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SQL调优顾问 SQL Tuning Advisor的使用案例：
1.构建测试表T
SQL> conn zjy/zjy Connected. SQL> create table t as select * from dba_objects; Table created. SQL> select count(*) from t; COUNT(*) ---------- 653500
2.对“select owner, object_id, object_name from t where object_id=200000”这个sql定义调整任务：
SQL> declare 2 tune_task_name varchar2(30); 3 bad_sql_stmt clob; 4 begin 5 bad_sql_stmt := ‘select owner, object_id, object_name from t where object_id=200000‘; 6 tune_task_name := dbms_sqltune.create_tuning_task 7 (sql_text => bad_sql_stmt, 8 user_name => ‘ZJY‘, 9 scope => ‘COMPREHENSIVE‘, 10 time_limit => 3600, 11 task_name => ‘zjy_sql_tuning_task‘, 12 description => ‘sql_tuning_advisor for this sql‘ 13 ); 14 end; 15 / PL/SQL procedure successfully completed.
3.可以修改调整任务的一些参数，比如：
SQL> begin 2 dbms_sqltune.set_tuning_task_parameter 3 (task_name => ‘zjy_sql_tuning_task‘, 4 parameter => ‘TIME_LIMIT‘, value => 1800 5 ); 6 end; 7 / PL/SQL procedure successfully completed.
4.开始执行调整任务：
SQL> begin 2 dbms_sqltune.execute_tuning_task 3 (task_name => ‘zjy_sql_tuning_task‘); 4 end; 5 / PL/SQL procedure successfully completed.
5.监控调整任务的执行状态：
SQL> select task_name, status, sofar, totalwork 2 from dba_advisor_tasks 3 join v$advisor_progress using(task_id) 4 where task_name = ‘zjy_sql_tuning_task‘; TASK_NAME STATUS SOFAR TOTALWORK ------------------------------ ----------- ---------- ---------- zjy_sql_tuning_task COMPLETED 1 1
6.查看调整任务最终给出的建议：
SQL> select dbms_sqltune.report_tuning_task(‘zjy_sql_tuning_task‘) from dual; DBMS_SQLTUNE.REPORT_TUNING_TASK(‘ZJY_SQL_TUNING_TASK‘) ------------------------------------------------------------------------------- GENERAL INFORMATION SECTION ------------------------------------------------------------------------------- Tuning Task Name : zjy_sql_tuning_task Tuning Task Owner : ZJY Workload Type : Single SQL Statement Scope : COMPREHENSIVE Time Limit(seconds): 1800 Completion Status : COMPLETED Started at : 01/23/2015 14:58:40 Completed at : 01/23/2015 14:58:58 ------------------------------------------------------------------------------- Schema Name: ZJY SQL ID : dmw0nx6g0b6h7 SQL Text : select owner, object_id, object_name from t where object_id=200000 ------------------------------------------------------------------------------- FINDINGS SECTION (2 findings) ------------------------------------------------------------------------------- 1- Statistics Finding --------------------- 尚未分析表 "ZJY"."T"。 Recommendation -------------- - 考虑收集此表的优化程序统计信息。 execute dbms_stats.gather_table_stats(ownname => ‘ZJY‘, tabname => ‘T‘, estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE, method_opt => ‘FOR ALL COLUMNS SIZE AUTO‘); Rationale --------- 为了选择好的执行计划, 优化程序需要此表的最新统计信息。 2- Index Finding (see explain plans section below) -------------------------------------------------- 通过创建一个或多个索引可以改进此语句的执行计划。 Recommendation (estimated benefit: 99.86%) ------------------------------------------ - 考虑运行可以改进物理方案设计的访问指导或者创建推荐的索引。 create index ZJY.IDX$$_3EC90001 on ZJY.T("OBJECT_ID","OWNER","OBJECT_NAME") ; Rationale --------- 创建推荐的索引可以显著地改进此语句的执行计划。但是, 使用典型的 SQL 工作量运行 "访问指导" 可能比单个语句更可取。通过这种方法可以获得全面的索引建议案, 包括计算索引维护的开销和附加的空间消耗。 ------------------------------------------------------------------------------- EXPLAIN PLANS SECTION ------------------------------------------------------------------------------- 1- Original ----------- Plan hash value: 1601196873 -------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 124 | 11904 | 3059 (1)| 00:00:37 | |* 1 | TABLE ACCESS FULL| T | 124 | 11904 | 3059 (1)| 00:00:37 | -------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter("OBJECT_ID"=200000) 2- Using New Indices -------------------- Plan hash value: 3141638344 ----------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ----------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | 96 | 4 (0)| 00:00:01 | |* 1 | INDEX RANGE SCAN| IDX$$_3EC90001 | 1 | 96 | 4 (0)| 00:00:01 | ----------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - access("OBJECT_ID"=200000) -------------------------------------------------------------------------------
7.删除调整任务：
SQL> exec dbms_sqltune.drop_tuning_task(‘zjy_sql_tuning_task‘) ; PL/SQL procedure successfully completed.
SQL Tuning 基础概述08 - SQL Tuning Advisor
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原文地址：http://www.cnblogs.com/jyzhao/p/3930567.html
