Automatic Performance Statistics


awr report

AWR Report • The AWR report is the most well known performance report. • Oracle tuning professionals frequently start their analysis with this report. • AWR report contains much data – but contains no concrete recommendations for action. The procedure of report generation in Oracle10g is quite different with AWR. The final AWR report can be built by using the PL/SQL API provided in the dbms_workload_repository package. Two procedures that generate AWR reports from are awr_report_text and awr_report_html. These procedures generate the AWR report for the specified. Dec 14,  · I have been looking out for help to understand AWR. i did find some resources but many were vague or incomplete or had issue of some sort. Can someone, please point to a resource where i can read and understand AWR on Oracle 12C database.

AWR report Oracle 12C | Oracle Community

This chapter discusses the gathering of performance statistics. This chapter contains the following topics:. To effectively diagnose performance problems, statistics awr report be available. Oracle Database generates many types of cumulative statistics for the system, awr report, sessions, and individual SQL statements.

Oracle Database also tracks cumulative statistics on segments and services. When analyzing a awr report problem in any of these scopes, you typically look at the change in statistics delta value over the awr report you are interested in.

Specifically, you look at the difference between the cumulative value of a statistic at the start of the period and the cumulative value at the end, awr report. Note that the cumulative values in dynamic views are reset when the database instance is shutdown. The Automatic Workload Repository AWR automatically awr report the cumulative and delta values for most of the statistics at all levels except the session level.

This process is repeated on a regular time period and the result is called an AWR snapshot. The delta values captured by the snapshot represent the changes for each statistic over the time period, awr report. See "Overview of the Automatic Workload Repository". A metric is another type of statistic collected by Oracle Database. A metric is defined as the rate of change in some cumulative statistic, awr report.

That rate can be measured against a variety of units, including time, transactions, or database calls. For example, the number database calls per second is a metric.

A third type of statistical data collected by Oracle is sampled data. The active session awr report ASH sampler performs the sampling, awr report. ASH samples the current state of all active sessions. AWR snapshot processing also writes it to persistent storage. See "Active Session History". A powerful tool for diagnosing performance problems awr report the use of statistical baselines.

A statistical baseline is collection of statistic rates usually taken over time period where the system is performing well at peak load, awr report. Comparing statistics captured during a period of bad performance to a baseline helps discover specific statistics that awr report increased significantly and could be the cause of the problem.

AWR supports the capture of baseline data by enabling you to specify and preserve a pair or range of AWR snapshots as a baseline. Carefully consider the time period you choose as a baseline; the baseline should be a good representation of the peak load on the system.

In the future, you can compare these baselines with snapshots captured during periods of poor performance. Oracle Enterprise Manager is the recommended tool for viewing both real time data in the dynamic performance views and awr report data from the AWR history tables. Enterprise Manager can also be used to capture operating system and network statistical data that can be correlated with AWR data, awr report.

Database statistics provide information on the type of load on the database and the internal and external resources used by the database. This section describes some of the more important statistics. Wait events awr report statistics that are incremented by a server process awr report thread to indicate that it had to wait for an event to complete before being awr report to continue processing.

To enable easier high-level analysis of the wait events, events are grouped into awr report. The wait classes awr report based on a common solution that usually applies to fixing a problem with the wait event.

For example, awr report, exclusive TX locks are generally an application level issue and HW locks are generally a configuration issue. Wait event statistics for an instance include statistics for both background and foreground processes. When tuning an Oracle database, awr report, each component has its own set of statistics. To look at the system as a whole, awr report, it is necessary to have a common scale for comparisons.

For this reason, most Oracle Database advisories and reports describe statistics in terms of time. Using the common time instrumentation helps to identify quantitative effects on the database operations. The most important of the time model statistics is DB time. This statistics represents the total time spent in database calls and is an indicator of the total instance workload, awr report.

It is calculated by aggregating the CPU and wait times of all sessions not waiting on idle wait events non-idle user sessions, awr report. DB time is measured cumulatively from the time of instance startup. Because DB time it is calculated by combining the times from all non-idle user sessions, it is possible that the DB time can exceed the actual time elapsed after the instance started.

For example, an instance that has been running for 30 minutes could have awr report active user sessions whose cumulative DB time is approximately minutes. The objective for tuning an Oracle system could be stated as reducing the time that users spend in performing some action on the database, or simply reducing DB time.

Other time model statistics provide quantitative effects in time on specific actions, such as logon operations and hard and soft parses. Active sessions are sampled every second and are stored in a circular buffer in SGA.

Any session that is connected to the database and is waiting for an event that does not belong to the Idle wait class is considered as an active session. This includes any session that was on the CPU at the time of sampling.

Because the active session samples are stored in a circular buffer in SGA, the greater the system activity, the smaller the number of seconds of session activity that can be stored in the circular buffer. Awr report capturing only active sessions, a manageable set of data is represented with the size being directly related to the work being performed rather than the number of sessions allowed awr report the system.

The data present in ASH can awr report rolled up on various dimensions that it captures, including the following:. You can gather ASH information over a specified duration into a report.

Operating system statistics provide information on the usage and performance of the main hardware components awr report the system, and the performance of the operating awr report itself. This information is crucial for detecting potential resource exhaustion, such as CPU cycles and physical memory, and for detecting bad performance of peripherals, such as disk drives.

Operating system statistics are an indication of how the hardware and operating system are working. Many system analysts react to a hardware resource shortage awr report installing more hardware.

This is a reactionary response to a series of symptoms shown in the operating system statistics. It is best to consider operating system statistics awr report a diagnostic tool, similar to the way doctors use body temperature, pulse rate, and patient pain when making a diagnosis, awr report.

To help identify bottlenecks, gather operating system statistics for all servers in the system under performance analysis, awr report. CPU utilization is the most important operating system statistic in the tuning process. Utilization for each CPU can detect single-threading and scalability issues.

Most operating systems report CPU usage as time spent in user space or mode and time spent in kernel space or mode. These additional statistics allow better analysis of what is actually being executed on the CPU. On a system running Awr report Database, where only one application is typically running, awr report, the system runs database activity in user space. Using both sets of statistics enable you to determine whether the Oracle database or other system activity is the cause of the CPU problems.

V irtual memory statistics should mainly be used as a check to validate that there is very little paging or swapping activity on the system. System performance degrades rapidly and unpredictably when paging or swapping occurs.

Individual process memory statistics can detect memory leaks due to a programming failure to deallocate memory taken from the process heap. These statistics are necessary to validate that memory usage does not increase after the system has reached a steady state after startup. This awr report is particularly acute on shared server applications on middle tier computers where session state may persist across user interactions, and on completion state information that is not fully deallocated.

Most operating systems provide extensive statistics on disk performance. The most important awr report statistics are the current response time and the length of the disk queues. These statistics show if the disk is performing optimally or if the disk is being overworked. If the hardware shows response times much higher than the normal performance value, awr report, then it is performing badly or is overworked.

This is your bottleneck. If disk queues start to exceed two, then the disk is a potential bottleneck of the system. These statistics are captured for both single and multi block read and write operations in the following dimensions:. The database samples cumulative statistics every hour and stores them as historical statistics in the AWR. You can use network statistics in much the same way as disk statistics to determine if a network or network interface is overloaded or not performing awr report. In today's networked applications, network latency can be a large portion of the actual awr report response time.

For this reason, these statistics are a crucial debugging tool. Table shows the various tools for gathering operating statistics on UNIX.

For Windows, use the Performance Monitor tool. When initially examining performance data, you can formulate potential theories by examining your statistics. One way to ensure that your interpretation of the statistics is correct is to perform cross-checks with other data. This establishes whether awr report statistic or event is really of interest. Also, awr report, because awr report activities are tunable, it is better to first analyze the statistics from foreground activities before analyzing the statistics from background activities.

When tuning, it is common to compute a ratio that helps determine whether there is a problem. Awr report ratios include the buffer cache hit ratio, awr report, the soft-parse ratio, and the latch hit ratio. Do not use these ratios as definitive identifiers of whether a performance bottleneck exists.

Rather, awr report, use them as indicators. To identify whether a bottleneck exists, examine other related evidence.

This data is useful for comparing the total wait time for an event to the total elapsed time between the data collections. For example, if the wait event accounts for only 30 seconds out of a 2-hour period, then little is to be gained by investigating this event, although it may be the highest ranked wait event when ordered by time waited.

However, awr report, if the event accounts for 30 minutes of a minute period, then the event is worth investigating, awr report. See "Wait Events".


How to generate AWR report from Oracle Database -


awr report


Dec 14,  · I have been looking out for help to understand AWR. i did find some resources but many were vague or incomplete or had issue of some sort. Can someone, please point to a resource where i can read and understand AWR on Oracle 12C database. The Oracle’s Automatic Workload Repository (AWR) collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. The report generated by AWR is a big report and it can take years of experience to actually understand all aspects of this report. Home / DATABASE, HOW TO / How to generate AWR report in oracle. How to generate AWR report in oracle. views Less than a minute 2. The Automatic Workload Repository (AWR) collects and maintains statistics of the database.