What is Oracle ASH report?

What is Oracle ASH report?

Overview of Active Session History To capture a detailed history of database activity, Oracle Database samples active sessions each second with the Active Session History (ASH) sampler. ASH is an integral part of the Oracle Database self-management framework and is extremely useful for diagnosing performance problems.

How can I get ash report?

Generating an ASH Report on the Local Database Instance

1. At the SQL prompt, enter: @$ORACLE_HOME/rdbms/admin/ashrpt.sql.
2. Specify whether you want an HTML or a text report: Enter value for report_type: text.
3. Specify the begin time in minutes before the system date: Enter value for begin_time: -10.

What is the use of ADDM report in Oracle?

Overview of the Automatic Database Diagnostic Monitor The Automatic Database Diagnostic Monitor (ADDM) is a self-diagnostic engine built into Oracle Database. ADDM examines and analyzes data captured in the Automatic Workload Repository (AWR) to determine possible performance problems in Oracle Database.

What is CPU wait in Oracle?

“CPU Wait” time is Oracle foreground process OS CPU run queue time. I ran an experiment (detailed below) and as the OS CPU utilization increased, so did the DB Time “gap” implying that the gap is CPU run queue time or at least a significant part of it.

What is active session Oracle?

An Active Session is defined as an Oracle session currently spending time in a database call, and the average activity of a session is the ratio of active to total wall clock time. Average Active Sessions. At a macroscopic level, DB Time is the sum of DB time over all sessions.

What is Active Session History in Oracle?

Oracle 10g introduced the Active Session History (ASH) as part of the Diagnostics and Tuning Pack. It samples information from the [G]V$ views allowing you to see current and historical information about active sessions on the database.

What is AWR in Oracle?

Automatic Workload Repository report or AWR report collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. Over the years Oracle has provided performance gathering tools and reporting tools. Earlier UTLBSTAT/UTLESTAT scripts were used for monitoring performance.

What is CPU wait?

CPU wait is a somewhat broad and nuanced term for the amount of time that a task has to wait to access CPU resources. This term is popularly used in virtualized environments, where multiple virtual machines compete for processor resources.

Where do I find the ASH report in Oracle?

The ASH reports are available from the “ASH Reports Viewer” node. The ASH Viewer tool gives a graphical view of active session history data within the Oracle instance. Interestingly, it is supports Oracle 8i onward.

How to generate active session history ( ASH ) report?

Active Session History (ASH) is a very important feature to analyze sessions in Oracle to troubleshoot transient problems that last for just few minutes. ASH reports gives the details needed to analyze the sessions. Below example shows how to generate ASH (Active Session History) reports from SQLPLUS.

When to use an ASH report in AWR?

The ASH report allows us to use samples and drill down to by time vs. snapshots, which comes in handy when we are inspecting particular set of transactions. We aren’t concerned with number of executions, which is offered in AWR, but not in samples with ASH. Running an ASH report after clicking on the button is quite easy.

How long does it take to get an ASH report?

As you can see, the samples are all about one minute each of an approximate five minute examination of the ASH sample time. We can see at the 3pm time, (just as was displayed in the Top Activity) the impact of the buffer exterminate wait, then the wait for CPU and cluster GC waits post the “hit”.