oracle 基线与优化（三）

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本文介绍了一种使用Oracle SQL性能分析工具进行SQL调优的方法，包括如何创建SQL集、捕获SQL执行情况、导出及导入SQL集，以及通过不同类型的执行任务来评估SQL语句在不同环境下的性能表现。

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oracle 基线与优化:

生产库sts获取：

BEGIN
  dbms_sqltune.create_sqlset(sqlset_name => 'SPS5', sqlset_owner => 'SYS');
END;
begin
  DBMS_SCHEDULER.CREATE_JOB(job_name   => 'SPS5',
                            job_type   => 'PLSQL_BLOCK',
                            job_action => 'DECLARE bf VARCHAR2(98); 
                                           BEGIN
                                              <span style="color:#ff6666;"> bf := q''#UPPER(PARSING_SCHEMA_NAME) = ''SYS'' AND UPPER(SQL_TEXT) = ''SELECT COUNT(*) FROM SYS.SPS_TEST'' #'</span>'; 
                                               dbms_sqltune.capture_cursor_cache_sqlset( sqlset_name=>''SPS5'', 
                                                                                         time_limit=>''120'', 
                                                                                         repeat_interval=>''5'', 
                                                                                         basic_filter=>bf, 
                                                                                         sqlset_owner=>''SYS'');
                                           END;',
                            enabled    => TRUE);
end;

生产库sts信息查询：

select name,statement_count from dba_sqlset;

导出前准备：（帮助理解）

BEGIN
  DBMS_SQLTUNE.CREATE_STGTAB_SQLSET('PACK_SQLSET', 'SYSTEM');
END;
BEGIN
  DBMS_SQLTUNE.PACK_STGTAB_SQLSET('SP52', 'SYS', 'PACK_SQLSET', 'SYSTEM');
END;
SELECT * FROM SYSTEM.PACK_SQLSET

导出并传输到测试库：

执行：

begin
   DBMS_SQLTUNE.UNPACK_STGTAB_SQLSET('SPS5','SYS',TRUE,'PACK_SQLSET','SYSTEM');
end;

测试库上执行语句：

alter system flush buffer_cache;
alter system flush shared_pool;
select count(*) from SYS.SPS_TEST;
SELECT COUNT(*) FROM SYS.SPS_TEST

创建执行SQL分析

declare
  sts_task varchar2(64);
begin
  sts_task := dbms_sqlpa.create_analysis_task(task_name   => 'SPS5',
                                              description => 'experiment11gR2 execute',
                                              sqlset_name => 'SPS5');
end;

执行分析：

declare
  exe_task varchar2(64);
begin
  exe_task := dbms_sqlpa.execute_analysis_task(task_name      => 'SPS5',
                                               execution_name => 'SPS51',
                                               execution_type => 'CONVERT SQLSET', <span style="color:#3333ff;"> --sts获取</span>
                                               execution_desc => '11g sql trail');
end;

declare
  exe_task varchar2(64);
begin
  exe_task := dbms_sqlpa.execute_analysis_task(task_name      => 'SPS5',
                                               execution_name => 'SPS52',
                                               execution_type => 'TEST EXECUTE',
                                               execution_desc => '11g sql trail2');
end;

比较

begin
  DBMS_SQLPA.EXECUTE_ANALYSIS_TASK(task_name        => 'SPS5',
                                   execution_type   => 'COMPARE PERFORMANCE',
                                   execution_name   => 'Compare_elapsed_time2',
                                   execution_params => dbms_advisor.arglist('execution_name1',
                                                                            'SPS51',
                                                                            'execution_name2',
                                                                            'SPS52',
                                                                            'comparison_metric',
                                                                            'elapsed_time'));
end;

查看结果：

select xmltype(dbms_sqlpa.report_analysis_task('SPS5', 'html', 'typical', 'all', null, 100, 'Compare_elapsed_time')).getclobval(0, 0)
from dual;

General Information

Task Information:

Workload Information:

Task Name	: SPS5
Task Owner	: SYS
Description	:

SQL Tuning Set Name	: SPS5
SQL Tuning Set Owner	: SYS
Total SQL Statement Count	: 2

Execution Information:

Execution Name	: Compare_elapsed_time
Execution Type	: COMPARE PERFORMANCE
Description	:
Scope	: COMPREHENSIVE
Status	: COMPLETED

Started	: 12/28/2014 17:30:05
Last Updated	: 12/28/2014 17:30:05
Global Time Limit	: UNLIMITED
Per-SQL Time Limit	: UNUSED
Number of Errors	: 0

Analysis Information:

Before Change Execution:

After Change Execution:

Execution Name	: SPS51
Execution Type	: CONVERT SQLSET
Scope	: COMPREHENSIVE
Status	: COMPLETED
Started	: 12/28/2014 17:24:52
Last Updated	: 12/28/2014 17:24:52
Global Time Limit	: UNLIMITED
Per-SQL Time Limit	: UNLIMITED

Execution Name	: SPS52
Execution Type	: TEST EXECUTE
Scope	: COMPREHENSIVE
Status	: COMPLETED
Started	: 12/28/2014 17:27:32
Last Updated	: 12/28/2014 17:27:33
Global Time Limit	: UNLIMITED
Per-SQL Time Limit	: 60
Number of Errors	: 0

Comparison Metric:ELAPSED_TIME

Workload Impact Threshold:1%

SQL Impact Threshold:1%

Report Summary

Projected Workload Change Impact:

Overall Impact	:	99.5%
Improvement Impact	:	99.5%
Regression Impact	:	0%

SQL Statement Count

SQL Category	SQL Count	Plan Change Count
Overall	2	0
Improved	2	0

Top 2 SQL Sorted by Absolute Value of Change Impact on the Workload

object_id	sql_id	Impact on Workload	Execution Frequency	Metric Before	Metric After	Impact on SQL	Plan Change
6	ff9p4xt2sqhd4	77.3%	63	10253.7301587302	56	99.45%	n
5	ah0402tq401hh	22.2%	17	10892.1764705882	38	99.65%	n

Report Details

SQL Details:

Object ID	: 6
Schema Name	: SYS
SQL ID	: ff9p4xt2sqhd4
Execution Frequency	: 63
SQL Text	: select count(*) from SYS.SPS_TEST

Execution Statistics:

Stat Name	Impact on Workload	Value Before	Value After	Impact on SQL
elapsed_time	77.3%	.010254	.000056	99.45%
parse_time			.000121
cpu_time	76.6%	.008914	0	100%
user_io_time			0
buffer_gets	78.63%	2050	3	99.85%
cost	3138.71%	558	2	99.64%
reads	0%	0	0	0%
writes	0%	0	0	0%
io_interconnect_bytes			0
rows		1	1

Notes:

After Change:

该语句已首先执行以预热缓冲区高速缓存。
显示的统计信息是后面的 9 执行的平均值。

Findings (1):

此 SQL 的性能得到了改善。

Execution Plan Before Change:

Plan Hash Value	: 3930752761

Id	Operation	Name	Rows	Cost	Time
0	SELECT STATEMENT			558
1	. SORT AGGREGATE		1
2	.. TABLE ACCESS FULL	SPS_TEST	143778	558	00:00:07

Execution Plan After Change:

Plan Id	: 202
Plan Hash Value	: 3930752761

Id	Operation	Name	Rows	Cost	Time
0	SELECT STATEMENT		1	2	00:00:01
1	. SORT AGGREGATE		1
2	.. TABLE ACCESS FULL	SPS_TEST	1	2	00:00:01