Cognitive Computing Authors: Pat Romanski, Yeshim Deniz, Liz McMillan, Elizabeth White, Jason Bloomberg

Related Topics: Recurring Revenue, Java IoT, Machine Learning

Recurring Revenue: Article

How to Monitor Oracle Database Performance

What metrics are we interested in?

An Oracle database provides several v$ views to query information about the database instance, including statistical information that can be used for monitoring and problem analysis purposes. Rene Nyffenegger wrote a nice Summary on Oracle’s v$ views that gives an overview of all available views.

The following illustration shows a dashboard with key metrics that we pull out from an Oracle database when doing performance management with our clients:

dynaTrace Dashboard showing key performance metrics queried from an Oracle Database via v$ tables

dynaTrace Dashboard showing key performance metrics queried from an Oracle Database via v$ tables

In this article I provide a quick overview on what these metrics tell us and how to get them. If you run dynaTrace in your environment you can also download the [DL:Oracle Monitor Plugin] from our Community Portal .

I also appreciate feedback from all Oracle experts out there. I am sure there are many more metrics that are interesting and important for performance analysis, so please add those here.

What metrics are we interested in?
Every time you start up an Oracle instance the system allocates memory for its System Global Area (SGA) (Read more on Oracle SGA Concepts). A very interesting area involves internal data buffers. These buffers hold data in memory and are first searched when a request comes in before fetching data from disk. Buffering obviously saves on I/O and speeds up database requests. There is a great article that explains the different buffer pools, how they can be configured and it also gives recommendations on sizing: Using the dynamic SGA Features of Oracle 9i.

Buffer, Execution and I/O metrics
There are several great blogs that explain metrics such as Buffer Cache Hit Ratio, In Memory Sort Ratio,Parse to Execute Ratio or talk about I/O metrics and how to tune your database based on metrics retrieved from v$buffer_pool_statistics.

The metrics that we query therefore are Buffer Cache Hit Ratio, In Memory Sort Ratio, Parse to Execute Ratio, SQL Area Get Ratio, Buffer Busy Wait, Free Buffer Waits, Write Complete Wait, Consistent Gets, DB Block Gets and Physical Reads.

Connection and User Count
The number of connections and user sessions are key system and performance indicators. The number of connections is usually configurable via connection pool settings on the application server. The more connections the more resources you need on the database - on the other hand you can serve more concurrent users that request data from the database. The blog v$license view tipsgives a good overview of values exposed by this view.

The metrics that we query from this view are Maximum Concurrent User Sessions, Current Concurrent User Sessions, Highest Concurrent User Sessions and Maximum Named Users

Connection Time
Additionally to the metrics that we query from the system tables, we also monitor how long it takes to actually establish a physical connection to the database. Our monitors use the Oracle Database driver and measure the time it takes to get a connection. This metric gives us a good indication on how good the database can deal with new incoming connection requests.

How to query them
Querying these values is pretty straight forward. [Our monitor] is implemented in Java. We load the Oracle JDBC Driver and establish a connection to the Oracle Database Instance when we initially launch the monitor. Check out the following blog with an example on How To connect to Oracle with JDBC. Then we simply execute the SQL statements to retrieve the actual measures on a scheduled interval (e.g.: every 30 seconds).

Most of the statements we execute are explained in the blogs I linked to earlier in this article, e.g.: Buffer Cache Hit Ratio, In Memory Sort Ratio,Parse to Execute Ratio

How to run a monitor and how to read the values
We run our monitors on the dynaTrace APM Platform . This means that these monitors are executed on a scheduled interval, e.g.: every 30 seconds. A monitor itself is a Java OSGI plugin with an execute method that queries and returns the metrics from the database views. The monitored values can then be displayed in a dashboard (as seen in the screenshot in the top) or can trigger alerts, e.g.: notify my admins in case Buffer Cache Ratio drops under a defined threshold.

If you implement your own monitor you need to figure out how granular you need the data and you have to figure out how to display and process the individual measure points.

How to read these values?
The most important thing to understand is to not only look at individual metrics but really look at your system - and with that I mean looking at measures from all application components that are involved to process individual transactions. A low Buffer Cache Hit Ratio doesn't mean that your DBA's should run off right away trying to increase this value by tweaking the db_cache_size. The business function of the application largely dictates the way it interacts with its backend datastore.  For example, if the application is more Decision Support oriented, effective use of the Buffer Cache may be impractical or impossible due to the large data sets that are being analyzed.  On the other hand, if the application is OLTP oriented, the Buffer Cache should be highly utilized and the behaviour of the Hit Ratio with respect to transaction mixes, peak concurrencies, etc ... becomes a critical measure to understand.  Nonetheless, even in these cases, you need to look at overall Transaction Response Times and see if you actually have a problem that affects the end-user.

If that is the case you need to figure out whether the time is spent in the Application Layer (bad performing code), the Network (too much data being sent between components) or the Database (inefficient settings or non optimized indices, ...). If it turns out that the problem is mainly caused by the Database Layer you can check whether your connection pools are exhausted. If that is the case you actually want to talk with the application developers and see whether they can optimize the usage of connections. If you have too much traffic on the network because too much data is requested from the database you want to look into optimizing the application code to really only query the data that is needed. If it then turns out that the problem is on the database you have to observe the metrics discussed in this article. There are ways to tweak database settings to improve buffer usage. I am not the expert on Oracle but if you follow the links that I've posted throughout you will find many good recommendations on what to do in various scenarios.

The database is most often not the root cause of transactions that perform poorly from and end-user’s perspective. Too often it is the application that is e.g.: keeping connections open for too long or is querying more data than needed. I recommend reading Top 10 Performance Problems taken from Zappos, Monster, Thomson and Co. Problem Patterns #1, #4 and #7 often lead people to point to the DBA's first instead of identifying these problems in the application layer. That being said - there are of course scenarios where it really is the database that slows down transaction response times. And in these cases it is important to have enough information available to analyze the root cause of the problem. Correlating the database metrics with other metrics from the underlying operating system, network, application server, web server, ... will make it easier to find a solution to your performance problems.

What's your strategy on database monitoring?
This is one example on monitoring your database. I am interested in getting your feedback on which tools and approaches you use to monitor your Oracle, SQL-Server, MySql, ... databases. Let us know (via comments - login required) which measures you monitor and you consider important. Thanks

Related reading:

  1. Lessons Learned: How we Monitor our Community Portal from the Cloud Our dynaTrace Community Portal is our gateway to our users....
  2. Apache Web Server Status Monitoring with a dynaTrace Plugin provided by MCG Systems The extensible plugin architecture of dynaTrace opens many doors for...
  3. Automated Performance Analysis: What’s going on in my ASP.NET or ASP.NET MVC Application? I’ve spent some time in the last weeks playing with different...

More Stories By Andreas Grabner

Andreas Grabner has been helping companies improve their application performance for 15+ years. He is a regular contributor within Web Performance and DevOps communities and a prolific speaker at user groups and conferences around the world. Reach him at @grabnerandi

IoT & Smart Cities Stories
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Druva is the global leader in Cloud Data Protection and Management, delivering the industry's first data management-as-a-service solution that aggregates data from endpoints, servers and cloud applications and leverages the public cloud to offer a single pane of glass to enable data protection, governance and intelligence-dramatically increasing the availability and visibility of business critical information, while reducing the risk, cost and complexity of managing and protecting it. Druva's...
BMC has unmatched experience in IT management, supporting 92 of the Forbes Global 100, and earning recognition as an ITSM Gartner Magic Quadrant Leader for five years running. Our solutions offer speed, agility, and efficiency to tackle business challenges in the areas of service management, automation, operations, and the mainframe.
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, compared the Jevons Paradox to modern-day enterprise IT, examin...
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, @CloudEXPO and DXWorldEXPO are two of the most important technology events of the year. Since its launch over eight years ago, @CloudEXPO and DXWorldEXPO have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, we provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading...
DSR is a supplier of project management, consultancy services and IT solutions that increase effectiveness of a company's operations in the production sector. The company combines in-depth knowledge of international companies with expert knowledge utilising IT tools that support manufacturing and distribution processes. DSR ensures optimization and integration of internal processes which is necessary for companies to grow rapidly. The rapid growth is possible thanks, to specialized services an...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Scala Hosting is trusted by 50 000 customers from 120 countries and hosting 700 000+ websites. The company has local presence in the United States and Europe and runs an internal R&D department which focuses on changing the status quo in the web hosting industry. Imagine every website owner running their online business on a fully managed cloud VPS platform at an affordable price that's very close to the price of shared hosting. The efforts of the R&D department in the last 3 years made that pos...