While upgrading the Oracle database or making any changes in the system parameters, you might have noticed that some SQLs’ performance or queries get highly regressed. If this happens, then don’t worry it’s quite obvious and will always happen whenever there are any changes in the plan. But you can prevent this regression if you use SQL Plan Management Oracle.
In case you aren’t aware of what it is and how it can help, then this blog is surely meant for you. In this blog, we are going to cover every basic aspect related to the SQL plan management and that how it will help in preventing query or performance regression.
An Overview of SQL Plan Management Oracle
SQL Plan Management is a deterrent tool that allows the optimizer to manage SQL execution plans automatically while ensuring that only verified and known plans are used by the database.
SQL plan management uses a mechanism that lets the optimizer to use it for a SQL statement. This mechanism is known as a SQL Plan baseline. It’s a set of accepted plans. A plan is typically known to hold all plan-related information such as a set of hints, SQL plan identifier, optimizer environment, and bind values.
The optimizer uses this information for reproducing an execution plan. Commonly, the database accepts a plan into the plan baseline only after it verifies and confirms that the plan performs absolutely well.
In short, a SQL Plan management Oracle is a tool used for mitigating the risk of query regression when you upgrade to Oracle Database11g or 12c.
Key Components of SQL Plan Management
Mainly, there are three essential elements of SQL Plan management. They are as follows:
- SQL Plan Baseline Capture
The component creates a SQL plan baselines that describes the accepted or trusted execution plan for all relevant SQL statements. If you aren’t sure where you can find the SQL plan baselines, then let us tell you that you can find the plan baselines stored in a plan history in the SQL Management Base. The management base will be found in the SYSAUX tablespace.
- SQL Plan Baseline Selection
SQL Plan baseline selection makes sure that the tool uses only the accepted execution plans for statements that have a SQL plan baseline. Furthermore, it ensures that it tracks every new execution plan in the plan history for a statement. The plan history comprises both unaccepted and accepted plans. An unaccepted plan can either be rejected (verified but not performant) or unverified (newly found but not verified).
- SQL Plan Baseline Evolution
This component is meant to assess every unverified execution plan for a given statement in the plan history for either to be accepted or rejected.
What’s the Main Purpose of SQL Plan Management?
SQL plan management oracle restricts performance or query regression due to any plan changes in the database. Secondly, this tool aims at gracefully adapting to changes.
It must be noted that if an event has caused any irreversible execution plan changes such as dropping an index, SQL plan baseline cannot help in this case.
Advantages of SQL Plan Management Oracle
SQL plan management can preserve or improve SQL performance in database systems and upgrades and data changes.
Some more specific benefits comprise the following-
- When a database upgrade causes the installation of a new optimizer version, it usually results in plan changes for a small part of SQL statements. Due to plan changes, either the performance of the system improves or there isn’t any change literally. However, in some cases, plan changes result in performance regression and here’s where SQL plan baselines come into play. It significantly lessens potential regressions that result from an upgrade.
- Ongoing data and system changes can have an impact on plans for some SQL statements potentially creating performance regressions. Plan baselines assist in reducing this performance regression. Further, it stabilizes the SQL performance of the system as well as the database.
- Employing new application modules brings in new SQL statements into the database. The application software is likely to use the proper SQL execution plan that’s developed in a standard test configuration for the new statements. In case the system configuration differs from the test configuration, then the database can develop SQL plan baselines over time to produce better performance.
In the Bottom Line
During an automated or manual updating of statistics for some objects or while changing some parameters related to the optimizer, or any changes made in the system cause a drastic change in the execution plan. Even more dramatic change is noticed while a database is upgraded. While most plans lead to improvement as they are made to adapt to the new system environment, there are some that lead to performance regression as well. In such cases, we need a SQL plan management mechanism whose main work is to reduce the regression risk.
If you are stuck with long queries or if your system’s performance has reduced, you can get a SQL query optimization tool online. Tosska Technologies Limited is one such company that provides solutions and tools related to database and SQL related performance optimization and improvements. We use advanced technologies like AI (artificial intelligence) so that our tool can help you solve numerous tasks at a time.