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Analyze SQL with SQL Tuning Advisor

You can use SQL Tuning Advisor to analyze and tune SQL statements.

SQL tuning is an important aspect of database system performance tuning. SQL Tuning Advisor is a mechanism for resolving problems related to sub-optimally performing SQL statements. It takes one or more SQL statements or one SQL Tuning Set (STS) as input and invokes the Automatic Tuning Optimizer to analyze the statements. The output is in the form of findings and recommendations, along with a rationale for each recommendation and its expected benefit. Tuning recommendations include the following and you can choose to accept the recommendations to complete the tuning of the SQL statements.

  • Collection of object statistics
  • Creation of indexes
  • Rewriting SQL statements
  • Creation of SQL profiles
  • Creation of SQL plan baselines

For more information on:

In Database Management, you can use SQL Tuning Advisor to analyze the SQL statements in a Managed Database.

Note

SQL Tuning Advisor is only available for Oracle Database Enterprise Edition version 12.2 and later and if the COMPATIBLE initialization parameter is set for the database, then it should match version 12.2.0 and later. For information on database compatibility, see What Is Oracle Database Compatibility? in Oracle Database Upgrade Guide.

Here are the main steps involved in using SQL Tuning Advisor in Database Management:

  1. Select the input and run SQL Tuning Advisor: The input (SQL statements or an STS) for SQL Tuning Advisor can be selected using one of the following options and submitted as a SQL tuning task:

    • Go to Performance Hub, select one or more SQL IDs on the ASH Analytics tab, and click Tune SQL.

    • Click Tune SQL in the SQL Tuning Advisor tasks section and select SQL statements or an STS. Note that to be able to select individual SQL statements as the input, the SQL statements must first be selected on the ASH Analytics tab in Performance Hub.

    • Enable automatic SQL tuning on the database. Note that Database Management does not support the automatic configuring of SQL Tuning Advisor, however, if SQL Tuning Advisor is configured to run automatically on the database, then the automatic SQL tuning task and the findings and recommendations are also displayed in Database Management. For information on how to configure SQL Tuning Advisor as an automated task, see Managing the Automatic SQL Tuning Task in Oracle Database SQL Tuning Guide.

  2. View the findings: The SQL Tuning Advisor findings are displayed in the SQL Tuning Advisor tasks section on the Managed database details page.
  3. Implement the recommendations: The SQL Tuning Advisor findings and recommendations are available on the SQL Tuning Advisor task details page and you can review this information and opt to implement the recommendations.

Role and Privileges Required to Use SQL Tuning Advisor

You require Oracle Database administrative privileges to perform the tasks in the SQL Tuning Advisor workflow. In addition, the following role and privileges must be assigned:

GRANT SELECT_CATALOG_ROLE <following privileges> TO <admin user>
  • ADVISOR
  • CREATE JOB
  • CREATE SESSION
  • SELECT ANY DICTIONARY
  • INHERIT ANY PRIVILEGES
  • ADMINISTER SQL TUNING SET TO <SQLTUNEUSER>

For more information on Oracle Database roles and privileges, see Configuring Privilege and Role Authorization in Oracle Database Security Guide.

Run SQL Tuning Advisor

As a first step, you must run SQL Tuning Advisor on selected SQL statements or an STS.

You can use one of the following options to access the Run SQL Tuning Advisor panel on the Managed database details page of the Managed Database:

  • Click Performance Hub and on the ASH Analytics tab, scroll down to the SQL IDs listed in the SQL ID by Wait Class section (default view), select one or more SQL statements, and click Tune SQL.

    Note

    Performance Hub for Managed Databases only supports the Oracle Database Enterprise Edition and the availability of Performance Hub features depends on the Oracle Database type and version, and requires certain additional privileges. For information on all the conditions that impact the use of Performance Hub for Managed Databases, see OCI: Prerequisite Conditions for Performance Hub (KB59684) in My Oracle Support.

  • Click SQL Tuning Advisor on the left pane under Resources and click Tune SQL in the SQL Tuning Advisor tasks section.

In the Run SQL Tuning Advisor panel:

  1. Enter the following details in the Task Definition section:
    1. Name: Enter a name for the SQL tuning task.
    2. Description: Optionally, enter a description for the task.
  2. Select one of the following options in the SQL section:
    • Selected SQL statements: Use this option to select and analyze the SQL statements selected in Performance Hub. Note that this option is only enabled if SQL statements are first selected on the ASH Analytics tab in Performance Hub.
    • SQL Tuning Set: Use this option to select an STS as the input to SQL Tuning Advisor. Note that STS are listed in this section only if they're first created in the database. For information on STS, see Capturing Workloads in SQL Tuning Sets in Oracle Database SQL Tuning Guide.
  3. Provide the scope of the task in the Task parameters section:
    1. Total time limit (minutes): Specify the total time SQL Tuning Advisor should spend analyzing the statement.
    2. Scope of analysis: Select the appropriate option to define the scope of the analysis.
      • Limited: SQL Tuning Advisor produces recommendations based on statistical checks, access path analysis, and SQL structure analysis. SQL profile recommendations are not generated.
      • Comprehensive: SQL Tuning Advisor carries out all the analysis it performs under the Limited scope plus SQL profiling.
  4. Select one of the available options in the Credential type drop-down list in the Credentials section to specify database credentials to connect to the Managed Database. For information on credential types, see Use Credentials to Perform Diagnostics & Management Tasks.
  5. Click Run.
The SQL tuning task is submitted to SQL Tuning Advisor.

View SQL Tuning Advisor Findings

On running SQL Tuning Advisor, you can view its findings and recommendations in Database Management.

After you run SQL Tuning Advisor on selected SQL statements or an STS, the SQL tuning task is displayed in the SQL Tuning Advisor tasks section. Note that if SQL Tuning Advisor is configured to run automatically on the database, then the automatic SQL tuning tasks are also displayed. For each of the SQL tuning tasks, you can click the Actions icon (Actions) and click the Re-run SQL tuning task option to rerun the SQL tuning task, if required.

Click the name of the SQL tuning task to go to the SQL Tuning Advisor task details page. The SQL Tuning Advisor findings and recommendations are displayed on the following tabs on the SQL Tuning Advisor task details page:

  • Summary tab: View a graphical summary of the task and the findings provided by SQL Tuning Advisor:
    • Distinct SQL statements examined: The SQL statements examined by SQL Tuning Advisor are grouped into the SQL examined with findings, SQL skipped due to errors, and SQL examined without findings categories and displayed in a donut chart. Note that if the SQL statement was executed multiple times, then only one (distinct) execution during the analysis time period is considered.
    • Benefit for SQL profile recommendations: The benefit of the SQL profile recommendations in DB time (in seconds) is displayed in bar charts. The bar charts have before and after bars, which denote the actual DB time and improved DB time respectively. If the SQL profile recommendations are provided but not implemented, then a single Potential benefit chart is displayed, if the SQL profile recommendations are implemented partially, then the Potential and Implemented benefit charts are displayed, and if the SQL profile recommendations are implemented completely, then only the Implemented benefit chart is displayed.
    • Findings with recommendations by type: The SQL Tuning Advisor findings with recommendations are categorized by type and displayed in a bar chart.
  • SQL findings tab: View the findings and implement the recommendations of SQL Tuning Advisor. You can view the list of SQL statements and the corresponding information based on the analysis done by SQL Tuning Advisor. This includes estimated performance benefit and findings with recommendations. You can select a single SQL statement to view the specific recommendations for each finding, the rationale, and the expected benefit if a recommendation is implemented. On this tab, you can use the available options to implement all SQL profile recommendations, implement a single recommendation, and compare explain plans.
  • SQL without findings tab: View the SQL statements that were skipped owing to their not being any findings or recommendations, errors, or if the task timed out.

Implement SQL Tuning Advisor Recommendations

You can create jobs to implement SQL Tuning Advisor recommendations.

To do so, go to the SQL Tuning Advisor task details page, and view the findings and recommendations of the SQL Tuning Advisor analysis on the SQL findings tab. On this tab, you can create a job to implement all SQL profile recommendations or implement a single SQL profile, index, or statistics-related recommendation, and compare explain plans. You can also view restructure SQL, alternative plan, and miscellaneous findings, however, the option to implement restructure SQL and alternative plan recommendations is not available. For information on restructure SQL and alternative plans, see SQL Structural Analysis and Alternative Plan Analysis in Oracle Database SQL Tuning Guide.


SQL Findings tab

Topics:

Implement all SQL Profile Recommendations

  1. Go to the SQL Tuning Advisor task details page and click the SQL findings tab.
  2. Click Implement all SQL profile recommendations.
  3. In the Implement all recommendations panel:
    1. Provide the following information to create a job to implement the recommendations:
      1. Name: Enter a unique name for the job.
      2. Description: Optionally, enter a description for the job.
    2. Specify task parameters:
      1. Implement the new profile with forced matching: Select to target all SQL statements that have the same text after normalizing all literal values into bind variables. Note that if a combination of literal values and bind values is used in the SQL statement, then no bind transformation occurs.
      2. Set SQL profile category: Select to specify the category in which to create the SQL profile and enter the name of the category in the Create profile in category field.
    3. Specify job parameters:
      1. Credential type: Select one of the available options to specify database credentials to connect to the Managed Database. For information on credential types, see Use Credentials to Perform Diagnostics & Management Tasks.
      2. Bucket for job output: Select the Oracle Object Storage bucket in which the job output will be stored. The Oracle Object Storage bucket can be in the same compartment as the job or in another compartment, and you must have the required Oracle Cloud Infrastructure Object Storage service permissions to select the bucket. For more information, see Additional Permissions Required to Use Diagnostics & Management.
    4. Optionally, click Show SQL to view the SQL statement that will be executed.
    5. Click Implement recommendations.
All the SQL profile recommendations will now be implemented and you can monitor this job in the Managed Database Jobs section.

To implement a single SQL profile recommendation, select a single SQL statement, scroll down to the Implement one recommendation for SQL ID: <SQL ID> section and click the Actions icon (Actions) in the SQL profile row and click Implement recommendation.

For information on SQL profiles, see About SQL Profiles in Oracle Database SQL Tuning Guide.

Implement Index Recommendation

  1. On the SQL findings tab, select a single SQL statement, scroll down to the Implement one recommendation for SQL ID: <SQL ID> section and click the Actions icon (Actions) in the Index row and click Implement recommendation.
  2. In the Implement recommendation panel:
    1. Provide the following information to create a job to implement the recommendations:
      1. Name: Enter a unique name for the job.
      2. Description: Optionally, enter a description for the job.
    2. In the Task parameters section, select the tablespace that will be used to implement the index recommendation.
    3. Specify job parameters:
      1. Credential type: Select one of the available options to specify database credentials to connect to the Managed Database. For information on credential types, see Use Credentials to Perform Diagnostics & Management Tasks.
      2. Bucket for job output: Select the Oracle Object Storage bucket in which the job output will be stored. The Oracle Object Storage bucket can be in the same compartment as the job or in another compartment, and you must have the required Oracle Cloud Infrastructure Object Storage service permissions to select the bucket. For more information, see Additional Permissions Required to Use Diagnostics & Management.
    4. Optionally, click Show SQL to view the SQL statement that will be executed.
    5. Click Implement recommendation.
The index recommendation will now be implemented and you can monitor this job in the Managed Database Jobs section.

Implement Statistics Recommendation

  1. On the SQL findings tab, select a single SQL statement, scroll down to the Implement one recommendation for SQL ID: <SQL ID> section and click the Actions icon (Actions) in the Statistics row and click Implement recommendation.
  2. In the Implement recommendation panel:
    1. Provide the following information to create a job to implement the recommendations:
      1. Name: Enter a unique name for the job.
      2. Description: Optionally, enter a description for the job.
    2. In the Task parameters section, review the statistics being considered for the implementation.
    3. Specify job parameters:
      1. Credential type: Select one of the available options to specify database credentials to connect to the Managed Database. For information on credential types, see Use Credentials to Perform Diagnostics & Management Tasks.
      2. Bucket for job output: Select the Oracle Object Storage bucket in which the job output will be stored. The Oracle Object Storage bucket can be in the same compartment as the job or in another compartment, and you must have the required Oracle Cloud Infrastructure Object Storage service permissions to select the bucket. For more information, see Additional Permissions Required to Use Diagnostics & Management.
    4. Optionally, click Show SQL to view the SQL statement that will be executed.
    5. Click Implement recommendation.
The statistics recommendation will now be implemented and you can monitor this job in the Managed Database Jobs section.

Compare Explain Plans

The Explain Plan is a statement that displays execution plans chosen by the Oracle Optimizer for SELECT, UPDATE, INSERT, and DELETE statements. A statement's execution plan is the sequence of operations Oracle performs to run the statement.

To view and compare explain plans:

  1. On the SQL findings tab, select a single SQL statement, scroll down to the Implement one recommendation for SQL ID: <SQL ID> section and click the Actions icon (Actions) in the Index or SQL profile row and click Compare explain plans.
  2. On the Compare explain plans page:
    • Compare the DB time and I/O counts in the original and new explain plans on the Profile testing results tab. This comparison is provided in a graphical view and compares metrics such as CPU time, Buffer gets, and Disk reads. Note that the Profile testing results tab is not displayed if the comparison report is not generated.
    • Compare the steps in the original execution plan and the new execution plan of the SQL statement, on the Explain plans tab. This comparison is provided in a tabular view, however, you can select Graphical explain plan in the View option drop-down list to view a graphical representation of the explain plan. In the Graphical explain plan view, click Rotate or use the mouse and touch pad to scroll across the explain plan and view the sequence of operations.
  3. Click Close to return to the SQL Tuning Advisor task details page.

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