SQL Access Advisor的使用

环境:

OS:Red Hat Linux As 5

DB:10.2.0.4

 

SQL Access Advisor是伴随着10G出现的一个优化工具,提供对表分区,物化视图,索引,物化视图日志优化建议.下边通过对单个SQL的执行,查看Oracle给出的建议.

 

1.建表并生成测试数据

SQL> connect scott/scott
Connected.
SQL> drop table tb_test;
SQL> create table tb_test(id number not null,name varchar2(30));
Table created.
SQL> create index idx_tb_test on tb_test(id);
Index created.
SQL> declare
begin
  for i in 1 .. 100000 loop
    insert into tb_test values (i, 'test');
    commit;
  end loop;
end;

 

2.分析表

connect / as sysdba

begin
  dbms_stats.gather_table_stats(ownname => 'SCOTT', tabname => 'TB_TEST',cascade => true);
end;

3.使用dbms_advisor.quick_tune生成优化建议

connect / as sysdba

declare
  l_task_name VARCHAR2(255);
  l_sql_stmt  VARCHAR2(4000);
begin
  l_sql_stmt  := 'select /*+ full(t) */ * from scott.tb_test t where t.id = :1';
  l_task_name := 'MY_FULL_ACCESS_TEST';
  DBMS_ADVISOR.QUICK_TUNE(DBMS_ADVISOR.SQLACCESS_ADVISOR,
                          l_task_name,
                          l_sql_stmt);
  exception when others then dbms_output.put_line(sqlerrm);                    
end;

我们这里造一个走全表扫描的索引,很明显走索引才是正确的,这里的目的主要是看oracle会给出什么样的建议.

 

4.查看优化建议

SQL> set serveroutput on;
SQL> set long 999999999;
SQL> begin
       show_recm('MY_FULL_ACCESS_TEST');
     end;

=========================================
Task_name = MY_FULL_ACCESS_TEST
Action ID: 1
Command : RETAIN INDEX
Attr1 (name)      : "SCOTT"."IDX_TB_TEST_N1"
Attr2 (tablespace):
Attr3             : "SCOTT"."TB_TEST"
Attr4             : BTREE
Attr5             :
----------------------------------------
=========END RECOMMENDATIONS============

PL/SQL procedure successfully completed.

 

从以上输出可以看出oracle给出的建议是走索引.

 

show_recm过程如下:

CREATE OR REPLACE PROCEDURE show_recm (in_task_name IN VARCHAR2) IS
CURSOR curs IS
  SELECT DISTINCT action_id, command, attr1, attr2, attr3, attr4
  FROM dba_advisor_actions
  WHERE task_name = in_task_name
  ORDER BY action_id;
  v_action        number;
  v_command     VARCHAR2(32);
  v_attr1       VARCHAR2(4000);
  v_attr2       VARCHAR2(4000);
  v_attr3       VARCHAR2(4000);
  v_attr4       VARCHAR2(4000);
  v_attr5       VARCHAR2(4000);
BEGIN
  OPEN curs;
  DBMS_OUTPUT.PUT_LINE('=========================================');
  DBMS_OUTPUT.PUT_LINE('Task_name = ' || in_task_name);
  LOOP
     FETCH curs INTO
       v_action, v_command, v_attr1, v_attr2, v_attr3, v_attr4 ;
   EXIT when curs%NOTFOUND;
   DBMS_OUTPUT.PUT_LINE('Action ID: ' || v_action);
   DBMS_OUTPUT.PUT_LINE('Command : ' || v_command);
   DBMS_OUTPUT.PUT_LINE('Attr1 (name)      : ' || SUBSTR(v_attr1,1,30));
   DBMS_OUTPUT.PUT_LINE('Attr2 (tablespace): ' || SUBSTR(v_attr2,1,30));
   DBMS_OUTPUT.PUT_LINE('Attr3             : ' || SUBSTR(v_attr3,1,30));
   DBMS_OUTPUT.PUT_LINE('Attr4             : ' || v_attr4);
   DBMS_OUTPUT.PUT_LINE('Attr5             : ' || v_attr5);
   DBMS_OUTPUT.PUT_LINE('----------------------------------------');
   END LOOP;
   CLOSE curs;
   DBMS_OUTPUT.PUT_LINE('=========END RECOMMENDATIONS============');
END show_recm;

 

-- The End --