The SQL Access Advisor makes suggestions about indexes and materialized views which might improve system performance. This article describes how to use the SQL Access Advisor in Oracle 10g.
Related articles.
Enterprise Manager
The SQL Access Advisor is accessible from Enterprise Manager. Specific reports can be produced by clicking on the "Advisor Central" link, then the "SQL Access Advisor" link. The resulting page allows you to create a workload and a SQL Access Advisor task. Once the task has completed you can view information about the findings and recommendations.
DBMS_ADVISOR
The DBMS_ADVISOR package can be used to create and execute any advisor tasks, including SQL Access Advisor tasks. The following example shows how it is used to create, execute and display a typical SQL Access Advisor script for the current workload.
DECLARE
l_taskname VARCHAR2(30) := 'test_sql_access_task';
l_task_desc VARCHAR2(128) := 'Test SQL Access Task';
l_wkld_name VARCHAR2(30) := 'test_work_load';
l_saved_rows NUMBER := 0;
l_failed_rows NUMBER := 0;
l_num_found NUMBER;
BEGIN
-- Create a SQL Access Advisor task.
DBMS_ADVISOR.create_task (
advisor_name => DBMS_ADVISOR.sqlaccess_advisor,
task_name => l_taskname,
task_desc => l_task_desc);
-- Reset the task.
DBMS_ADVISOR.reset_task(task_name => l_taskname);
-- Create a workload.
SELECT COUNT(*)
INTO l_num_found
FROM user_advisor_sqlw_sum
WHERE workload_name = l_wkld_name;
IF l_num_found = 0 THEN
DBMS_ADVISOR.create_sqlwkld(workload_name => l_wkld_name);
END IF;
-- Link the workload to the task.
SELECT count(*)
INTO l_num_found
FROM user_advisor_sqla_wk_map
WHERE task_name = l_taskname
AND workload_name = l_wkld_name;
IF l_num_found = 0 THEN
DBMS_ADVISOR.add_sqlwkld_ref(
task_name => l_taskname,
workload_name => l_wkld_name);
END IF;
-- Set workload parameters.
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'ACTION_LIST', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'MODULE_LIST', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'SQL_LIMIT', DBMS_ADVISOR.ADVISOR_UNLIMITED);
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'ORDER_LIST', 'PRIORITY,OPTIMIZER_COST');
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'USERNAME_LIST', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_sqlwkld_parameter(l_wkld_name, 'VALID_TABLE_LIST', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.import_sqlwkld_sqlcache(l_wkld_name, 'REPLACE', 2, l_saved_rows, l_failed_rows);
-- Set task parameters.
DBMS_ADVISOR.set_task_parameter(l_taskname, '_MARK_IMPLEMENTATION', 'FALSE');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'EXECUTION_TYPE', 'INDEX_ONLY');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'MODE', 'COMPREHENSIVE');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'STORAGE_CHANGE', DBMS_ADVISOR.ADVISOR_UNLIMITED);
DBMS_ADVISOR.set_task_parameter(l_taskname, 'DML_VOLATILITY', 'TRUE');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'ORDER_LIST', 'PRIORITY,OPTIMIZER_COST');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'WORKLOAD_SCOPE', 'PARTIAL');
DBMS_ADVISOR.set_task_parameter(l_taskname, 'DEF_INDEX_TABLESPACE', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_task_parameter(l_taskname, 'DEF_INDEX_OWNER', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_task_parameter(l_taskname, 'DEF_MVIEW_TABLESPACE', DBMS_ADVISOR.ADVISOR_UNUSED);
DBMS_ADVISOR.set_task_parameter(l_taskname, 'DEF_MVIEW_OWNER', DBMS_ADVISOR.ADVISOR_UNUSED);
-- Execute the task.
DBMS_ADVISOR.execute_task(task_name => l_taskname);
END;
/
-- Display the resulting script.
SET LONG 100000
SET PAGESIZE 50000
SELECT DBMS_ADVISOR.get_task_script('test_sql_access_task') AS script
FROM dual;
SET PAGESIZE 24
The value for the SET LONG command should be adjusted to allow the whole script to be displayed.
Quick Tune
If you just want to tune an individual statement you can use the QUICK_TUNE procedure as follows.
BEGIN
DBMS_ADVISOR.quick_tune(
advisor_name => DBMS_ADVISOR.SQLACCESS_ADVISOR,
task_name => 'emp_quick_tune',
attr1 => 'SELECT e.* FROM emp e WHERE UPPER(e.ename) = ''SMITH''');
END;
/
Any recommendations can then be displayed using the previous query with the correct task name specified.
Related Views
The following views can be used to display the SQL Access Advisor output without using Enterprise Manager or the get_task_script function:
- DBA_ADVISOR_TASKS
- Basic information about existing tasks. - DBA_ADVISOR_LOG
- Status information about existing tasks. - DBA_ADVISOR_FINDINGS
- Findings identified for an existing task. - DBA_ADVISOR_RECOMMENDATIONS
- Recommendations for the problems identified by an existing task.
For more information see:
Hope this helps. Regards Tim...
