Can you please explain about the db time now shown in statspack reports 10g. The explanation I know of is: it is the time spent in database since instance startup. Can you please elaborate this. I can see that db time shown in statspack is more than the elapsed time. For eg, a statspack report of snaps taken between 15 minutes shows db time greater than 15 minutes. How is this possible?
Thanks always. Regards, Albert Nelson A. It is sort of like looking at wait events. How can you have 30 minutes of enqueue wait in 15 minutes? Easy - 30 people waited one minute apiece, or two people waited 15 minutes or You have more than one thing contributing "time" the database. Reviews April 23, - pm UTC. You can also catch regular content via Connor's blog and Chris's blog.
Or if video is more your thing, check out Connor's latest video and Chris's latest video from their Youtube channels. And of course, keep up to date with AskTOM via the official twitter account. Questions DB time. Question and Answer. Latest Followup. I have 8 CPU. Total of both is greater than total DB time.
Response-Time Analysis Made Easy in Oracle Database 10g
Actually What is "sql execute elapsed time"? I look at latch and there is nothing significant, most of latch has 0. Excellant Tom, You explain everything just in two lines. Thanks a lot. Hey Tom, One more qestion. I checked and found one of session Which is external procedure for Advance Queuing has increment in " user iccf games by every seconds by "user rollback". My confusion is why? Because it's run as external procedure?
Because that user is calling one of in built procedure, how to tune that? What kind of resource it use? UNDO segments, redo logs? Would you please explain this. Tom, Following query give me first 2 users with highest "User Rollback". VALUE value ,n. NAME name, ses. SID --and p.
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That I read e. EDIT: my guess now as the question have been posted that this metric is in seconds, although units are not mentioned in AWR and I could not find about it in web by awr db time in sec search.
Please provide link where it's confimed for sure if it is so. I actually get the reports via automated system, so cannot be sure they not mangled along the way Please add in comment if it can be done on stackoverflow. My guess is that due to lots of info to fit on one line of compare AWR developers of the report decided to skip s : which is present on the same place in ordinary not compare AWR.
Learn more. Asked 1 year, 1 month ago. Active 1 year, 1 month ago. Viewed 84 times. Then Load Profile says: 1st per sec DB time: 1. Alexei Martianov. Alexei Martianov Alexei Martianov 1, 2 2 gold badges 14 14 silver badges 37 37 bronze badges. What is the question? Now it is hard to answer. Marmite Bomber, edited, thank you for your suggestion.Register and Participate in Oracle's online communities.
Learn from thousand of experts, get answers to your questions and share knowledge with peers. Module: nqsserver ladtmyyq. As above the AWR report ,the DB time is too more rather than elapsed timing ,I think the elapsed time should be high in compare to db time ,so as per the above comment ,there is no scope in database level tuning. Thus, between and on Jun, 60minutes i.
Thanks for your reply i got it, Is there any need to change in db level for performance or i have to look on sql query for tuning please suggest. The actual question would be that do you really have an issue with the database that you are trying to resolve or it's just an attempt to make the db run "more faster"?
Take action only if there is really a problem to be solved. Aggregate data from AWR doesn't help you address such a problem. Thanks for your reply, main concern is that they have given me some query for tune which are mainly used in reports in pre-production environment if it works fine then it will be deploy on production. So for that reason i have generated AWR report 1st and analysed and asking the query.
If you have a specific query to tune, an AWR report doesn't help. And with what you have posted, it doesn't seem as if that query is also having any issue. See if you can get specific details about why the query needs tuning and if it is indeed problematicdo you have any history of it' previous execution available?
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Transactions per second
This discussion is archived. I have the same question Show 0 Likes 0. This content has been marked as final. Show 12 replies. Hemant K Chitale. Regards Arya. You have misunderstood the statistics. Regards, Arya. Do you have performance problem? Go to original post.In a nutshell, an Oracle database is a mechanism to store and retrieve large volumes of data, and many end-users visualize Oracle as a big electronic filing cabinet.
This filing cabinet must be fast and people have come to expect sub-second response time. These instant response time expectations are driven by tools like Google that can scan a billion web sites for keywords in a fraction of a second. But how do you make your Oracle system as fast as Google? Speed is all about delivering the goods, and serving-up the data. Also see rows per second Oracle throughput Tips. Let's explore the relative speeds of disk storage.
IEEE a, in its peer-to-peer bus topology, allows to Mbps data transfer rates for up to 63 nodes, allowing 16 hops at 4.
If used with Category 5 UTP wiring you can get Mbps over meter plastic optical fiber and Mbps over meters of glass optical fiber. Its performance is excellent.
For a multi-user sequential workload, it can sustain MBps of read throughput. PC Oracle disk speeds:. The company quotes the storage disk as reading data at 57 Mbytes per second MBps and writes at 32MBps. Also, this informative SSD Speed page has details on solid-state disk technology. Elapsed Sec : 2, There are many vendors who offer rack-mount solid-state disk that work with Oracle databases, and the competitive market ensures that product offerings will continuously improve while prices fall.
Here are the major SSD vendors for Oracle databases vendors are listed alphabetically :. Advanced Media Inc. Burleson Consulting does not partner with any SSD vendors and we provide independent advice in this constantly-changing market. BC experts can also help you choose the SSD that is best for your database. Flash SSD. The flash type SSD suffers from serious shortcomings, namely a degradation of access speed over time. At first, Flash SSD is 5 times faster than a platter disk, but after some usage the average read time becomes far slower than a hard drive.
Feel free to ask questions on our Oracle forum. Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.
Oracle technology is changing and we strive to update our BC Oracle support information. If you find an error or have a suggestion for improving our content, we would appreciate your feedback. All rights reserved by Burleson. Disk enqueues can occur when the disk is unable to quickly service concurrent requests. Super-large disks can be problematic, and the most popular Oracle data files can be placed on the middle absolute track of the device to minimize read-write head movement.
Market Survey of SSD vendors for Oracle: There are many vendors who offer rack-mount solid-state disk that work with Oracle databases, and the competitive market ensures that product offerings will continuously improve while prices fall. SearchStorage notes that SSD is will soon replace platter disks and that hundreds of SSD vendors may enter the market: "The number of vendors in this category could rise to several hundred in the next 3 years as enterprise users become more familiar with the benefits of this type of storage.
Read speed Avg. Search BC Oracle Sites. Fibre Channel InfiniBand. Violin Solid Access Technologies.There may be times when a query is taking longer to execute than expected. With Oracle, the Automatic Workload Repository collects statistics on a regular schedule to report on how the system is performing, including elapsed time for queries. Let's look at a script that does that and see how it can report longer elapsed times.
One item to notice is the target time is entered when the script is called, which eliminates any statements executing in less time than the supplied lower limit. The next sections return the elapsed times for current queries and statements as total elapsed time across all executions and as elapsed time by execution; this can be helpful in determining if a total elapsed time for a given statement indicates a problem.
Having such a script handy can save time and effort in troubleshooting long elapsed query times by revealing whether or not multiple executions of a statement occurred during the snapshot window and can provide a total elapsed time across snapshots so an accurate time can be obtained.
And such a report can be much easier to use than a full AWR or ASH report as it isolates the elapsed time data from the rest of the repository statistics. See all articles by David Fitzjarrell. Advertiser Disclosure: Some of the products that appear on this site are from companies from which QuinStreet receives compensation.
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Oracle Data Mining: Classification. July 5th, AM. Find duplicates - Unique IDs. July 2nd, AM. April 25th, PM. Update values of one table based on condition of values in other table using Trigger. February 29th, PM.With Oracle Database 10g, many previously difficult-to-attain response-time metrics are now at your fingertips. Historically, in trying to achieve maximum database performance, Oracle DBAs and performance analysts have fought an uphill battle to obtain solid response time metrics for system as well as user session activity.
The problem facing DBAs has always had two facets: first, determining exactly "where" the database or user sessions have been spending their time; and second, determining the objective nature of the user experience. Given all the possible activities and interactions within the database, these tasks are far from trivial. The Oracle Wait Interface, which was introduced many versions ago, has been a great jump-start for admins who know how to use it, but even it has lacked the ideal ability to tell a DBA how well the system or user sessions have efficiently processed transactions or queries.
Enabling and poring over trace files can garner this level of detail, but for most overworked DBAs who have to manage large database farms, this exercise is a luxury. Fortunately, those Oracle DBAs who have upgraded to Oracle Database 10 g will find major response-time enhancements that allow a much better picture to be presented about system and session-level response-time metrics.
Database Block Changes (per second)
In this article, I'll explore the use of some of these historical mechanisms at the system, session, and SQL levels. First of all, part of the answer to how well, in general, a database is running can be obtained by issuing this query in Oracle Database 10 g :. The Database CPU Time Ratio is calculated by dividing the amount of CPU expended in the database by the amount of "database time," which is defined as the time spent by the database on user-level calls with instance background process activity being excluded.
You can also take a quick look over the last hour to see if the database has experienced any dips in overall performance by using this query:. The query above contains more response-time metrics than simply the Database CPU and Wait Time Ratios we'll cover those laterbut you can see the benefit in being able to acquire this information.
The next question DBAs pose at the system level involves the average level of response time that their user community is experiencing. Prior to Oracle Database 10 g this type of data was difficult to capture, but not anymore.
For example, the statistics shown above report that the maximum response time per user transaction has been only.
Oracle certainly wouldn't be to blame in this case. If, however, response times are longer than desired, the DBA will then want to know what types of user activities are responsible for making the database work so hard. Again, before Oracle Database 10 gthis information was more difficult to acquire, but now the answer is only a query away:. In addition to active time, a DBA will want to know the global wait times as well. As with response-time metrics, you can also look back in time over the last hour with a query like this one:.
You can also view current session wait activity using the new wait classes using the following query:. You'll also find the new wait classes in these two modified views with Oracle Database 10 g. If you need to look back in time to discover what sessions were logged on and consuming the most resources, you can use the following query. In the example below, we're looking at activity from midnight to 5 a. This view gives you a lot of excellent information without the need for laborious tracing functions.
We'll see more use of it in the next section, which deals with analyzing the response times of SQL statements.The Performance page in Oracle Enterprise Manager Enterprise Manager displays information in three sections that you can use to assess the overall performance of the database in real time. In some cases, however, you may want to monitor the database performance in real time to identify performance problems as they happen.
However, if you notice a sudden spike in database activity on the Performance page, then you may want to investigate the incident before the next ADDM analysis. By drilling down to appropriate pages from the Performance page, you can identify performance problems with the database in real time.
If you find a performance problem, then you can choose to run ADDM manually to analyze it immediately, without having to wait until the next ADDM analysis. The Average Active Sessions chart of the Performance page shows potential problems inside the database, including how much CPU users are consuming. By following the performance method explained in Chapter 2, "Oracle Database Performance Method"you can drill down from the charts to identify the cause of instance-related performance issues and resolve them.
All other values in the chart represent users waiting and contention for resources, which are categorized by wait classes in the legend. Values that use a larger block of active sessions represent bottlenecks caused by a particular wait class, as indicated by the corresponding color in the legend.
In the chart shown in Figurethe largest block of activity appears in green and corresponds to the CPU Used wait class as described in the legend. To identify each wait class, move your cursor over the block in the Average Active Sessions chart corresponding to the class.
Click the largest block of color on the chart or its corresponding wait class in the legend to drill down to the wait class with the most active sessions. The Active Sessions Working page shows a 1-hour time line. Details for each wait class are shown in 5-minute intervals under Detail for Selected 5 Minute Interval. You can view the details of wait classes in different dimensions by proceeding to one of the following sections:. The information contained in the Detail for Selected 5 Minute Interval section is automatically updated to display the selected time period.
In the example shown in Figurethe 5 -minute interval from to is selected for the CPU Used wait class. If you discover a performance problem, then you can attempt to resolve it in real time. On the Performance page, do one of the following:. Click a snapshot below the chart that corresponds to the time when the performance problem occurred to run ADDM for that time period. For information about creating snapshots manually, see "Creating Snapshots".
If one or several SQL statements are consuming a majority of the activity, then you should investigate them. On the Performance page, in the Average Active Sessions chart, click the CPU block on the chart or its corresponding wait class in the legend.