2026-03-12 21:01:38

2026-03-12 22:01:38 +01:00
parent 3bd1db26cc
commit 26296b6d6a
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--- a/tiddlywiki/SQL
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+-- SQL Profile  -- chargement à partir d'un plan d'exécution du Library Cache
+-- d'après le blog de Kerry Osborne ( http://kerryosborne.oracle-guy.com/2009/04/oracle-sql-profiles/ )
+-- et un exemple de Christian Antognini ( http://antognini.ch/top/ )
+
+DROP TABLE t1;
+
+CREATE TABLE t1 (id, col1, col2, pad)
+AS 
+SELECT rownum, CASE WHEN rownum>5000 THEN 5000 ELSE rownum END, rownum, lpad('*',100,'*')
+FROM dual
+CONNECT BY level <= 10000;
+
+CREATE INDEX t1_col1 ON t1 (col1);
+
+-- Calcul des statistiques avec des histogrammes automatiques
+BEGIN
+ dbms_stats.gather_table_stats(
+   ownname=>user, 
+   tabname=>'T1', 
+   cascade=>TRUE,
+   estimate_percent=>100,
+   method_opt=>'for all columns size skewonly',
+   no_invalidate=>FALSE);
+END;
+/
+
+-- Du moment que cursor_sharing n'est pas FORCE, des plans d'exécution differents sont
+-- générés en foction de la valeur du litteral
+-- On peut vérifier avec une 2ème session SYSDBA et les requêtes suivantes:
+-- SQL> select sid,serial#,SQL_ID,SQL_CHILD_NUMBER,PREV_SQL_ID,PREV_CHILD_NUMBER  from v$session where username=&username;
+-- SQL> select * from table(dbms_xplan.display_cursor(&SQL_ID,&SQL_CHILD_NUMBER,'typical'));
+-- probablement  &PREV_SQL_ID et &PREV_CHILD_NUMBER car les requêtes sont rapides
+
+
+-------------------------------------
+-- Dans une 2ème session AS SYSDBA =>
+-- nettoyage du Library Cache
+alter system flush shared_pool;
+-------------------------------------
+-- Session applicative => 
+-- FULL SCAN
+select * from t1 where col1=5000;
+
+-- Dans une 2ème session AS SYSDBA =>
+-- 1er snapshoot AWR
+execute dbms_workload_repository.CREATE_SNAPSHOT;
+
+
+-- Session applicative => 
+-- ACCES PAR INDEX
+select * from t1 where col1=128;
+
+
+-- Dans une 2ème session AS SYSDBA =>
+-- 2ème snapshoot AWR
+execute dbms_workload_repository.CREATE_SNAPSHOT;
+
+------------------------------------------------------
+-- SESSION 2 as SYSDBA
+-- on récupère le SQL_ID, ainsi que le Plan hash value du SQL qui fait en FULL 
+
+set pages 999
+set line 200
+col SQL_TEXT for a70 wrap
+
+select dbid,sql_id,sql_text from DBA_HIST_SQLTEXT where SQL_TEXT like '%select * from t1 where col1=%';
+
+select * from table(dbms_xplan.display_awr('b9tum9b80gsjx')); -- FULL
+
+-- Nous alons créer un SQL Profile qui utilise ce denier plan d'exécution (FULL)
+-- les valeurs d'entrée:
+-- sql_id = 'b9tum9b80gsjx' / plan_hash_value=3617692013 / category => 'SQLPROF_CAT_01' / name => 'SQLPROF_SQLPROF_02' / force_match => true
+
+/* Randolf Giest */
+-- create sql profile from awr
+-- sql_id plan_hash_valeu category force_matching
+declare
+  ar_profile_hints sys.sqlprof_attr;
+  cl_sql_text clob;
+begin
+  select
+  extractvalue(value(d), '/hint') as outline_hints
+  bulk collect
+  into
+  ar_profile_hints
+  from
+  xmltable('/*/outline_data/hint'
+  passing (
+  select
+  xmltype(other_xml) as xmlval
+  from
+  dba_hist_sql_plan
+  where
+  sql_id = 'b9tum9b80gsjx'
+  and plan_hash_value = 3617692013
+  and other_xml is not null
+  )
+  ) d;
+  
+  select
+  sql_text
+  into
+  cl_sql_text
+  from
+  dba_hist_sqltext
+  where
+  sql_id = 'b9tum9b80gsjx';
+  
+  dbms_sqltune.import_sql_profile(
+  sql_text => cl_sql_text
+  , profile => ar_profile_hints
+  , category => 'SQLPROF_CAT_01'
+  , name => 'SQLPROF_SQLPROF_02'
+  -- use force_match => true
+  -- to use CURSOR_SHARING=SIMILAR
+  -- behaviour, i.e. match even with
+  -- differing literals
+  , force_match => true
+  );
+end;
+/
+
+-- On vérifie que le SQL Plan a été créé
+-- normallement c'est afficher dans la note
+
+set line 128
+col sql_text for a40 wrap
+select name,category,sql_text,status,force_matching from DBA_SQL_PROFILES;
+
+------------------------------------------------------
+-- On reviens dans la première session (celle applicative)
+-- on change la catègorie courante de SQL Tune
+-- on vérifie que le pla d'exécution est bien celui du SQL Profile
+
+alter session set sqltune_category='SQLPROF_CAT_01';
+
+explain plan for select * from t1 where col1=5000;
+select * from table(dbms_xplan.display);
+
+explain plan for select * from t1 where col1=1200;
+select * from table(dbms_xplan.display);