exec dbms_workload_repository.create_snapshot();--调用MMON进程立即收集快照
生成AWR报告
@?/rdbms/admin/awrrpt.sql;
9.4.2 SQL语句级AWR报告分析
上面提到还有一个awrsqrpt.sql，它不是为整个实例生成报告，而是为某个特定SQL生成报告，这在优化某些特定SQL时可以隔离掉其他干扰因素，更易量化。如下：
SQL> @awrsqrpt.sql
Current Instance
~~~~~~~~~~~~~~~~
DB Id DB Name Inst Num Instance
----------- ------------ -------- ------------
83642957 ORA11G 1 ora11g
…此处快照开始和结束ID选择省去…
Specify the SQL Id
~~~~~~~~~~~~~~~~~~
Enter value for SQL_id: 8rmfvr1sw2wgn #SQL_ID需要先从V$SQL.sql_ID获取
SQL ID specified: 8rmfvr1sw2wgn
Specify the Report Name
~~~~~~~~~~~~~~~~~~~~~~~
The default report file name is awrsqlrpt_1_2327_2354.html. To use this name,
press <return> to continue, otherwise enter an alternative.
Enter value for report_name:
Using the report name awrsqlrpt_1_2327_2354.html
执行完成后，当前目录下会生成awrsqlrpt_1_2327_2354.html这个文件。
9.4.5 ASH分析
和AWR一样，ASH也是实时收集，并定期保存到V$动态性能视图中，用户可以通过查询动态视图或者ASH报告进行分析。Oracle会每秒对所有活跃会话（是指正在使用CPU或者等待非空闲事件的会话）进行一次采样，记录其当前等待的事件，该信息被存储SGA的ASH Buffer中，默认大小为32M，对应性能试图是V$ACTIVE_SESSION_HISTORY，并定期刷新到磁盘中，对应性能试图是DBA_HIST_ACTIVE_SESS_HISTORY。ASH中收集的信息包括会话当前正在执行的SQL以及执行计划，访问的对象信息比如对象号、文件号、块号，等待事件及其参数及其他信息。类似于AWR报告，一般通过ashrpt.sql或ashrpti.sql生成ASH报告，ashrpt生成的是整个实例的活动会话报告，ashrpti则是交互式的允许用户指定各种例如比如特定会话、特定SQL、特定模块等，和AWR不同，实例范围的ASH报告用的并不是很多，所以我们以ashrpti.sql生成特定会话的ASH为例。其生成如下：
[oracle@hs-test-10-20-30-14 ~]$ cd /u01/app/Oracle/product/11.2.0/dbhome_1/rdbms/admin/
[oracle@hs-test-10-20-30-14 admin]$ sqlplus "/as sysdba"
SQL> @ashrpti
…此处省区非必要信息…
ASH Samples in this Workload Repository schema
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Oldest ASH sample available: 24-Oct-18 09:00:06 [ 14629 mins in the past]
Latest ASH sample available: 03-Nov-18 12:48:12 [ 1 mins in the past]
Specify the timeframe to generate the ASH report
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Enter begin time for report:
-- Valid input formats:
-- To specify absolute begin time:
-- [MM/DD[/YY]] HH24:MI[:SS]
-- Examples: 02/23/03 14:30:15
-- 02/23 14:30:15
-- 14:30:15
-- 14:30
-- To specify relative begin time: (start with '-' sign)
-- -[HH24:]MI
-- Examples: -1:15 (SYSDATE - 1 Hr 15 Mins)
-- -25 (SYSDATE - 25 Mins)
Defaults to -15 mins
Enter value for begin_time:
Report begin time specified:
Enter duration in minutes starting from begin time:
Defaults to SYSDATE - begin_time
Press Enter to analyze till current time
Enter value for duration:
Report duration specified:
Using 03-Nov-18 12:33:55 as report begin time
Using 03-Nov-18 12:48:58 as report end time
Specify Slot Width (using ashrpti.sql) for 'Activity Over Time' section
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- Explanation:
-- In the 'Activity Over Time' section of the ASH report,
-- the analysis period is divided into smaller slots
-- and top wait events are reported in each of those slots.
-- Default:
-- The analysis period will be automatically split upto 10 slots
-- complying to a minimum slot width of
-- 1 minute, if the source is V$ACTIVE_SESSION_HISTORY or
-- 5 minutes, if the source is DBA_HIST_ACTIVE_SESS_HISTORY.
Specify Slot Width in seconds to use in the 'Activity Over Time' section:
Defaults to a value as explained above:
Enter value for slot_ 10
Slot Width specified: 10
Specify Report Targets (using ashrpti.sql) to generate the ASH report
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- Explanation:
-- ASH Report can accept "Report Targets",
-- like a particular SQL statement, or a particular SESSION,
-- to generate the report on. If one or more report targets are
-- specified, then the data used to generate the report will only be
-- the ASH samples that pertain to ALL the specified report targets.
-- Default:
-- If none of the report targets are specified,
-- then the target defaults to all activity in the database instance.
Specify SESSION_ID (eg: from V$SESSION.SID) report target:
Defaults to NULL:
Enter value for target_session_id: 1144
SESSION report target specified: 1144
Summary of All User Input
-------------------------
Format : HTML
DB Id : 83642957
Inst num : 1
Begin time : 03-Nov-18 12:33:55
End time : 03-Nov-18 12:48:58
Slot width : 10 seconds
Report targets : 1
Report name : ashrpt_1_1103_1248.html