Exploitation, Métrologie, SQL, Support Niveau 2, Support Niveau 3

Incidence du statistics level

La variable statistics level permet des stocker des statistiques dans certaines vues.

La requête suivante permet de voir quelle vue est impactée, à quel niveau de statistique et si le calcul de la statistique peut être modifié au niveau session

select decode(ACTIVATION_LEVEL,1,'Typical','All') "A Level"
  , Name
  , decode(SESSION_CHANGEABLE,1,'Ok',' -') "Modif"
  , decode(SESSION_STATUS,1,'On',' -') "Sess"
  , decode(SYSTEM_STATUS,1,'On',' -') "Sys"
  , VIEW_NAME
from x$prmsltyx
order by ACTIVATION_LEVEL
/

En 11gR2 on obtient 

A Level NAME                                                             Mo Se Sy VIEW_NAME
------- ---------------------------------------------------------------- -- -- -- -------------------------
Typical Buffer Cache Advice                                               - On On V$DB_CACHE_ADVICE
Typical V$IOSTAT_* statistics                                             - On On
Typical Timed Statistics                                                 Ok On On
Typical MTTR Advice                                                       - On On V$MTTR_TARGET_ADVICE
Typical Adaptive Thresholds Enabled                                       - On On
Typical Segment Level Statistics                                          - On On V$SEGSTAT
Typical PGA Advice                                                        - On On V$PGA_TARGET_ADVICE
Typical Shared Pool Advice                                                - On On V$SHARED_POOL_ADVICE
Typical Modification Monitoring                                           - On On
Typical Longops Statistics                                                - On On V$SESSION_LONGOPS
Typical Bind Data Capture                                                 - On On V$SQL_BIND_CAPTURE
Typical Ultrafast Latch Statistics                                        - On On
Typical Threshold-based Alerts                                            - On On
Typical Global Cache Statistics                                           - On On
Typical Active Session History                                            - On On V$ACTIVE_SESSION_HISTORY
Typical Undo Advisor, Alerts and Fast Ramp up                             - On On V$UNDOSTAT
Typical Streams Pool Advice                                               - On On V$STREAMS_POOL_ADVICE
Typical Time Model Events                                                Ok On On V$SESS_TIME_MODEL
Typical Plan Execution Sampling                                          Ok On On V$ACTIVE_SESSION_HISTORY
Typical Automated Maintenance Tasks                                       - On On
Typical SQL Monitoring                                                   Ok On On V$SQL_MONITORING
All     Plan Execution Statistics                                        Ok  -  - V$SQL_PLAN_STATISTICS
All     Timed OS Statistics                                              Ok  -  -

En 10g on obtient 

A Level NAME                                     Mo Se Sy VIEW_NAME
------- ---------------------------------------- -- -- -- ------------------------------
Typical Buffer Cache Advice                       - On On V$DB_CACHE_ADVICE
Typical Streams Pool Advice                       - On On V$STREAMS_POOL_ADVICE
Typical Timed Statistics                         Ok On On
Typical MTTR Advice                               - On On V$MTTR_TARGET_ADVICE
Typical Undo Advisor, Alerts and Fast Ramp up     - On On V$UNDOSTAT
Typical Segment Level Statistics                  - On On V$SEGSTAT
Typical PGA Advice                                - On On V$PGA_TARGET_ADVICE
Typical Shared Pool Advice                        - On On V$SHARED_POOL_ADVICE
Typical Modification Monitoring                   - On On
Typical Longops Statistics                        - On On V$SESSION_LONGOPS
Typical Bind Data Capture                         - On On V$SQL_BIND_CAPTURE
Typical Ultrafast Latch Statistics                - On On
Typical Threshold-based Alerts                    - On On
Typical Global Cache Statistics                   - On On
Typical Active Session History                    - On On V$ACTIVE_SESSION_HISTORY
All     Plan Execution Statistics                Ok  -  - V$SQL_PLAN_STATISTICS
All     Timed OS Statistics                      Ok  -  -

En 9i on obtient 

A Level NAME                           Mo Se Sy VIEW_NAME
------- ------------------------------ -- -- -- ------------------------------
Typical Buffer Cache Advice             - On On V$DB_CACHE_ADVICE
Typical MTTR Advice                     - On On V$MTTR_TARGET_ADVICE
Typical Timed Statistics               Ok On On
Typical PGA Advice                      - On On V$PGA_TARGET_ADVICE
Typical Shared Pool Advice              - On On V$SHARED_POOL_ADVICE
Typical Segment Level Statistics        - On On V$SEGSTAT
All     Timed OS Statistics            Ok  -  -
All     Plan Execution Statistics      Ok  -  - V$SQL_PLAN_STATISTICS
Exploitation, Support Niveau 3, Tuning

Afficher la liste des “fix control” passés sur une base

Les fix control sont apportés par les patchs / patchsets / patchsets updates et influent sur le comportement de l’optimiseur. La table x$qksbgsys les liste et donne leur description succincte

La requête suivante liste les bugs, ce qu’ils font et la version à partir de laquelle ils ont étés introduits

select BUGNO_QKSBGSYROW
  , DESC_QKSBGSYROW
  , OFE_QKSBGSYROW
  , EVENT_QKSBGSYROW
from x$qksbgsys
/

BUGNO_QKSBGSYROW DESC_QKSBGSYROW                                                  OFE_QKSBGSYROW            EVENT_QKSBGSYROW
---------------- ---------------------------------------------------------------- ------------------------- ----------------
        4611850 do not clobber predicate during first-k row estimate phase       10.2.0.2                                 0
        4663804 use smallest table as first table in join card. initial ordering 10.2.0.2                                 0
        4663698 for cached NL table set tab_cost_io to zero                      10.2.0.2                                 0
[...]

La requete suivante sur la table x$qksbgses est équivalente

select distinct BUGNO_QKSBGSEROW
   , DESC_QKSBGSEROW
   , OFE_QKSBGSEROW
   , EVENT_QKSBGSEROW
from x$qksbgses
/

Il est possible de désactiver un des correctifs par hint :

select /*+ OPT_PARAM('_fix_control' '9195582:0') */ * from dual ;

Depuis quelques version les vues V$SYS_FIX_CONTROL et V$SESSION_FIX_CONTROL permettent de voir ces données plus facilement

desc V$SESSION_FIX_CONTROL
 Name                             Null?    Type
 -------------------------------- -------- ----------------------
 SESSION_ID                                NUMBER
 BUGNO                                     NUMBER
 VALUE                                     NUMBER
 SQL_FEATURE                               VARCHAR2(64)
 DESCRIPTION                               VARCHAR2(64)
 OPTIMIZER_FEATURE_ENABLE                  VARCHAR2(25)
 EVENT                                     NUMBER
 IS_DEFAULT                                NUMBER

desc V$SYSTEM_FIX_CONTROL
 Name                             Null?    Type
 -------------------------------- -------- ----------------------
 BUGNO                                     NUMBER
 VALUE                                     NUMBER
 SQL_FEATURE                               VARCHAR2(64)
 DESCRIPTION                               VARCHAR2(64)
 OPTIMIZER_FEATURE_ENABLE                  VARCHAR2(25)
 EVENT                                     NUMBER
 IS_DEFAULT                                NUMBER
Développement, Exploitation, SQL, Support Niveau 3

Lister les tables X$ d’une version Oracle

Ce petit script PERL permet de lister les tables “X$” du moteur … Ce qui ne dit pas ce qu’elles font

#!/usr/bin/perl -w

use strict;

#open O, ($ORACLE_HOME."/bin/oracle");
open O, ("/logiciels/oracle/ora_10.2.0/bin/oracle");
open F, (">x");

my $l;
my $p = ' ' x 40;
my %x;

while (read (O,$l,10000)) {
  $l = $p.$l;

  foreach ($l =~ /(x$w{3,})/g) {
   $x{$_}++;
  }

  $p = substr ($l,-40);
}

foreach (sort keys %x) {
  print F "$_n";
}

Ce script provient du site http://www.adp-gmbh.ch

On peut trouver certaines explications sur le contenu des tables “X$” sur freeshell, sur le site BC Oracle Training ou en bien d’autres endroits 😉

La version 10 d’oracle en liste quelques 350 par exemple la table x$kwddef liste l’ensemble des mots clés du SQL, la requête suivante permet donc de les lister :

select KEYWORD from x$kwddef
order by KEYWORD
/
Développement

Citation

“The programmers didn’t like the idea at all because it deprived them of the intellectual excitement of not quite understanding what they were doing. They like the challenge of chasing the bugs.”

E. Dijkstra (Prix Turing)

Support Niveau 3

vipca -silent

Créer les adresses vip en utilisant vipca en mode silencieux :

En étant connecté root :

vipca -silent -nodelist rac01,rac02 -nodevips 'rac01/rac01-vip/255.255.255.0/ce1,rac02/rac02-vip/255.255.255.0/ce1'

Gérer le failover des VIP :

crs_stat -p ora.rac01.vip > /var/tmp/ora.rac01.vip.cap
crs_stat -p ora.rac02.vip > /var/tmp/ora.rac02.vip.cap

changer les lignes

HOSTING_MEMBERS=rac01

en

HOSTING_MEMBERS=rac01 rac02

crs_register ora.rac01.vip -dir /var/tmp -u
crs_register ora.rac02.vip -dir /var/tmp -u
Bonnes pratiques, Développement, Exploitation, Métrologie, PL/SQL, SQL, Support Niveau 2, Tuning

Générer des rapports statspack

Petite procédure pour générer un nombre important de rapports statspack.

SET SERVEROUTPUT OFF
set feedback off

var delta number;
var date_fin varchar2(20);
begin
:delta:=&1;
--  :date_fin:=&2;
end;
/

create or replace procedure dba_all_reports( delta in number
                                         , fin in varchar default to_char(sysdate, 'YYYYMMDDHH24MI') ) as
begin
for i in (select snap_id
        , snap_next
        , to_char(snap_time, 'MMDD_HH24MI') rpt_name
        , instance_name
      from (select s.SNAP_ID
              , lead(s.SNAP_ID,1) over (order by s.SNAP_ID) SNAP_NEXT
              , s.STARTUP_TIME
              , lead(s.STARTUP_TIME, 1) over (order by s.SNAP_ID) STARTUP_NEXT
              , s.SNAP_TIME
              , i.INSTANCE_NAME
            from stats$snapshot s, v$instance i)
      where SNAP_NEXT=SNAP_ID+1
      and STARTUP_TIME=STARTUP_NEXT
      and snap_time between to_date(fin,'YYYYMMDDHH24MI')-delta and to_date(fin,'YYYYMMDDHH24MI') )
loop
DBMS_OUTPUT.ENABLE (32000);
dbms_output.put_line ('define begin_snap='||i.snap_id);
dbms_output.put_line ('define end_snap='||i.snap_next);
dbms_output.put_line ('define report_name='||i.instance_name||'_'||i.rpt_name);
dbms_output.put_line ('@?/rdbms/admin/spreport.sql');
end loop;
end;
/

SET SERVEROUTPUT ON
spool reports.sql
-- execute dba_all_reports(:delta, :date_fin)
execute dba_all_reports(:delta)
spool off

@reports.sql

drop procedure dba_all_reports;

Les rapports ainsi générés sont nommés <ORACLE_SID>_<MOIS><JOUR>_<HEURE><MINUTES>.lst

On peut décommenter les lignes

--  :date_fin:=&2;

et

-- execute dba_all_reports(:delta, :date_fin)

et supprimer la ligne

execute

dba_all_reports(:delta)

de manière à générer des rapports anciens.

Exploitation, Métrologie, SQL

Les requêtes consommatrices

Bon un petit peu de technique histoire d’aider ma mémoire avec une requête bien sympatoche histoire de tracer la consommation SQL d’une base


select sql_id, dsk_rd, tot_rd, to_char((dsk_rd/tot_rd)*100,'999D99') || ' %' "PCT RDS"
 from (select distinct 1 c1
    , sql_id
    , sum(disk_reads_DELTA) over (partition by sql_id) dsk_rd 
    , sum(disk_reads_delta) over (partition by 1) tot_rd
   from DBA_HIST_SQLSTAT
  where nvl(disk_reads_DELTA,0) > 0
  order by 3 desc)
where rownum < 11
and tot_rd > 0

Au résultat on obtient un petit tableau de ce type


SQL_ID            DSK_RD     TOT_RD PCT RDS
------------- ---------- ---------- ---------
b7jn4mf49n569       6234      21773   28,63 %
gfjvxb25b773h       1990      21773    9,14 %
c7sn076yz7030        939      21773    4,31 %
cvn54b7yz0s8u        849      21773    3,90 %
cfz686a6qp0kg        808      21773    3,71 %
c2p32r5mzv8hb        709      21773    3,26 %
7q2wnyku8mfv0        630      21773    2,89 %
b3ys9bs1v9cch        547      21773    2,51 %
39m4sx9k63ba2        437      21773    2,01 %
02577v815yp77        412      21773    1,89 %

Bien cryptique ? Certes mais utile dans le cadre d’un audit de perf. (à partir de la version 10 d’oracle).

Pour tracer une évolution au travers des snapshots AWR (Automatic Workload Reppository) on pourra modifier de cette manière :


break on snap_id skip 1

select  SNAP_ID
        , SQL_ID
        , disk_reads_DELTA
        , to_char((disk_reads_delta/tot)*100,'999D99') || ' %' "PCT RDS"
from (select SNAP_ID
    , SQL_ID
    , disk_reads_DELTA
    , dense_rank() over ( partition by snap_id order by disk_reads_DELTA desc, sql_id asc) rk
    , sum(disk_reads_DELTA) over ( partition by snap_id) tot
  from DBA_HIST_SQLSTAT
  where nvl(disk_reads_DELTA,0) > 0)
where rk < 11 
and tot > 0
order by snap_id, rk

La remontée est alors du type :


   SNAP_ID SQL_ID        DISK_READS_DELTA PCT RDS
---------- ------------- ---------------- ---------
       273 b3ys9bs1v9cch               18   42,86 %
           4ng4xn7jw3dbb                8   19,05 %
           0a1k5zuh04f38                7   16,67 %
           96g93hntrzjtr                3    7,14 %
           bunssq950snhf                2    4,76 %
           as3uq6ggb3gx6                1    2,38 %
           f4fvybbfcbk5y                1    2,38 %
           gc7b0drtzbyc6                1    2,38 %
           8sd37ztuwkyyc                1    2,38 %

       276 dnwpm0gdccrph                6  100,00 %

   SNAP_ID SQL_ID        DISK_READS_DELTA PCT RDS
---------- ------------- ---------------- ---------

       287 g337099aatnuj                1  100,00 %

       289 8yh7x8qkgswu2                2  100,00 %

       297 b3ys9bs1v9cch               16   42,11 %
           5rxbazwmcdfaz                7   18,42 %
           70vs1d7ywk5m0                7   18,42 %
           4ng4xn7jw3dbb                3    7,89 %
           96g93hntrzjtr                3    7,89 %
           as3uq6ggb3gx6                1    2,63 %

   SNAP_ID SQL_ID        DISK_READS_DELTA PCT RDS
---------- ------------- ---------------- ---------
       297 gc7b0drtzbyc6                1    2,63 %