Oracle 11g AWR Series 7: Active session history (Ash) report

Generate Active session history (Ash) report

Role of ash report:
The ash report can be used to analyze Transient Performance issues that usually last for several minutes.
Performance Analysis of a specific range or target based on a variety of dimensions (such as time, session, module, action, or SQL _id) or a combination of these dimensions

Transient Performance problems are sustained for a very short period and will not occur in the analysis of the automatic database diagnostics Monitor (ADDM. ADDM taste
Report Major performance issues based on the impact of the database time during the analysis. If a specific problem persists for a short period of time
The severity may be even, or reduced due to other performance problems arising during analysis. Therefore, the problem record may not be found in ADDM.
Whether ADDM captures a performance issue depends on the duration of the issue and the interval between AWR snapshots.

If the duration of the performance issue is significantly higher than the snapshot interval, ADDM will capture the issue. For example, if the interval between snapshots is set to one hour
If the question lasts for 30 minutes, the question will not be considered an instant performance problem, because the duration is much longer than the snapshot interval and may be captured by ADDM.
To.

If a performance problem lasts for only 2 minutes, the problem may be a short performance problem, because the interval between the duration and the snapshot is very small,
It will not appear in problems found by ADDM. For example, if the user notifies you that the system is very slow between PM and PM
The time period between PM and PM, and no performance problems are displayed, a short performance problem may occur.
The time period lasts for only several minutes.

The following describes how to generate an ash report:

1. Generate a single instance ash report

@ $ ORACLE_HOME/rdbms/admin/ashrpt. SQL

2. generate an ash report for a specific database instance in the Oracle RAC Environment

@ $ ORACLE_HOME/rdbms/admin/ashrpti. SQL

3. Generate Oracle RAC ash report

@ $ ORACLE_HOME/rdbms/admin/ashrpti. SQL

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