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This confirms whether the derived rates are really of interest: A third type of statistical data collected by Oracle is sampled data. This chapter discusses the gathering of performance statistics.

01 | Sql | Oracle Database

With these default settings, a typical system with an average of 10 concurrent active sessions can require approximately to MB of space for its AWR performanec. To look at the system as a whole, it is perdormance to have a common scale for comparisons. If the hardware shows response times much higher than the normal performance value, then it is performing badly or is overworked. This data is both in memory and stored in the database.

If NULL is specified, the existing value is preserved. It is possible to change the default values for both snapshot interval and retention period. However if your system is subjected to a monthly peak load during month end book closing, you may have to oracle 10g performance tuning pdf download the retention period to one month.

System performance degrades rapidly and unpredictably when paging or swapping occurs. 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 since the instance started up.

It is calculated oracle 10g performance tuning pdf download aggregating the CPU ogacle wait times of all sessions not waiting on idle wait events non-idle user sessions. These statistics show if the disk is performing optimally or if the oracle 10g performance tuning pdf download is being overworked.

See “Automatic Database Diagnostic Monitor”. These additional statistics allow better analysis of what is actually being executed on the Dowload. First, specify whether you want an HTML or a text report. Virtual memory statistics should mainly be used as a check to validate that there is very little paging or swapping activity on downlkad system.

This problem is particularly acute on shared server applications on middle tier machines where session state may persist across user interactions, and on completion state information that is not fully deallocated.

It is always best to consider operating system statistics as a diagnostic tool, similar to the way many doctors use body temperature, pulse rate, and patient pain when making a diagnosis.

5 Automatic Performance Statistics

However, you can view the statistics with the following views:. For example, the number database calls per second is a metric. This statistics represents the total time spent in database calls and is a indicator of the total instance workload. Typically, these events are of no value when investigating performance problems, and they should be ignored when examining the wait events. See “Automatic Workload Repository”.

For example, a instance that has been running for 30 minutes could have four active user sessions whose cumulative DB time is approximately minutes. These ratios should not oracle 10g performance tuning pdf download used as ‘hard and fast’ identifiers of whether there is or is not a performance bottleneck.

The most important disk statistics are the current response time and the length of the disk queues.

AWR supports the capture of baseline oracle 10g performance tuning pdf download by enabling you to specify and preserve a pair or range of AWR snapshots as dowmload baseline. This sampling is performed by the active session history ASH sampler. This data is useful for comparing the total wait time for an event to the total elapsed time between the performance data collections.

Such ratios include the buffer cache hit ratio, oracle 10g performance tuning pdf download soft-parse ratio, and the latch hit oracle 10g performance tuning pdf download. Even an event that had a wait of 30 minutes in a 45 minute snapshot might not be indicative of a problem if you discover that there were users on the system, and the host hardware was orzcle 64 node machine.

The optional database identifier is Using the common time instrumentation helps to identify quantitative effects on the database operations. A smaller snapshot interval increases the frequency, which increases the oracle 10g performance tuning pdf download of data collected by the Automatic Workload Repository. The pair of snapshots associated with the baseline are retained until you explicitly drop the baseline.

Most operating systems report CPU usage as time spent in user space or mode and time dpf in kernel space or mode. Database statistics provide information on the type of load on the database, as well as oracpe internal and external resources used by the database. If you want to specify a database and instance before entering a range of snapshot Ids, run the awrrpti.

By capturing only active sessions, a manageable set of data downlaod represented with the size being directly related to the work being performed rather than the number of sessions allowed on the system.

The Automatic Workload Repository AWR collects, processes, and maintains performance statistics for problem detection and self-tuning purposes. The reports are divided into multiple sections. To generate a text report for a range of snapshot Ids, run the awrrpt. A powerful tool for diagnosing performance problems is the use of statistical baselines.


DB time is measured 10t from the time that the instance was started. Oracle Enterprise Manager Concepts and Oracle Enterprise Manager online help for information about monitoring and diagnostic tools available with Oracle Enterprise Manager.

Utilization for each CPU can detect single-threading and scalability issues. The Automatic Workload Repository space consumption can be reduced by the increasing the snapshot interval and reducing the retention period.

The system automatically assign a unique baseline Id to the new baseline preformance the baseline is created. After that, a list of the database Ids and instance numbers displays, similar to the following:.

The HTML report includes links that can be used oracle 10g performance tuning pdf download navigate quickly between sections. This result simply means that there is no meaningful value for the statistic. Next, accept the default report name or enter a report name.