In the complex world of Oracle database applications, achieving optimal performance and stability is a constant challenge. Fortunately, Oracle provides powerful tools like SQL Profiles and SQL Plan Baselines that can significantly enhance performance optimization efforts. Just as turning on the air conditioner on a hot day provides a comfortable driving experience, harnessing these capabilities can unlock the full potential of your Oracle applications. After all, if you never turn on the air conditioner, you’ll never experience its benefit. Achieving optimal performance and stability in your Oracle database applications involves making the most of the available resources and tools at your disposal. Let's explore why it's essential to consider the intelligent use of SQL Profiles and SQL Plan Baselines, and evaluate their impact before embarking on extensive application redesigns.
SQL Profiles and SQL Plan Baselines offer tangible benefits that can transform the performance and stability of your Oracle applications. By utilizing these capabilities, you can achieve improved plan stability, enhanced query performance, reduced resource consumption, and better scalability. They provide an opportunity to fine-tune and optimize your application's execution plans, ensuring a smoother and more efficient operation.
Again, before investing significant resources in application redesigns, it's prudent to evaluate the impact of SQL Profiles and SQL Plan Baselines. By incorporating these capabilities into your performance optimization strategy, you can assess their effectiveness in achieving the desired plan stability and performance improvements. This evaluation allows you to make informed decisions based on observed results rather than embarking on extensive redesigns right from the start.
What are SQL Profiles and SQL Plan Baselines?
SQL Profiles and SQL Plan Baselines are features of Oracle that contribute to performance optimization in Oracle databases.
SQL Profiles:
A SQL Profile is a mechanism [extra cost option with the Diagnostics and Tuning Pack] that Oracle uses to provide additional information to the optimizer, helping it generate more efficient execution plans for SQL queries. They influence the optimizer's decisions by providing hints, statistics, and other metadata to guide the query optimization process. Most often, SQL Profiles are generated by the SQL Tuning Advisor (STA) [i.e. running the optimizer in tuning mode] if the STA finds a better execution plan, but they can also be manually generated for an existing SQL Plan Hash Value. SQL Profiles provide for data dictionary persisted hints that (mostly) adjust cardinality misestimates that occur during SQL statement optimization. SQL Profiles offer a “force matching” capability so that they can apply to SQL statements that only differ by say hard coded subset conditions. The cardinality estimate corrections embedded in a SQL Profile are not good forever as actual cardinalities may change over time which could result in a better execution plan on down the road, basically a SQL Profile does not fully constrain the execution plan and they are not designed to evolve on their own over time [as are “baselines”].
SQL Plan Baselines:
SQL Plan Baselines [available in Oracle’s Enterprise Edition] are a collection of execution plans for SQL statements, which, if excepted, can be used to direct the optimizer to known good execution plans. Baselines are a component in a larger framework called SQL Plan Management. They are intended to proactively prevent regression of SQL performance by serving as a reference or baseline for the optimizer to maintain stable and consistent execution plans over time. SQL Plan Baselines allow you to capture and lock in a preferred execution plan for a specific SQL statement, preventing plan regressions and maintaining desired performance. One big difference compared to SQL Profiles is that the execution plan must already exist in the database in order to create a baseline for it, whereas a SQL Profile (i.e. more efficient new execution plan) can be generated by the SQL Tuning Advisor. Another big difference is that the accepted baselines can “evolve” over time [this is a bigger topic that falls under SQL Plan Management].
Hints as an alternative to SQL Profiles or SQL Plan Baselines:
Hints hard coded in a SQL statement will influence the optimizer but still not guarantee an execution plan, using SQL Plan Management (SPM) is going to be a better alternative as a tuning option. Rationale: SPM is a declarative mechanism (i.e. a no code mechanism that is enforced by the DBMS) to create and maintain execution plan stability and can pick up new tunings due to schema changes such as adding a more efficient index.
Since the SQL Plan baselines are intended as proactive stabilizing of execution plans [i.e. issue prevention], this mechanism tends to be the preferred mechanism [over SQL Profiles which are usually used for issue resolution]. Having said that these two mechanisms are not mutually exclusive and can be used to work together, where a SQL Profile is used to fix a problem and is later turned into a SQL Plan Baseline and the SQL Profile dropped or disabled. In this way, if a better execution plan comes up in the future, this new better plan can be used as the accepted baseline. If you think creatively about SQL Profiles or SQL Plan Baselines you have a lot of flexibility using these approaches.
Harnessing SQL Profiles and SQL Plan Baselines:
In the complex realm of Oracle database performance tuning, one topic continues to spark intense debates [in some corners]: the usage of SQL Profiles and SQL Plan Baselines. These powerful tools offer the potential to stabilize execution plans and resolve performance issues efficiently. However, conflicting opinions among DBAs and developers often hinder the adoption of these capabilities.
As application teams strive for scalability, optimal performance, and cost-effectiveness, it becomes necessary to explore intelligent utilization of SQL Profiles and SQL Plan Baselines. Despite the complex nature of the Oracle Optimizer and the challenges posed by intricate application environments, these features can offer viable and sticky solution sets. They provide an alternative to time-consuming code changes and application modifications, saving valuable resources and lengthy development cycles.
In support of the use of SQL Profiles and SQL Plan Baselines many renowned Oracle experts (e.g. Carlos Sierra and Nigel Bayliss) drawing from their extensive experience and successful implementations, strongly advocate for the intelligent use of these capabilities. Their insights shed light on the tangible benefits these features can bring to performance optimization and application stability.
However, some DBAs express reservations about adopting SQL Profiles and SQL Plan Baselines, citing concerns about potential side effects, increased complexity, and manageability challenges. To foster a productive discussion and bridge the gap, collaboration between application teams and DBAs is crucial.
We can bring the developer and DBA sides together by initiating education and knowledge-sharing initiatives, conducting joint performance analyses, and implementing pilot projects, which will hopefully build consensus on the topic. Also, establishing guidelines that outline the appropriate usage of SQL Profiles and SQL Plan Baselines can help overcome resistance and ensure consistent and effective implementations.
In an ever-evolving landscape, where application scalability, optimization, and cost-effectiveness are paramount, it is essential to explore the possibilities offered by SQL Profiles and SQL Plan Baselines. By embracing these capabilities and encouraging collaboration between developers and DBAs, organizations can unlock the full potential of Oracle performance tuning and drive their applications towards unparalleled efficiency and stability.
When considering these capabilities, I’d like to recall to mind the metaphor I introduced earlier of driving a car with an air conditioner on a hot day and never turning the AC on. While you may want to conserve gas by keeping the AC off, if you have the need for AC, you should know that the capability is there, but if you never use the capability, you’ll never experience the benefit. My recommendation is to use these capabilities and see if you are getting the plan stability and performance you expect before going into redesign of the application. If they earn their value you can choose to continue using them or not.
Human/Social Challenges with SQL Profiles and SQL Plan Baselines:
While the technical aspects of implementing SQL Profiles and SQL Plan Baselines are important, there can also be social or human impediments to achieving success with these features. Here are some social or human factors that can affect their effectiveness:
Existing optimization approaches: DBAs might have established optimization techniques or methodologies that they are accustomed to and have been using successfully (e.g. preferring a more hands-on approach to query optimization, relying on their expertise and manual interventions to fine-tune execution plan). Introducing SQL Profiles and SQL Plan Baselines might require a shift in their approach, which can be met with skepticism or resistance. In such cases, it's important to demonstrate the complementary nature of these capabilities and how they can augment existing optimization strategies, rather than replacing them entirely. Also, building trust by showcasing successful implementations and highlighting the flexibility and control that DBAs still have over these features can help alleviate their concerns.
Control and risk concerns: DBAs often have the responsibility of managing and maintaining the performance of the database environment. Introducing SQL Profiles and SQL Plan Baselines, which can impact query optimization and execution plans, may be seen as an additional risk. DBAs might be concerned about losing control over the optimization process or fear that the automated nature of these features might lead to unintended consequences. Addressing these concerns by highlighting the benefits, providing proper documentation, and involving DBAs in the decision-making process can help alleviate their apprehensions.
Resource limitations: DBAs often face resource constraints, such as time and personnel, which can limit their ability to explore and implement new optimization techniques. Introducing SQL Profiles and SQL Plan Baselines might be perceived as an additional burden in terms of learning, implementation, and maintenance. Addressing resource concerns by showcasing the potential time and resource savings that can be achieved in the long run with these features can help alleviate the resistance.
Resistance to change: People generally have a natural resistance to change, especially when it comes to established processes or ways of doing things. Introducing SQL Profiles and SQL Plan Baselines may disrupt existing practices and require teams to adopt new approaches. Resistance to change from stakeholders, such as developers, DBAs, or management, can impede the successful adoption and utilization of these features.
Lack of awareness or understanding: Some teams may not be fully aware of the benefits and capabilities of SQL Profiles and SQL Plan Baselines. Lack of knowledge or understanding about how these features work and their potential impact on performance optimization can lead to hesitation or reluctance in using them effectively. Proper education, training, and communication are essential to address this impediment.
Siloed organizational structure: In organizations with siloed or fragmented structures, collaboration between different teams (e.g., application teams, DBAs, performance analysts) may be limited. The success of SQL Profiles and SQL Plan Baselines often requires close collaboration and coordination among these teams. Overcoming silos and promoting cross-functional collaboration can help address this impediment.
Communication gaps: Poor communication between application teams and DBAs can hinder the effective utilization of SQL Profiles and SQL Plan Baselines. Misalignment of goals, lack of clear communication channels, or insufficient information sharing can lead to misunderstandings, delays, or misalignment in implementing and maintaining these features.
Lack of ownership or responsibility: Without clear ownership or responsibility assigned to the management and execution of SQL Profiles and SQL Plan Baselines, these features may not receive the necessary attention or priority. Unclear roles and responsibilities can lead to gaps in maintenance, monitoring, and optimization efforts.
Organizational culture and politics: Organizational culture and politics can also impact the success of SQL Profiles and SQL Plan Baselines. In some cases, internal politics, power dynamics, or conflicting priorities may influence decision-making and hinder the adoption or effective use of these features. Building a culture of collaboration, transparency, and a shared focus on performance optimization can help address this impediment.
By recognizing and addressing these social or human impediments, organizations can create an environment conducive to the successful implementation and utilization of SQL Profiles and SQL Plan Baselines. Encouraging open communication, providing education and training, fostering cross-functional collaboration, and establishing clear ownership and responsibility can help overcome these challenges.
Intelligent Use of Profiles and Baselines Reduces Infrastructure Costs:
Effective utilization of SQL Profiles and SQL Plan Baselines not only helps lower application development and support costs but can also have a significant impact on overall infrastructure costs creating a win-win situation for organizations.
When performance issues are addressed efficiently using these tools, databases and applications can operate in a more optimized manner. This optimization leads to reduced resource consumption, allowing organizations to gain back valuable headroom in terms of system capacity. By fine-tuning the execution plans and improving query performance, the workload on the database and associated infrastructure can be minimized, leading to better scalability and resource utilization.
The benefits of reduced infrastructure costs extend beyond monetary savings. Organizations can avoid costly hardware upgrades or additions by achieving optimal performance with their existing infrastructure. By harnessing the power of SQL Profiles and SQL Plan Baselines, application teams can maximize the efficiency of their database resources, leading to improved scalability and a more cost-effective infrastructure.