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7/22/2019 SQL Tuning Advisor in Oracle SQL Developer
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SQL Tuning Advisor in Oracle SQL Developer 3.2
SQL Tuning Advisor in Oracle SQL Developer 3.2Topic List Collapse All TopicsHide All Images Print
Overview
Purpose
This tutorial shows you how to use the SQL Tuning Advisor feature in Oracle SQL Developer 3.2.
Time to Complete
Approximately 40 minutes
Introduction
The SQL Tuning Advisor analyzes high-volume SQL statements and offers tuning recommendations. Ittakes one or more SQL statements as an input and invokes the Automatic Tuning Optimizer to perform SQLtuning on the statements. It can run against any given SQL statement. The SQL Tuning Advisor providesadvice in the form of precise SQL actions for tuning the SQL statements along with their expectedperformance benefits. The recommendation or advice provided relates to the collection of statistics onobjects, creation of new indexes, restructuring of the SQL statement, or creation of a SQL profile. You canchoose to accept the recommendation to complete the tuning of the SQL statements.
Oracle Database can automatically tune SQL statements by identifying problematic SQL statements andimplementing tuning recommendations using the SQL Tuning Advisor. You can also run the SQL Tuning
Advisor selectively on a single or a set of SQL statements that have been identified as problematic.
In this tutorial, you learn how to run and review the recommendations of the SQL Tuning Advisor.
Note: Tuning Advisor is part of the Tuning Pack, one of the Oracle management packs and is available for
purchase with Enterprise Edition. For more information see The Oracle Technology Network or the onlinedocumentation.
Hardware and Software Requirements
The following is a list of hardware and software requirements:
o Oracle Database 11g Enterprise Edition with access to the Tuning and Diagnostic managementpacks and with the sample schema installed.
o Oracle SQL Developer 3.2.
Prerequisites
o Download Oracle SQL Developer 3.2 here.
Note: For best results, use Firefox or Chrome browsers to view this tutorial.
Creating a Database Connection
The first step to managing database objects using Oracle SQL Developer 3.2 is to create a databaseconnection.
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Perform the following steps to create a database connection:
Note: If you already have database connections for HR and SYSTEM, you do not need to perform the
following steps. You can move to Providing Privileges to the Hr User topic.
If you have installed the SQL Developer icon on your desktop, click the icon to start your SQL Developerand move to Step 4. If you do not have the icon located on your desktop, perform the following steps to
create a shortcut to launch SQL Developer 3.2 from your desktop.
Open the directory where the SQL Developer 3.2 is located, right-click sqldeveloper.exe (on Windows) orsqldeveloper.sh (on Linux) and select Send to > Desktop (create shortcut).
On the desktop, you will find an icon named Shortcut to sqldeveloper.exe. Double-click the icon to open SQLDeveloper 3.2.
Note: To rename it, select the icon and then press F2 and enter a new name.
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Your Oracle SQL Developer opens up.
In the Connections navigator, right-click Connections and select New Connection.
The New / Select Database Connection dialog opens. Enter the connection details as follows and click Test.
Connection Name: system
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Username: system
Password: <your_password >(Select Save Password)
Hostname: localhost
SID: <your_own_SID>
Check for the status of the connection on the left-bottom side(above the Help button). It should readSuccess. Click Save and then click Connect.
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In the Connections navigator, to create a new connection to the hr schema, right-click Connections andselect New Connection.
The New / Select Database Connection dialog opens. Enter the connection details as follows and click Test.
Connection Name: hr
Username: hr
Password: <your_password >(Select Save Password)
Hostname: localhost
SID: <your_own_SID>
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Check for the status of the connection on the left-bottom side(above the Help button). It should readSuccess. Click Save and then click Connect.
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Providing Privileges and Removing the Existing Statistics on the HR User
A user requires certain privileges to run the SQL Tuning Advisor. Also, in order to collect and managestatistics on the HR schema, the existing statistics need to be cleared. Below are the steps to grant SQLTuning Advisor privileges and to remove the existing statistics on the hr user.
Click SQL Worksheet and select system user.
To grant privileges to the hr user to run the SQL Tuning Advisor, enter the following lines of code. Click RunScript.
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grant advisor to hr;grant administer sql tuning set to hr;
The output for the statements is displayed.
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The Oracle database allows you to collect statistics of many different kinds in order to improve performance.To illustrate some of the features the SQL Tuning Advisor offers, clear the existing statistics from the HRschema.
To delete the schema statistics, enter the following line of code.
exec DBMS_STATS.DELETE_SCHEMA_STATS ('hr');
Select the statement and click Run Statement
With the DBMS_STATS package you can view and modify optimizer statistics gathered for database
objects.The DELETE_SCHEMA_STATS procedure deletes statistics for an entire schema.
The outputs for the statements are displayed.
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Running the SQL Tuning Advisor on a SQL statement
In this topic, you run the SQL Tuning Advisor on a SQL statement. Four types of analysis are performed bythe SQL Tuning Advisor on the SQL statement.
All the recommendations are displayed in the Overview. You can also view each recommendationindividually.
Open the SQL Worksheet for the hr user by clicking SQL Worksheet.
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Enter the following SQL statement in the worksheet.select sum(e.salary), avg(e.salary), count(1), e.department_id from departmentsd, employees e group by e.department_id order by e.department_id;
Select the SQL statement and click SQL Tuning Advisor .
The SQL Tuning Advisor output appears.
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In the left navigator, click Statistics. In this analysis, objects with stale or missing statistics are identified andappropriate recommendations are made to remedy the problem.
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In the left navigator, click SQL Profile. Here, the SQL Tuning Advisor recommends to improve the executionplan by the generation of a SQL Profile.
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Click the Detail tabbed page to view the SQL Profile Finding.
In the left navigator, click Indexes. This recommends whether the SQL statement might benefit from an
index. If necessary, new indexes that can significantly enhance query performances are identified andrecommended.
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Click the Overview tabbed page. In this case, there are no index recommendations.
In the left navigator, click Restructure SQL. In this analysis, relevant suggestions are made the restructureselected SQL statements for improved performance.
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Implementing SQL Tuning Advisor Recommendations
You can implement the SQL Tuning Advisor recommendation feature. This will enable you to update thestatistics in hr schema. Perform the following steps to implement the SQL Tuning Advisor recommendations:
In the Connections navigator, right-click hr and select Gather Schema Statistics....
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In Gather Schema Statistics, select Estimate Percent as 100 from the drop-down list so that all rows ineach table are read. This ensures that the statistics are as accurate as possible.
Click Apply.
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A confirmation message appears. Click OK.
To run the SQL Tuning Advisor on the SQL statement again, select the SQL statement and click SQLTuning Advisor.
The SQL Tuning Advisor output appears. By gathering statistics, the Statistics and SQL Profile advice isnow removed.
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In the left navigator, click each of the SQL Tuning Advisor Implement Type to check if all therecommendations have been implemented.
Note the issues reported to you:
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Note the issues reported to you:
Note that the Restructure SQL recommendation to remove an unused table remains.
Remove the "departments" table in the SQL statement and click SQL Advisor.
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select sum(e.salary), avg(e.salary), count(1), e.department_id fromemployees egroup by e.department_id order by e.department_id;
The output appears. All of the advice recommendations have been removed.
Summary
In this tutorial, you have learned how to:
o Create a Database Connectiono Provide Privileges to the HR Usero Run the SQL Tuning Advisor on a SQL statemento Implement SQL Tuning Advisor Recommendations
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Credits
o Lead Curriculum Developer: Dimpi Sarmah, Sharon Stepheno Other Contributors: Ashley Chen, Swarnapriya Shridhar, Nancy Greenberg
Help OLL About Oracle Contact Us Terms of Use
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Overview
Creating a Database Connection
Providing Privileges and Removing the Existing Statistics on the HR User
Running the SQL Tuning Advisor on a SQL statement
Implementing SQL Tuning Advisor Recommendations
Summary
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