1：查看、修改AWR报告快照数据的采样间隔、保存策略
SQL> COL DBID FOR 999999999999
SQL> COL SNAP_INTERVAL FOR A26
SQL> COL RETENTION FOR A26
SQL> COL TOPNSQL FOR A10
SQL> select * from dba_hist_wr_control;
DBID SNAP_INTERVAL RETENTION TOPNSQL
------------- -------------------------- -------------------------- ----------
3990839260 +00000 01:00:00.0 +00014 00:00:00.0 DEFAULT
SQL>
SNAP_INTERVAL=+00000 01:00:00.0 表示采样间隔是1小时
RETENTION=+00014 00:00:00.0 表示采样数据保留期限是14天
如上所示，快照采样间隔为1小时一次，快照数据保留14天。修改AWR的快照采样间隔、保存配置，改为30分钟采集一次快照数据，快照数据库保留7天。如下所示：
SQL> COL DBID FOR 999999999999
SQL> COL SNAP_INTERVAL FOR A26
SQL> COL RETENTION FOR A26
SQL> select * from dba_hist_wr_control;
DBID SNAP_INTERVAL RETENTION TOPNSQL
------------- -------------------------- -------------------------- ----------
3990839260 +00000 01:00:00.0 +00014 00:00:00.0 DEFAULT
SQL> exec dbms_workload_repository.modify_snapshot_settings(interval=>30,retention=>7*24*60);
PL/SQL procedure successfully completed.
SQL> select * from dba_hist_wr_control;
DBID SNAP_INTERVAL RETENTION TOPNSQL
------------- -------------------------- -------------------------- ----------
3990839260 +00000 00:30:00.0 +00007 00:00:00.0 DEFAULT
SQL>
2：手动创建快照（Snapshots）
数据库创建快照（Snapshots）一般是按Schedule定期创建的，默认一般一小时创建一个快照，只有当数据库出现问题的时候，你才需要手工创建一个快照。以获取那个时间段内的相关数据。
SQL> exec dbms_workload_repository.create_snapshot();
PL/SQL procedure successfully completed.
手工创建快照后，可以通过dba_hist_snapshot视图查看创建的快照信息。
3：手动删除快照（Snapshots）
--不指定DBID，默认当前实例DBID
SQL> exec dbms_workload_repository.drop_snapshot_range(61263,61274);
PL/SQL procedure successfully completed.
--指定DBID
SQL> exec dbms_workload_repository.drop_snapshot_range(7417,7429,3990839260);
PL/SQL procedure successfully completed.
4：创建基线（baseline）
一般来说当AWR自动维护快照时，如果定义过baseline，与baseline相关的快照不会被删除，即使是过期的快照，这样就相当于手动保留了一份统计数据的历史信息，DBA可以在适当的时间将其与现有的快照进行对比，以生成相关的统计报表
SQL> COL BASELINE_NAME FOR A32;
SQL> SELECT DBID,BASELINE_NAME, START_SNAP_ID, END_SNAP_ID FROM DBA_HIST_BASELINE;
no rows selected
SQL> exec dbms_workload_repository.create_baseline(59806,59809,'20160726_07_11');
PL/SQL procedure successfully completed.
SQL> SELECT DBID,BASELINE_NAME, START_SNAP_ID, END_SNAP_ID FROM DBA_HIST_BASELINE;
DBID BASELINE_NAME START_SNAP_ID END_SNAP_ID
---------- -------------------------------- ------------- -----------
3990839260 20160726_07_11 59806 59809
SQL>
修改基线名称
BEGIN
DBMS_WORKLOAD_REPOSITORY.rename_baseline(
old_baseline_name => 'old_name',
new_baseline_name => 'new_name');
END;
/
基线（baseline）是自Oracle 10g开始引入的，不过只包括了一些简单的基线功能，创建一个基线允许保留指定范围内的快照用于性能对比，与AWR保留策略无关，可以使用DBMS_WORKLOAD_REPOSITORY包来管理这个功能，在11g中，它被增强了。新增了许多功能。例如固定基线、移动窗口（Moving Window）基线等
5: 删除基线（baseline）
首先查看基线设置,找到对应的baseline_name，然后删除，过程如下所示：
SQL>SELECT * FROM DBA_HIST_BASELINE;
SQL> COL BASELINE_NAME FOR A32;
SQL> SELECT DBID,BASELINE_NAME, START_SNAP_ID, END_SNAP_ID FROM DBA_HIST_BASELINE;
DBID BASELINE_NAME START_SNAP_ID END_SNAP_ID
---------- -------------------------------- ------------- -----------
2179993557 20110112 12980 13004
2179993557 20100616 7959 7968
2179993557 20100818 9461 9485
2179993557 20101020 10964 10988
2179993557 20110119 13148 13172
2179993557 20101222 12476 12500
2179993557 20100602 7624 7632
SQL> exec dbms_workload_repository.drop_baseline('20110112',true);
PL/SQL procedure successfully completed.
删除是如果指定了CASCADE参数为true，对应的snap也会被删除。
6: 查看快照记录信息
SELECT * FROM DBA_HIST_SNAPSHOT ORDER BY 1 DESC ;
SELECT SNAP_ID, DBID, INSTANCE_NUMBER, STARTUP_TIME,
BEGIN_INTERVAL_TIME, END_INTERVAL_TIME,
FLUSH_ELAPSED, SNAP_LEVEL, ERROR_COUNT
FROM WRM$_SNAPSHOT
WHERE STATUS = 0;
SELECT * FROM SYS.WRH$_ACTIVE_SESSION_HISTORY
7：导出、导入AWR快照数据
SQL> @?/rdbms/admin/awrextr.sql
SQL> @?/rdbms/admin/awrload.sql
8：删除导入的AWR快照数据。
如果要删除导入的awr数据，可以使用下面脚本进行删除。
exec dbms_swrf_internal.unregister_database(dbid);
sql> exec dbms_swrf_internal.unregister_database(3990839260);
dbms_workload_repository：
可以删除本地和其他数据库的快照，可以选择不同的快照来进行删除。
dbms_swrf_internal：
只能对其他数据库的快照来进行操作，会把整个快照unregister掉。
9：生成各种类型的AWR报告
Generating Various Types of AWR Reports
AWR reports can be generated by running various SQL scripts to satisfy various requirements. Each report is available in HTML or TXT format:
· awrrpt.sql
Displays various statistics for a range of snapshots Ids.
· awrrpti.sql
Displays statistics for a range of snapshot Ids on a specified database and instance.
· awrsqrpt.sql
Display statistics of a particular SQL statement for a range of snapshot Ids. Run
this report to inspect or debug the performance of a particular SQL statement.
· awrsqrpi.sql
Displays statistics of a particular SQL statement for a range of snapshot Ids on a specified SQL.
· awrddrpt.sql
Compares detailed performance attributes and configuration settings between two selected time periods.
· awrddrpi.sql
Compares detailed performance attributes and configuration settings between two selected time periods on a specific database and instance.
查看AWR报告里面某个具体SQL语句的执行计划
SQL> @?/rdbms/admin/awrsqrpt.sql
SQL> @?/rdbms/admin/awrsqrpi.sql
Workload Repository Views
The following workload repository views are available:
· V$ACTIVE_SESSION_HISTORY - Displays the active session history (ASH) sampled every second.
· V$METRIC - Displays metric information.
· V$METRICNAME - Displays the metrics associated with each metric group.
· V$METRIC_HISTORY - Displays historical metrics.
· V$METRICGROUP - Displays all metrics groups.
· DBA_HIST_ACTIVE_SESS_HISTORY - Displays the history contents of the active session history.
· DBA_HIST_BASELINE - Displays baseline information.
· DBA_HIST_DATABASE_INSTANCE - Displays database environment information.
· DBA_HIST_SNAPSHOT - Displays snapshot information.
· DBA_HIST_SQL_PLAN - Displays SQL execution plans.
· DBA_HIST_WR_CONTROL - Displays AWR settings.
参考资料：
