ORACLE AWR概述及生成AWR报告

浏览数：110 / 时间：2015年06月12日

1.Overview of the Automatic Workload Repository

The Automatic Workload Repository (AWR) collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. This data is both in memory and stored in the database. The gathered data can be displayed in both reports and views.

The statistics collected and processed by AWR include:

Object statistics that determine both access and usage statistics of database segments
Time model statistics based on time usage for activities, displayed in the V$SYS_TIME_MODEL and V$SESS_TIME_MODEL views
Some of the system and session statistics collected in the V$SYSSTAT and V$SESSTAT views
SQL statements that are producing the highest load on the system, based on criteria such as elapsed time and CPU time
ASH statistics, representing the history of recent sessions activity

Gathering database statistics using the AWR is enabled by default and is controlled by the STATISTICS_LEVEL initialization parameter. TheSTATISTICS_LEVEL parameter should be set to the TYPICAL or ALL to enable statistics gathering by the AWR. The default setting is TYPICAL. Setting STATISTICS_LEVEL to BASIC disables many Oracle Database features, including the AWR, and is not recommended. If STATISTICS_LEVELis set to BASIC, you can still manually capture AWR statistics using the DBMS_WORKLOAD_REPOSITORY package. However, because in-memory collection of many system statistics—such as segments statistics and memory advisor information—will be disabled, the statistics captured in these snapshots may not be complete. For information about the STATISTICS_LEVEL initialization parameter, see Oracle Database Reference.

2. Setting the Level of Statistics Collection

Oracle Database provides the initialization parameter STATISTICS_LEVEL, which controls all major statistics collections or advisories in the database. This parameter sets the statistics collection level for the database.

Depending on the setting of STATISTICS_LEVEL, certain advisories or statistics are collected, as follows:

BASIC: No advisories or statistics are collected. Monitoring and many automatic features are disabled. Oracle does not recommend this setting because it disables important Oracle Database features.
TYPICAL: This is the default value and ensures collection for all major statistics while providing best overall database performance. This setting should be adequate for most environments.（在生成ARW报告前，先检查参数STATISTICS_LEVEL，默认为TYPICAL即可）
ALL: All of the advisories or statistics that are collected with the TYPICAL setting are included, plus timed operating system statistics and row source execution statistics.
The V$STATISTICS_LEVEL view displays information about the status of the statistics or advisories controlled by the STATISTICS_LEVEL parameter. See "V$STATISTICS_LEVEL".可通过该视图查看这三个参数的信息。

SQL> desc v$statistics_level;
Name                         Type           Nullable Default Comments 
--------------------        -------------- -------- ------- -------- 
STATISTICS_NAME      VARCHAR2(64)     Y                         
DESCRIPTION             VARCHAR2(4000)  Y                         
SESSION_STATUS       VARCHAR2(8)        Y                         
SYSTEM_STATUS          VARCHAR2(8)        Y                         
ACTIVATION_LEVEL     VARCHAR2(7)         Y                         
STATISTICS_VIEW_NAME VARCHAR2(64)  Y                         
SESSION_SETTABLE     VARCHAR2(3)        Y

3.Generating Automatic Workload Repository Reports

An AWR report shows data captured between two snapshots (or two points in time). The AWR reports are divided into multiple sections. The HTML report includes links that can be used to navigate quickly between sections. The content of the report contains the workload profile of the system for the selected range of snapshots.

The primary interface for generating AWR reports is Oracle Enterprise Manager. Whenever possible, you should generate AWR reports using Oracle Enterprise Manager, as described in Oracle Database 2 Day + Performance Tuning Guide（在OEM界面生成AWR）.If Oracle Enterprise Manager is unavailable, you can generate AWR reports by running SQL scripts , as described in the following sections:

3.1 Generating an AWR Report(使用SQL脚本生成AWR)

The awrrpt.sql SQL script generates an HTML or text report that displays statistics for a range of snapshot IDs.

To generate an AWR report:

At the SQL prompt, enter:
```
@$ORACLE_HOME/rdbms/admin/awrrpt.sql
```
Specify whether you want an HTML or a text report:
```
Enter value for report_type: text
```
In this example, a text report is chosen.
Specify the number of days for which you want to list snapshot IDs.
```
Enter value for num_days: 2
```
A list of existing snapshots for the specified time range is displayed. In this example, snapshots captured in the last 2 days are displayed.
Specify a beginning and ending snapshot ID for the workload repository report:
```
Enter value for begin_snap: 150
Enter value for end_snap: 160
```
In this example, the snapshot with a snapshot ID of 150 is selected as the beginning snapshot, and the snapshot with a snapshot ID of 160 is selected as the ending snapshot.
Enter a report name, or accept the default report name:
```
Enter value for report_name: 
Using the report name awrrpt_1_150_160
```
In this example, the default name is accepted and an AWR report named awrrpt_1_150_160 is generated.