Feeds

How to tune your Oracle database's performance

Handy 101 explainer for DBAs

  • alert
  • submit to reddit
Workshop

Make sure that your connections are stateful

Your database might be performing well, but what if your application isn't? When they access a database, applications have to make connections. The problem emerges when they make and drop a connection each time they access a table. Connections should be maintained in between each access, but sometimes – especially if an intermediary middleware program is used – this can be overlooked. It has a catastrophic effect on performance, and represents a huge win if you find an application doing this, and correct it.

Reduce serialization where necessary

Serialization happens when transactions seem to happen as though no other users were currently modifying the database, rather than happening concurrently. A little serialization might not be a bad thing, but too much will clog your system. If lots of data blocks are being serialized in the buffer, then this might be a sign that the database needs more rollback segments relative to the number of users, so that it can support multiple changes to the database at once.

Design your database I/O properly

If your application isn't causing problems, maybe your disk-based storage is. How you spread your datafiles across different physical disks can have an important effect on performance. A common mistake is to concentrate on disk space when configuring your disk architecture, rather than looking at I/O bandwidth.

You can find some important clues here in the V$SESSION EVENT row. If a session is waiting for a disk to send data to the buffer, it'll show up as either “db file sequential read” or “db file scattered read” (depending on whether you're running an index or full table scan. If you're seeing a lot of these, check your I/O bandwidth.

Check your statistics

Migration errors are a common cause of poor database performance for Oracle DBAs. If a table schema doesn't make it from a development environment to a production environment, or if it isn't transferred properly from an older version of the database, then indexes and statistics – the information about key database parameters – can go missing.

If this happens, then it can be difficult for the database to create well-performing execution plans (these are the various methods of getting data out of the database, based on structure of an SQL query).

You can avoid this by exporting the schema statistics, using Oracle's DBMS_STATS package. This gives you the ability to review, import, and export schema statistics for a database, so that the query optimizer can do its work properly.

Ultimately, optimizing Oracle database performance is a mixture of trial, error, and some informed decision making with the help of its built-in tools. There are also other, third party tools to help shift the balance even further towards informed action. Dell's Toad includes features including PL/SQL profiling, session information and performance metric display, and the ability to test PL/SQL performance under simulated user loads. It will also help to identify the heaviest SQL loads on the system.

Armed with these tools and techniques, you should be able to stay ahead of the curve when it comes to Oracle performance. Regularly tuning the database should keep it above predefined performance metrics, and keep those panicky user phone calls at bay.

The Register is running a series of Oracle DBA workshop articles in association with Dell Software. Interested in learning more? Check out Dell whitepapers.

More from The Register

next story
Apple fanbois SCREAM as update BRICKS their Macbook Airs
Ragegasm spills over as firmware upgrade kills machines
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Captain Kirk sets phaser to SLAUGHTER after trying new Facebook app
William Shatner less-than-impressed by Zuck's celebrity-only app
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
EU dons gloves, pokes Google's deals with Android mobe makers
El Reg cops a squint at investigatory letters
Chrome browser has been DRAINING PC batteries for YEARS
Google is only now fixing ancient, energy-sapping bug
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.