oracle 11g caracteristicas poco documentadas 3 en 1
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Serie Underground Por Ronald Vargas, Oracle ACE Oracledbacr.blogspot.com
Indices virtuales
Oracledbacr.blogspot.com @rovaque
Indices virtuales
• El proceso de afinamiento de instrucciones SQL, requiere que de manera alterna, podamos definir estrategias de indexación, para observar su efecto en los planes de ejecución.
• Crear índices adicionales, no es el problema.
Indices virtuales
• El problema es, que crear índices extras sobre tablas grandes, puede tomar un monto considerado de tiempo y espacio en disco.
• Adicionalmente, los índices creados pueden ser utilizados por otras sesiones de usuarios y podría afectar el rendimiento en otras partes de la aplicación.
• Esto puede ser problemático cuando estamos intentando identificar el problema en un sistema en producción.
Indices virtuales
– En contraste a los índices convencionales, los índices virtuales no están asociados a un segmento, el tiempo de creación y el espacio asociado en disco es irrelevante.
– Adicionalmente, no pueden ser vistos por otras sesiones, por tanto, no se ve afectado el normal funcionamiento del sistema.
– Este clase muestra de manera sencilla como utilizarlos y las consideraciones que debemos tener en cuenta.
Indices virtuales
SQL> desc movto_h Name Null? Type ----------------------------------------- -------- -------------- NO_CIA NOT NULL VARCHAR2(2)
CENTRO NOT NULL VARCHAR2(2) TIPO_DOC NOT NULL VARCHAR2(2) PERIODO NOT NULL VARCHAR2(4)
RUTA NOT NULL VARCHAR2(4) NO_DOCU NOT NULL VARCHAR2(12) FECHA NOT NULL DATE NO_FISICO VARCHAR2(12)
SERIE_FISICO VARCHAR2(15) ... FECHA_APLICACION DATE
TSTAMP DATE NO_TRASLADO VARCHAR2(12)
SQL> select count(*) from movto_h; COUNT(*) ---------- 6445961
Indices virtuales
Indices virtuales
SQL> create index v_movto_h_nofisico on movto_h(no_fisico) nosegment; Index created. SQL> explain plan for 2 select count(distinct no_fisico) from movto_h; Explained.
Indices virtuales
SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------ Plan hash value: 891170817 ------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 7 | 21381 (3)| 00:04:17 | | 1 | SORT GROUP BY | | 1 | 7 | | | | 2 | TABLE ACCESS FULL| movto_h | 6445K| 43M| 21381 (3)| 00:04:17 | ------------------------------------------------------------------------------ 9 rows selected.
Indices virtuales
SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained. SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------- Plan hash value: 891170817 ------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 7 | 21547 (3)| 00:04:19 | | 1 | SORT GROUP BY | | 1 | 7 | | | |* 2 | TABLE ACCESS FULL| movto_h | 322K| 2203K| 21547 (3)| 00:04:19 | ------------------------------------------------------------------------------ Predicate Information (identified by operation id): PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------ 2 - filter(TO_NUMBER("NO_FISICO")<10000) 14 rows selected.
SQL> create index v_movto_h_nofisico2 on movto_h(to_number(no_fisico)) nosegment; Index created. SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained.
Indices virtuales
Indices virtuales
SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------- Plan hash value: 891170817 ------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 7 | 21547 (3)| 00:04:19 | | 1 | SORT GROUP BY | | 1 | 7 | | | |* 2 | TABLE ACCESS FULL| movto_h | 322K| 2203K| 21547 (3)| 00:04:19 | ------------------------------------------------------------------------------ Predicate Information (identified by operation id): PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------- 2 - filter(TO_NUMBER("NO_FISICO")<10000) 14 rows selected.
Indices virtuales
SQL> SQL> alter session set "_use_nosegment_indexes"=TRUE; Session altered. SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained.
Indices virtuales SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------- Plan hash value: 2481667387 -------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 7 | 7 (0)| 00:00:01 | | 1 | SORT GROUP BY | | 1 | 7 | | | |* 2 | INDEX FAST FULL SCAN| V_movto_h_NOFISICO | 322K| 2203K| 7 (0)| 00:00:01 | -------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------- 2 - filter(TO_NUMBER("NO_FISICO")<10000) 14 rows selected.
Indices virtuales
SQL> SELECT index_owner, index_name 2 FROM dba_ind_columns 3 WHERE index_name NOT LIKE 'BIN$%' 4 MINUS 5 SELECT owner, index_name 6 FROM dba_indexes; INDEX_OWNER INDEX_NAME ------------------------------ ------------------------------ PRUEBAS21 V_movto_h_NOFISICO PRUEBAS21 V_movto_h_NOFISICO2 PRUEBAS21 V_ARINMN
Indices virtuales
SQL> drop index v_movto_h_nofisico; Index dropped. SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained.
Indices virtuales SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------- Plan hash value: 11771441 -------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 7 | 10 (0)| 00:00:01 | | 1 | SORT GROUP BY | | 1 | 7 | | | | 2 | TABLE ACCESS BY INDEX ROWID| movto_h | 322K| 2203K| 10 (0)| 00:00:01 | |* 3 | INDEX RANGE SCAN | V_movto_h_NOFISICO2 | 58014 | | 2 (0)| 00:00:01 | -------------------------------------------------------------------------------------- PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - access(TO_NUMBER("NO_FISICO")<10000) 15 rows selected.
Indices virtuales SQL> select count(*) from movto_h; COUNT(*) ---------- 6445961 drop index v_movto_h_nofisico2; create index v_movto_h_nofisico2 on movto_h(to_number(no_fisico)) nosegment; drop index v_movto_h_nofisico2; create index v_movto_h_nofisico2 on movto_h(to_number(no_fisico)); SQL> drop index v_movto_h_nofisico2; Index dropped.
Indices virtuales SQL> SQL> set timing on; SQL> SQL> create index v_movto_h_nofisico2 on movto_h(to_number(no_fisico)) nosegment; Index created. Elapsed: 00:00:00.03 SQL> drop index v_movto_h_nofisico2; Index dropped. Elapsed: 00:00:00.02
Indices virtuales SQL> create index v_movto_h_nofisico2 on movto_h(to_number(no_fisico)); Index created. Elapsed: 00:01:09.56 SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained. Elapsed: 00:00:00.01
Indices virtuales SQL> select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------- Plan hash value: 891170817 ------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 7 | 21547 (3)| 00:04:19 | | 1 | SORT GROUP BY | | 1 | 7 | | | |* 2 | TABLE ACCESS FULL| movto_h | 322K| 2203K| 21547 (3)| 00:04:19 | ------------------------------------------------------------------------------ Predicate Information (identified by operation id): PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------ 2 - filter(TO_NUMBER("NO_FISICO")<10000) 14 rows selected.
Indices virtuales
SQL> alter session set "_use_nosegment_indexes"=FALSE; Session altered. Elapsed: 00:00:00.01 SQL> explain plan for 2 select count(distinct no_fisico) from movto_h where no_fisico < 10000; Explained. Elapsed: 00:00:00.01 SQL> select * from table(dbms_xplan.display);
Indices virtuales PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------- Plan hash value: 891170817 ------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 7 | 21547 (3)| 00:04:19 | | 1 | SORT GROUP BY | | 1 | 7 | | | |* 2 | TABLE ACCESS FULL| movto_h | 322K| 2203K| 21547 (3)| 00:04:19 | ------------------------------------------------------------------------------ Predicate Information (identified by operation id): PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------- 2 - filter(TO_NUMBER("NO_FISICO")<10000) 14 rows selected.
Indices virtuales
Indices virtuales Calculando estadísticas al índice virtual SQL> drop index V_movto_h_NOFISICO2; Index dropped. SQL> create index v_movto_h_nofisico2 on MOVTO_H(to_number(no_fisico)) nosegment; Index created. SQL> execute dbms_stats.gather_index_stats('PRUEBAS21','V_MOVTO_H_NOFISICO2'); PL/SQL procedure successfully completed.
Indices virtuales
SQL> alter session set "_use_nosegment_indexes"=TRUE; Session altered. SQL> explain plan for 2 select count(distinct no_fisico) from MOVTO_H where no_fisico < 10000; Explained. SQL> set linesize 1000 SQL> select * from table(dbms_xplan.display);
Indices virtuales PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------------------------- Plan hash value: 1788350122 ---------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 7 | 30 (0)| 00:00:01 | | 1 | SORT GROUP BY | | 1 | 7 | | | | 2 | TABLE ACCESS BY INDEX ROWID| MOVTO_H | 218K| 1495K| 30 (0)| 00:00:01 | |* 3 | INDEX RANGE SCAN | V_MOVTO_H_NOFISICO2 | 218K| | 2 (0)| 00:00:01 | ---------------------------------------------------------------------------------------------------- PLAN_TABLE_OUTPUT ----------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 3 - access(TO_NUMBER("NO_FISICO")<10000)
Indices virtuales
El optimizador de Oracle 10g y superiores trabaja basado en optimización por COSTO. RBO no esta soportado en Oracle11g
Columnas Virtuales
Fórmula / columnas calculadas - sobre la base de datos Restricciones adicionales - sobre la base de datos Nueva categoría para la partición - sobre la base de datos Integridad creativa de referencia - en la base de datos
Sin columnas virtuales- inconvenientes
Triggers - caros Vistas- a veces se olvidan Re-diseño – Mucho trabajo duro!
Columnas Virtuales
Columnas Virtuales SQL> show user USER is "DEMO_LAB" SQL> desc employees Name Null? Type ----------------------------------------- -------- ---------------------------- EMPLOYEE_ID NUMBER(6) FIRST_NAME VARCHAR2(20) LAST_NAME NOT NULL VARCHAR2(25) EMAIL NOT NULL VARCHAR2(25) PHONE_NUMBER VARCHAR2(20) HIRE_DATE NOT NULL DATE JOB_ID NOT NULL VARCHAR2(10) SALARY NUMBER(8,2) COMMISSION_PCT NUMBER(2,2) MANAGER_ID NUMBER(6) DEPARTMENT_ID NUMBER(4) SQL> SQL>
Columnas Virtuales
1 insert into employees(employee_id, first_name, last_name, email, hire_date, job_id) 2* values (&empleado_id, '&nombre', '&apellido', '&email', to_date('&nacimiento','dd-mm-yyyy'), &id_empleado) SQL> / Enter value for empleado_id: 1 Enter value for nombre: Ronald Enter value for apellido: Vargas Enter value for email: [email protected] Enter value for nacimiento: 03-09-1968 Enter value for id_empleado: 10 old 2: values (&empleado_id, '&nombre', '&apellido', '&email', to_date('&nacimiento','dd-mm-yyyy'), &id_empleado) new 2: values (1, 'Ronald', 'Vargas', '[email protected]', to_date('03-09-1968','dd-mm-yyyy'), 10) 1 row created. SQL> commit;
Columnas Virtuales
SQL> select * from employees; EMPLOYEE_ID FIRST_NAME LAST_NAME ----------- -------------------- ------------------------- EMAIL PHONE_NUMBER HIRE_DATE JOB_ID SALARY ------------------------- -------------------- --------- ---------- ---------- COMMISSION_PCT MANAGER_ID DEPARTMENT_ID -------------- ---------- ------------- 1 Ronald Vargas [email protected] 03-SEP-68 10
SQL> update employees set salary=200000; 1 row updated. SQL> commit; Commit complete. SQL> select * from employees; EMPLOYEE_ID FIRST_NAME LAST_NAME ----------- -------------------- ------------------------- EMAIL PHONE_NUMBER HIRE_DATE JOB_ID SALARY ------------------------- -------------------- --------- ---------- ---------- COMMISSION_PCT MANAGER_ID DEPARTMENT_ID -------------- ---------- ------------- 1 Ronald Vargas [email protected] 03-SEP-68 10 200000
Columnas Virtuales
SQL> alter table employees add IMPUESTO_RENTA as (nvl(salary,0)*0.10); Table altered. SQL> desc employees Name Null? Type ----------------------------------------- -------- ---------------------------- EMPLOYEE_ID NUMBER(6) FIRST_NAME VARCHAR2(20) LAST_NAME NOT NULL VARCHAR2(25) EMAIL NOT NULL VARCHAR2(25) PHONE_NUMBER VARCHAR2(20) HIRE_DATE NOT NULL DATE JOB_ID NOT NULL VARCHAR2(10) SALARY NUMBER(8,2) COMMISSION_PCT NUMBER(2,2) MANAGER_ID NUMBER(6) DEPARTMENT_ID NUMBER(4) IMPUESTO_RENTA NUMBER
Columnas Virtuales
SQL> set linesize 200 SQL> select employee_id, first_name, last_name, salary, impuesto_renta from employees; EMPLOYEE_ID FIRST_NAME LAST_NAME SALARY IMPUESTO_RENTA ----------- -------------------- ------------------------- ---------- -------------- 1 Ronald Vargas 200000 20000
SQL> update employees set salary=400000 where employee_id=1; 1 row updated. SQL> commit; Commit complete.
Columnas Virtuales
Columnas Virtuales
SQL> select employee_id, first_name, last_name, salary, impuesto_renta from employees; EMPLOYEE_ID FIRST_NAME LAST_NAME SALARY IMPUESTO_RENTA ----------- -------------------- ------------------------- ---------- -------------- 1 Ronald Vargas 400000 40000 SQL>
SQL> alter table employees add email_sugerido as (substr(first_name,1,1)||'.'||last_name||'@'||'laboratorio.com'); Table altered. SQL> / FIRST_NAME LAST_NAME SALARY IMPUESTO_RENTA EMAIL_SUGERIDO -------------------- ------------------------- ---------- -------------- ----------------------------- Ronald Vargas 400000 40000 [email protected]
SQL> update employees set first_name='Manuel' where impuesto_renta=40000; 1 row updated. SQL> commit; Commit complete.
Columnas Virtuales
Columnas Virtuales SQL> select first_name, last_name, salary, impuesto_renta, email_sugerido from employees; FIRST_NAME LAST_NAME SALARY IMPUESTO_RENTA EMAIL_SUGERIDO -------------------- ------------------------- ---------- -------------- -------------------------- Manuel Vargas 400000 40000 [email protected] SQL> desc employees Name Null? Type ----------------------------------------- -------- ---------------------------- EMPLOYEE_ID NUMBER(6) FIRST_NAME VARCHAR2(20) LAST_NAME NOT NULL VARCHAR2(25) EMAIL NOT NULL VARCHAR2(25) PHONE_NUMBER VARCHAR2(20) HIRE_DATE NOT NULL DATE JOB_ID NOT NULL VARCHAR2(10) SALARY NUMBER(8,2) COMMISSION_PCT NUMBER(2,2) MANAGER_ID NUMBER(6) DEPARTMENT_ID NUMBER(4) IMPUESTO_RENTA NUMBER EMAIL_SUGERIDO VARCHAR2(41)
Crear un dblink sin tocar el tnsnames
system@TEST11> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production PL/SQL Release 11.1.0.7.0 - Production CORE 11.1.0.7.0 Production TNS for Linux: Version 11.1.0.7.0 - Production NLSRTL Version 11.1.0.7.0 - Production 5 rows selected. system@TEST11> select * from dba_db_links; no rows selected
Crear un dblink sin tocar el tnsnames system@TEST1 1> create database link testlink_db2 2 connect to system identified by oracle 3 using 4 '(DESCRIPTION= 5 (ADDRESS= 6 (PROTOCOL=TCP) 7 (HOST=10.2.10.18) 8 (PORT=1525)) 9 (CONNECT_DATA= 10 (SID=test10)))' 11 / Database link created.
Crear un dblink sin tocar el tnsnames
system@TEST11> select * from v$version@testlink_db2; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Prod PL/SQL Release 10.2.0.4.0 - Production CORE 10.2.0.4.0 Production TNS for Linux: Version 10.2.0.4.0 - Production NLSRTL Version 10.2.0.4.0 - Production 5 rows selected. -- cleanout system@TEST11> drop database link testlink_db2; Database link dropped.