,GLPN,GLICU,
9811                          15283      13699 1234                     INACTIVE    7032445       41.3938889                                                                  JDBC Thin Client                                 SELECT  DISTINCT GLDOC,GLPOST,GLLT,GLDGJ,GLKCO,GLDCT,GLEXA,GLR1,GLRE,GLPN,GLICU,
7281                          15258       2380 1234                     INACTIVE    3379248       37.2380556                                                                  JDBC Thin Client                                 SELECT SDAN8,SDQTYT,SDPPDJ,SDUORG,SDDCT,SDFRGD,SDDELN,SDPA8,SDADTM,SDTHRP,SDSRP2
27197                            41       1604 1234                     INACTIVE    2911686       27.3166667                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
13675                         16529        830 1234                     INACTIVE    1207700       48.6297222                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G
29908                          2602       9964 1234                     INACTIVE    1207700       48.6297222                                                                  JDBC Thin Client                                 SELECT T1.GMANS,T0.GLODCT,T2.MCADDS,T2.MCRP20,T0.GLALT4,T2.MCCLNU,T0.GLPYID,T0.G

Remember that
If the session STATUS is currently ACTIVE, then the value represents the elapsed time in seconds since the session has become active.
If the session STATUS is currently INACTIVE, then the value represents the elapsed time in seconds since the session has become inactive.

Handy to also look at longops to know how long they might take to complete, if they are listed there.
 
   select
   l.sid,
   l.sofar,
   l.totalwork,
   l.start_time,
   l.last_update_time,
   s.sql_text
from
   v$session_longops l      
left outer join
    v$sql s
on
   s.hash_value = l.sql_hash_value
and
   s.address = l.sql_address
and
   s.child_number = 0
   order by TOTALWORK desc;

The above is cool for seeing long operations, if you want to see active longops, add this where clause:
 
   select
   l.sid,
   l.sofar,
   l.totalwork,
   l.start_time,
   l.last_update_time,
   s.sql_text
from
   v$session_longops l      
left outer join
    v$sql s
on
   s.hash_value = l.sql_hash_value
and
   s.address = l.sql_address
and
   s.child_number = 0
where sofar < totalwork
   order by TOTALWORK desc;

full text from long ops - so you can do query plans.

select
   l.sid, 
   l.sofar, 
   l.totalwork, 
   l.start_time, 
   l.last_update_time, 
   t.sql_fulltext
from
   v$session_longops l       
left outer join
    v$sql s 
on 
   s.hash_value = l.sql_hash_value
and
   s.address = l.sql_address
and
   s.child_number = 0
left outer join  v$sqlarea t
on
   l.sql_hash_value = t.hash_value 
   order by TOTALWORK desc;


Then kill it, remember RDS on AWS does not let you run this – no matter who you are connected as:  Remember that if there are java processes in longops, basically you can kill them.  I would not touch runbatch longops -that is legitimate.  Quite often jdenet_k processes cannot really run long processes - you need to be a little bit careful here.

   alter system kill session '13993,34274'
Error report -
ORA-01031: insufficient privileges
01031. 00000 -  "insufficient privileges"
*Cause:    An attempt was made to perform a database operation without
           the necessary privileges.
*Action:   Ask your database administrator or designated security
           administrator to grant you the necessary privileges

You need to run their prooceure.

begin
    rdsadmin.rdsadmin_util.kill(
        sid    => 13993,
        serial => 34274);
end;

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