The DBMS_SPM
package supports the SQL plan management feature by providing an interface for the DBA or other user to perform controlled manipulation of plan history and SQL plan baselines maintained for various SQL statements.
See Also:
For more information about "Using SQL Plan Management" in the Oracle Database SQL Tuning GuideThis chapter contains the following topics:
Overview
Security Model
Constants
Examples
The DBMS_SPM
package allows the user to manage SQL execution plans using SQL plan management. SQL plan management prevents performance regressions resulting from sudden changes to the execution plan of a SQL statement by recording and evaluating the execution plans of SQL statements over time, and builds SQL plan baselines composed of a set of existing plans known to be efficient. The SQL plan baselines are then used to preserve performance of corresponding SQL statements, regardless of changes occurring in the system. Common usage scenarios where SQL plan management can improve or preserve SQL performance include:
A database upgrade that installs a new optimizer version usually results in plan changes for a small percentage of SQL statements, with most of the plan changes resulting in either no performance change or improvement. However, certain plan changes may cause performance regressions. The use of SQL plan baselines significantly minimizes potential performance regressions resulting from a database upgrade.
Ongoing system and data changes can impact plans for some SQL statements, potentially causing performance regressions. The use of SQL plan baselines helps to minimize performance regressions and stabilize SQL performance.
Deployment of new application modules means introducing new SQL statements into the system. The application software may use appropriate SQL execution plans developed under a standard test configuration for the new SQL statements. If the system production configuration differs significantly from the test configuration, SQL plan baselines can be evolved over time to produce better performance.
The package is owned by SYS
. The EXECUTE
package privilege is required to execute its procedures. Any user granted the ADMINISTER
SQL
MANAGEMENT
OBJECT
privilege is able to execute the DBMS_SPM
package.
The DBMS_SPM
package uses the constants shown in Table 148-1, "DBMS_SPM Constants". These constants are defined as standard input for the time_limit
parameter of the EVOLVE_SQL_PLAN_BASELINE Function.
Table 148-1 DBMS_SPM Constants
Constant | Type | Value | Description |
---|---|---|---|
|
|
|
Oracle determines the appropriate time spent by the EVOLVE_SQL_PLAN_BASELINE Function. |
|
|
|
There is no limit to the time spent by the EVOLVE_SQL_PLAN_BASELINE Function. |
The DBMS_SPM
package defines a TABLE
type.
This table list the package subprograms in alphabetical order.
Table 148-2 DBMS_SPM Package Subprograms
Subprogram | Description |
---|---|
Accepts a plan based on the recommendation of an evolve task |
|
Changes an attribute of a single plan or all plans associated with a SQL statement using the attribute name/value format |
|
Cancels a currently executing evolve task |
|
Sets configuration options for SQL management base, in parameter/value format |
|
Creates an advisor task and sets its parameters |
|
Creates a staging table that used for transporting SQL plan baselines from one system to another |
|
Drops an evolved task |
|
Drops a single plan, or all plans associated with a SQL statement |
|
Evolves SQL plan baselines associated with one or more SQL statements |
|
Executes a previously created evolve task |
|
Implements a plan based on the recommendation of an evolve task |
|
Interrupts a currently executing evolve task |
|
Loads one or more plans present in the cursor cache for a SQL statement |
|
Loads plans stored in a SQL tuning set (STS) into SQL plan baselines |
|
Migrates existing stored outlines to SQL plan baselines |
|
Packs (exports) SQL plan baselines from SQL management base into a staging table |
|
Resets an evolve task to its initial state |
|
Resumes a previously interrupted task |
|
Displays the results of an execution of an automatic evolve task. |
|
Displays the results of an evolved task |
|
Sets a parameter of an evolve task |
|
Unpacks (imports) SQL plan baselines from a staging table into SQL management base |
The procedure accepts a plan based on the recommendation of an evolve task.
DBMS_SPM.ACCEPT_SQL_PLAN_BASELINE ( task_name IN VARCHAR2, object_id IN NUMBER := NULL, task_owner IN VARCHAR2 := NULL, force IN BOOLEAN := FALSE);
Table 148-3 ACCEPT_SQL_PLAN_BASELINE Procedure Parameters
Parameter | Description |
---|---|
|
Identifier of task to implement |
|
Identifier of the advisor framework object that represents a single plan. If |
|
Owner of the evolve task. Defaults to the current schema owner. |
|
Accept the plan even if the advisor did not recommend such an action. The default is |
This function changes an attribute of a single plan or all plans associated with a SQL statement using the attribute name/value format.
DBMS_SPM.ALTER_SQL_PLAN_BASELINE ( sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL, attribute_name IN VARCHAR2, attribute_value IN VARCHAR2) RETURN PLS_INTEGER;
Table 148-4 ALTER_SQL_PLAN_BASELINE Function Parameters
Parameter | Description |
---|---|
|
SQL statement handle. It identifies plans associated with a SQL statement for an attribute change. If |
|
Plan name. It identifies a specific plan. Default |
|
Name of plan attribute to set (see table below). |
|
Value of plan attribute to use (see table below) |
Table 148-5 Names & Values for ALTER_SQL_PLAN_BASELINE Function Parameters
Name | Description | Possible Values |
---|---|---|
|
' |
' |
|
' |
' |
|
' |
' |
|
Name of the plan |
String of up to 30 characters |
|
Plan description. |
String of up to 500 bytes |
When a single plan is specified, one of various statuses, or plan name, or description can be altered. When all plans for a SQL statement are specified, one of various statuses, or description can be altered. This function can be called numerous times, each time setting a different plan attribute of same plan(s) or different plan(s).
The procedure cancels a currently executing evolve task. All intermediate results are removed from the task.
This procedure sets configuration options for SQL management base, in parameter/value format. This function can be called numerous times, each time setting a different configuration option.
Table 148-7 CONFIGURE Procedure Parameters
Parameter | Description |
---|---|
|
Name of parameter to set (see table below) |
|
Value of parameter to use (see table below) |
Table 148-8 Names & Values for CONFIGURE Procedure Parameters
Name | Description | Possible Values | Default Value |
---|---|---|---|
|
Maximum percent of |
1,2, …, 50 |
10 |
|
Number of weeks to retain unused plans before they are purged |
5,6, …, 523 |
53 |
The default space budget for SQL management base is no more than ten percent of the size of SYSAUX
tablespace. The space budget can be set to a maximum of 50%. The default unused plan retention period is one year and one week, which means a plan will be automatically purged if it has not been used for more than a year. The retention period can be set to a maximum of 523 weeks (i.e. a little over 10 years).
When the space occupied by SQL management base exceeds the defined space budget limit, a weekly database alert is generated.
The function has two overloads, both of which create an advisor task and sets its parameters. This version which takes a SQL handle creates an evolve task in order to evolve one or more plans for a given SQL statement.
DBMS_SPM.CREATE_EVOLVE_TASK ( sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL, time_limit IN NUMBER := DBMS_SPM.AUTO_LIMIT, task_name IN VARCHAR2 := NULL, description IN VARCHAR2 := NULL) RETURN VARCHAR2; DBMS_SPM.CREATE_EVOLVE_TASK ( plan_list IN DBMS_SPM.NAME_LIST, time_limit IN NUMBER := DBMS_SPM.AUTO_LIMIT, task_name IN VARCHAR2 := NULL, description IN VARCHAR2 := NULL) RETURN VARCHAR2;
Table 148-9 CREATE_EVOLVE_TASK Function Parameters
Parameter | Description |
---|---|
|
Handle of a SQL statement. The default |
|
List of plan names. The plans may belong to different SQL statements. |
|
Plan identifier. The default |
|
Time limit in number of minutes. The time limit is global and it is used in the following manner. The time limit for first non-accepted plan is equal to the input value. The time limit for the second non-accepted plan is equal to (input value - time spent in first plan verification) and so on. The default |
|
Evolve task name |
|
Description of the task (maximum 256 characters) |
This procedure creates a staging table used for transporting SQL plan baselines from one system to another.
DBMS_SPM.CREATE_STGTAB_BASELINE ( table_name IN VARCHAR2, table_owner IN VARCHAR2 := NULL, tablespace_name IN VARCHAR2 := NULL);
Table 148-10 CREATE_STGTAB_BASELINE Procedure Parameters
Parameter | Description |
---|---|
|
Name of staging table to create for the purpose of packing and unpacking SQL plan baselines |
|
Name of owner of the staging table. Default |
|
Name of tablespace. Default NULL means create staging table in the default tablespace. |
The creation of staging table is the first step. To migrate SQL plan baselines from one system to another, the user/DBA has to perform a series of steps as follows:
Create a staging table in the source system
Select SQL plan baselines in the source system and pack them into the staging table
Export staging table into a flat file using Oracle EXP utility or Data Pump
Transfer flat file to the target system
Import staging table from the flat file using Oracle IMP utility or Data Pump
Select SQL plan baselines from the staging table and unpack them into the target system
This function drops a single plan, or all plans associated with a SQL statement.
DBMS_SPM.DROP_SQL_PLAN_BASELINE ( sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL) RETURN PLS_INTEGER;
Table 148-12 DROP_SQL_PLAN_BASELINE Function Parameters
Parameter | Description |
---|---|
|
SQL statement handle. It identifies plans associated with a SQL statement that are to be dropped. If |
|
Plan name. It identifies a specific plan. Default |
This function evolves SQL plan baselines associated with one or more SQL statements. A SQL plan baseline is evolved when one or more of its non-accepted plans is changed to an accepted plan or plans. If interrogated by the user (parameter verify
= 'YES
'), the execution performance of each non-accepted plan is compared against the performance of a plan chosen from the associated SQL plan baseline. If the non-accepted plan performance is found to be better than SQL plan baseline performance, the non-accepted plan is changed to an accepted plan provided such action is permitted by the user (parameter commit
= 'YES').
The second form of the function employs a plan list format.
DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE ( sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL, time_limit IN INTEGER := DBMS_SPM.AUTO_LIMIT, verify IN VARCHAR2 := 'YES', commit IN VARCHAR2 := 'YES') RETURN CLOB; DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE ( plan_list IN DBMS_SPM.NAME_LIST, time_limit IN INTEGER := DBMS_SPM.AUTO_LIMIT, verify IN VARCHAR2 := 'YES', commit IN VARCHAR2 := 'YES') RETURN CLOB;
Table 148-13 EVOLVE_SQL_PLAN_BASELINE Function Parameters
Parameter | Description |
---|---|
|
SQL statement identifier. Unless |
|
Plan identifier. Default |
|
A list of plan names. Each plan in the list can belong to same or different SQL statement. |
|
Time limit in number of minutes. This applies only if
|
|
Specifies whether to execute the plans and compare the performance before changing non-accepted plans into accepted plans. A performance verification involves executing a non-accepted plan and a plan chosen from corresponding SQL plan baseline and comparing their performance statistics. If non-accepted plan shows performance improvement, it is changed to an accepted plan.
|
|
Specifies whether to update the
|
A CLOB
containing a formatted text report showing non-accepted plans in sequence, each with a possible change of its ACCEPTED
status, and if verify = 'YES
' the result of their performance verification.
The function executes a previously created evolve task.
DBMS_SPM.EXECUTE_EVOLVE_TASK ( task_name IN VARCHAR2, execution_name IN VARCHAR2 := NULL, execution_desc IN VARCHAR2 := NULL); RETURN VARCHAR2;
Table 148-14 EXECUTE_EVOLVE_TASK Function Parameters
Parameter | Description |
---|---|
|
Evolve task name |
|
Name to qualify and identify an execution. If not specified, it is generated by the advisor and returned by the function. |
|
Description of the execution (maximum 256 characters) |
The function implements all the actions recommended by an evolve task.
DBMS_SPM.IMPLEMENT_EVOLVE_TASK ( task_name IN VARCHAR2, task_owner IN VARCHAR2 := NULL, execution_name IN VARCHAR2 := NULL, force IN BOOLEAN := FALSE) RETURN NUMBER;
Table 148-15 IMPLEMENT_EVOLVE_TASK Function Parameters
Parameter | Description |
---|---|
|
Identifier of task to report |
|
Owner of the evolve task. Defaults to the current schema owner. |
|
Name to qualify and identify an execution. If |
|
Accept all plans even if the advisor did not recommend such an action. The default is |
The procedure interrupts a currently executing evolve task. The task ends its operations as at a normal exit and the user can access the intermediate results. The task can be resumed later.
This function loads one or more plans present in the cursor cache for a SQL statement, or a set of SQL statements. It has four overloads: using SQL statement text, using SQL handle, using SQL ID, or using attribute_name
and attribute_value
pair.
DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE ( sql_id IN VARCHAR2, plan_hash_value IN NUMBER := NULL, sql_text IN CLOB, fixed IN VARCHAR2 := 'NO', enabled IN VARCHAR2 := 'YES') RETURN PLS_INTEGER; DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE ( sql_id IN VARCHAR2, plan_hash_value IN NUMBER := NULL, sql_handle IN VARCHAR2, fixed IN VARCHAR2 := 'NO', enabled IN VARCHAR2 := 'YES') RETURN PLS_INTEGER; DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE ( sql_id IN VARCHAR2, plan_hash_value IN NUMBER := NULL, fixed IN VARCHAR2 := 'NO', enabled IN VARCHAR2 := 'YES') RETURN PLS_INTEGER; DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE ( attribute_name IN VARCHAR2, attribute_value IN VARCHAR2, fixed IN VARCHAR2 := 'NO', enabled IN VARCHAR2 := 'YES') RETURN PLS_INTEGER;
Table 148-17 LOAD_PLANS_FROM_CURSOR_CACHE Function Parameters
Parameter | Description |
---|---|
|
SQL statement identifier. Identifies a SQL statement in the cursor cache. Note: In the third overload the text of identified SQL statement is extracted from cursor cache and is used to identify the SQL plan baseline into which the plan(s) are loaded. If the SQL plan baseline doesn't exist it is created. |
|
Plan identifier. Default |
|
SQL text to use in identifying the SQL plan baseline into which the plans are loaded. If the SQL plan baseline does not exist, it is created. The use of text is crucial when the user tunes a SQL statement by adding hints to its text and then wants to load the resulting plan(s) into the SQL plan baseline of the original SQL statement. |
|
SQL handle to use in identifying the SQL plan baseline into which the plans are loaded. The |
|
Default |
|
One of possible attribute names:
|
|
Attribute value is used as a search pattern of |
|
Default ' |
This function loads plans stored in a SQL tuning set (STS) into SQL plan baselines. The plans loaded from STS are not verified for performance but added as accepted plans to existing or new SQL plan baselines. This function can be used to seed SQL management base with new SQL plan baselines.
DBMS_SPM.LOAD_PLANS_FROM_SQLSET ( sqlset_name IN VARCHAR2, sqlset_owner IN VARCHAR2 := NULL, basic_filter IN VARCHAR2 := NULL, fixed IN VARCHAR2 := 'NO', enabled IN VARCHAR2 := 'YES' commit_rows IN NUMBER := 1000) RETURN PLS_INTEGER;
Table 148-18 LOAD_PLANS_FROM_SQLSET Function Parameters
Parameter | Description |
---|---|
|
Name of the STS from where the plans are loaded into SQL plan baselines |
|
Owner of STS. |
|
A filter applied to the STS to select only qualifying plans to be loaded. The filter can take the form of any |
|
Default ' |
|
Default ' |
|
Number of SQL plans to load before doing a periodic commit. This helps to shorten the undo log. |
To load plans from a remote system, first load the plans into an STS on the remote system, export/import the STS from remote to local system, and then use this function.
To load plans from Automatic Workload Repository (AWR), first load the plans stored in AWR snapshots into an STS, and then use this procedure.
The user can also capture plans resident in the cursor cache for one or more SQL statements into an STS, and then use this procedure.
This function migrates stored outlines for one or more SQL statements to plan baselines in the SQL management base (SMB). Users can specify which stored outline(s) to be migrated based on outline name, SQL text, or outline category, or migrate all stored outlines in the system to SQL plan baselines.
This second overload of the function migrates stored outlines for one or more SQL statements to plan baselines in the SQL management base (SMB) given one or more outline names.
DBMS_SPM.MIGRATE_STORED_OUTLINE ( attribute_name IN VARCHAR2, attribute_value IN CLOB, fixed IN VARCHAR2 := 'NO') RETURN CLOB; DBMS_SPM.MIGRATE_STORED_OUTLINE ( outln_list IN DBMS_SPM.NAME_LIST, fixed IN VARCHAR2 := 'NO') RETURN CLOB;
Table 148-19 MIGRATE_STORED_OUTLINE Function Parameters
Parameter | Description |
---|---|
|
Specifies the type of parameter used in
|
|
Based on
|
|
|
|
List of outline names to be migrated |
A CLOB
containing a formatted report to describe the statistics during the migration, including:
Number of stored outlines successfully migrated
Number of stored outlines (and also the corresponding outline names) failed to be migrated and the reasons for the failure
When the user specifies an outline name, the function migrates stored outlines to plan baseline based on given outline name, which uniquely identifies a single stored outline to be migrated.
When the user specifies SQL text, the function migrates all stored outlines created for a given SQL statement. A single SQL statement can have multiple stored outlines created for it under different category names. One plan baseline plan is created for each stored outline. The new plan baselines have category names set to DEFAULT
. The module name of a plan baseline is set to be the same as the stored outline.
When the user specifies a category name, the function migrates all stored outlines with the given category name. Only one stored outline exists per category per SQL statement. One plan baseline is created for each stored outline.
When user specifies to migrate all
, the function migrates all stored outlines in the system to plan baselines. One plan baseline is created for each stored outline.
This function packs (exports) SQL plan baselines from SQL management base into a staging table.
DBMS_SPM.PACK_STGTAB_BASELINE ( table_name IN VARCHAR2, table_owner IN VARCHAR2 := NULL, sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL, sql_text IN CLOB := NULL, creator IN VARCHAR2 := NULL, origin IN VARCHAR2 := NULL, enabled IN VARCHAR2 := NULL, accepted IN VARCHAR2 := NULL, fixed IN VARCHAR2 := NULL, module IN VARCHAR2 := NULL, action IN VARCHAR2 := NULL) RETURN NUMBER;
Table 148-20 PACK_STGTAB_BASELINE Function Parameters
Parameter | Description |
---|---|
|
Name of staging table into which SQL plan baselines are packed (case insensitive unless double quoted) |
|
Name of staging table owner.Default |
|
SQL handle (case sensitive) |
|
Plan name (case sensitive, % wildcards accepted) |
|
SQL text string (case sensitive, % wildcards accepted) |
|
Creator of SQL plan baseline (case insensitive unless double quoted) |
|
Origin of SQL plan baseline, should be |
|
Must be ' |
|
Must be ' |
|
Must be ' |
|
Module (case sensitive) |
|
Action (case sensitive) |
The procedure resets an evolve task to its initial state. All intermediate results will be removed from the task. Call this procedure on a task that is not currently executing.
The procedure displays the results of an execution of an automatic evolve task.
DBMS_SPM.REPORT_AUTO_EVOLVE_TASK ( type IN VARCHAR2 := TYPE_TEXT, level IN VARCHAR2 := LEVEL_TYPICAL, section IN VARCHAR2 := SECTION_ALL, object_id IN NUMBER := NULL, execution_name IN VARCHAR2 := NULL) RETURN CLOB;
Table 148-23 REPORT_AUTO_EVOLVE_TASK Function Parameters
Parameter | Description |
---|---|
|
Type of the report. Possible values are |
|
Format of the report. Possible values are |
|
Particular section in the report. Possible values are: |
|
Identifier of the advisor framework object that represents a single plan. If |
|
Name to qualify and identify an execution. If |
The procedure displays the results of an evolved task.
DBMS_SPM.REPORT_EVOLVE_TASK ( task_name IN VARCHAR2, type IN VARCHAR2 := TYPE_TEXT, level IN VARCHAR2 := LEVEL_TYPICAL, section IN VARCHAR2 := SECTION_ALL, object_id IN NUMBER := NULL, task_owner IN VARCHAR2 := NULL, execution_name IN VARCHAR2 := NULL) RETURN CLOB;
Table 148-24 REPORT_EVOLVE_TASK Function Parameters
Parameter | Description |
---|---|
|
Identifier of task to report |
|
Type of the report. Possible values are |
|
Format of the report. Possible values are |
|
Particular section in the report. Possible values are: |
|
Identifier of the advisor framework object that represents a single plan. If |
|
Owner of the evolve task. Defaults to the current schema owner. |
|
Name to qualify and identify an execution. If |
The procedure sets a parameter of an evolve task, either a NUMBER
or VARCHAR2
.
DBMS_SPM.SET_EVOLVE_TASK_PARAMETER ( task_name IN VARCHAR2, parameter IN VARCHAR2, value IN NUMBER); DBMS_SPM.SET_EVOLVE_TASK_PARAMETER ( task_name IN VARCHAR2 := NULL, parameter IN VARCHAR2, value IN VARCHAR2);
This function unpacks (imports) SQL plan baselines from a staging table into SQL management base.
DBMS_SPM.UNPACK_STGTAB_BASELINE ( table_name IN VARCHAR2, table_owner IN VARCHAR2 := NULL, sql_handle IN VARCHAR2 := NULL, plan_name IN VARCHAR2 := NULL, sql_text IN CLOB := NULL, creator IN VARCHAR2 := NULL, origin IN VARCHAR2 := NULL, enabled IN VARCHAR2 := NULL, accepted IN VARCHAR2 := NULL, fixed IN VARCHAR2 := NULL, module IN VARCHAR2 := NULL, action IN VARCHAR2 := NULL) RETURN NUMBER;
Table 148-26 UNPACK_STGTAB_BASELINE Function Parameters
Parameter | Description |
---|---|
|
Name of staging table from which SQL plan baselines are unpacked (case insensitive unless double quoted) |
|
Name of staging table owner.Default NULL means current schema is the table owner |
|
SQL handle (case sensitive) |
|
Plan name (case sensitive,% wildcards accepted) |
|
SQL text string (case sensitive, % wildcards accepted) |
|
Creator of SQL plan baseline (case insensitive unless double quoted) |
|
Origin of SQL plan baseline, should be |
|
Must be ' |
|
Must be ' |
|
Must be ' |
|
Module (case sensitive) |
|
Action (case sensitive) |