159 DBMS_WORKLOAD_CAPTURE

The DBMS_WORKLOAD_CAPTURE package configures the Workload Capture system and produce the workload capture data. Replay of this capture is implemented by way of the DBMS_WORKLOAD_REPLAY package.

Using DBMS_WORKLOAD_CAPTURE

Overview
Security Model

Overview

Since the capture infrastructure is instance wide (and also within an Oracle Real Application Clusters (Oracle RAC)), only one workload capture is being produced at any point in time. Thus capture interfaces do not need a state object passed in as a parameter since there is one single state at any point in time. This means that all subprograms cannot be methods of an object but are package wide PL/SQL subprograms.

Security Model

The following code describes the minimal set of privileges required to:

Create directory objects
Operate the interface provided by the DBMS_WORKLOAD_CAPTURE and DBMS_WORKLOAD_REPLAY packages
Act as a replay client user (wrc someuser/somepassword or wrc USER=someuser PASSWORD=somepassword)

DROP USER rom1 CASCADE;
CREATE USER rom1 IDENTIFIED BY rom1;
 
GRANT EXECUTE ON DBMS_WORKLOAD_CAPTURE TO rom1;
GRANT EXECUTE ON DBMS_WORKLOAD_REPLAY TO rom1;
 
GRANT CREATE SESSION TO rom1;
GRANT CREATE ANY DIRECTORY TO rom1;
GRANT SELECT_CATALOG_ROLE TO rom1;
GRANT BECOME USER TO rom1;

Appropriate OS permissions are required to access and manipulate files and directories on both the capture and replay system. This means that the Oracle process(es) and the OS user performing the capture or replay must be able to access and manipulate at least one common directory accessible from the host where the instance is running. Additionally, the OS user performing the replay should be able to execute wrc on hosts that are used for the replay clients and be able to access the file system appropriately to copy the capture to the replay clients' hosts if required.

Summary of DBMS_WORKLOAD_CAPTURE Subprograms

This table list the package subprograms in alphabetical order.

Table 159-1 DBMS_WORKLOAD_CAPTURE Package Subprograms

Subprogram	Description
ADD_FILTER Procedures	Adds a specified filter
DELETE_CAPTURE_INFO Procedure	Deletes the rows in the `DBA_WORKLOAD_CAPTURES` and `DBA_WORKLOAD_FILTERS` views that corresponds to the given workload capture ID
DELETE_FILTER Procedure	Deletes a specified filter
EXPORT_AWR Procedure	Exports the AWR snapshots associated with a given capture ID
FINISH_CAPTURE Procedure	Finalizes the workload capture by signaling all connected sessions to stop capture, and stops future requests to the database from being captured
GET_CAPTURE_INFO Function	Retrieves all the information regarding a workload capture present in the stipulated directory, imports the information into the `DBA_WORKLOAD_CAPTURES` and `DBA_WORKLOAD_FILTERS` views, and returns the appropriate `DBA_WORKLOAD_CAPTURES`.`ID`
IMPORT_AWR Function	Imports the AWR snapshots associated with a given capture ID
REPORT Function	Returns a report on the workload capture under consideration using one or more different sources
START_CAPTURE Procedure	Initiates workload capture on all instances

ADD_FILTER Procedures

This procedure adds a filter to capture a subset of the workload.

Syntax

DBMS_WORKLOAD_CAPTURE.ADD_FILTER (
   fname           IN   VARCHAR2 NOT NULL, 
   fattribute      IN   VARCHAR2 NOT NULL, 
   fvalue          IN   VARCHAR2 NOT NULL);

DBMS_WORKLOAD_CAPTURE.ADD_FILTER (
   fname           IN   VARCHAR2 NOT NULL, 
   fattribute      IN   VARCHAR2 NOT NULL, 
   fvalue          IN   NUMBER NOT NULL);

Parameters

Table 159-2 ADD_FILTER Procedure Parameters

Parameter Description

Parameter	Description
`fname`	Name for the filter to be added. Can be used to delete the filter later if it is not required. (Mandatory)
`fattribute`	Specifies the attribute on which the filter needs to be applied (Mandatory). The possible values are: `INSTANCE_NUMBER` - type `NUMBER` `USER` - type `STRING` `MODULE` - type `STRING` `ACTION` - type `STRING` `PROGRAM` - type `STRING` `SERVICE` - type `STRING`
`fvalue`	Specifies the value to which the given attribute should be equal to for the filter to be considered active. Wildcards like '%' are acceptable for all attributes that are of type `STRING`. This means that the filter for a `NUMBER` attribute is parsed as "attribute = value", with the filter for a `STRING` attribute parsed as "attribute like value" (Mandatory).

fname

Name for the filter to be added. Can be used to delete the filter later if it is not required. (Mandatory)

fattribute

Specifies the attribute on which the filter needs to be applied (Mandatory). The possible values are:

INSTANCE_NUMBER - type NUMBER
USER - type STRING
MODULE - type STRING
ACTION - type STRING
PROGRAM - type STRING
SERVICE - type STRING

fvalue

Specifies the value to which the given attribute should be equal to for the filter to be considered active. Wildcards like '%' are acceptable for all attributes that are of type STRING. This means that the filter for a NUMBER attribute is parsed as "attribute = value", with the filter for a STRING attribute parsed as "attribute like value" (Mandatory).

Usage Notes

The workload capture filters work in either the DEFAULT INCLUSION or the DEFAULT EXCLUSION mode as determined by the default_action input to the START_CAPTURE Procedure.
ADD_FILTER adds a new filter that affects the next workload capture, and whether the filters are considered as INCLUSION filters or EXCLUSION filters depends on the value of the default_action input to START_CAPTURE Procedure.
Filters once specified are valid only for the next workload capture. If the same set of filters need to be used for subsequent capture, they need to be specified each time before the START_CAPTURE Procedure is executed.
All the filters are listed in the DBA_WORKLOAD_FILTERS view.

DELETE_CAPTURE_INFO Procedure

This procedure deletes the rows in the DBA_WORKLOAD_CAPTURES and DBA_WORKLOAD_FILTERS views that corresponds to the given workload capture ID.

Syntax

DBMS_WORKLOAD_CAPTURE.DELETE_CAPTURE_INFO
   capture_id     IN   NUMBER);

Parameters

Table 159-3 DELETE_CAPTURE_INFO Procedure Parameters

Parameter	Description
`capture_id`	ID of the workload capture that needs to be deleted. Corresponds to `DBA_WORKLOAD_CAPTURES`.`ID`. (Mandatory)

Usage Notes

Passing the ID of a capture that is in progress will first automatically stop that capture.

DELETE_FILTER Procedure

This procedure deletes a specified filter.

Syntax

DBMS_WORKLOAD_CAPTURE.DELETE_FILTER (
   filter_name           IN   VARCHAR2(40) NOT NULL);

Parameters

Table 159-4 DELETE_FILTER Procedure Parameters

Parameter	Description
`filter_name`	Filter to be deleted

Usage Notes

The DELETE_FILTER Procedure only affects filters that have not been used by any previous capture. Consequently, filters can be deleted only if they have been added using the ADD_FILTER Procedures after any capture has been completed. Filters that have been added using ADD_FILTER before a START_CAPTURE and FINISH_CAPTURE cannot be deleted anymore using this subprogram.

EXPORT_AWR Procedure

This procedure exports the AWR snapshots associated with a given capture ID.

Syntax

DBMS_WORKLOAD_CAPTURE.EXPORT_AWR (
   capture_id     IN NUMBER);

Parameters

Table 159-5 EXPORT_AWR Procedure Parameters

Parameter	Description
`capture_id`	ID of the capture whose AWR snapshots are to be exported. (Mandatory)

Usage Notes

This procedure works only if the corresponding workload capture was performed in the current database (meaning that the corresponding row in DBA_WORKLOAD_CAPTURES was not created by calling the GET_CAPTURE_INFO Function) and the AWR snapshots that correspond to the original capture time period are still available.

FINISH_CAPTURE Procedure

This procedure signals all connected sessions to stop the workload capture and stops future requests to the database from being captured.

Syntax

DBMS_WORKLOAD_CAPTURE.FINISH_CAPTURE
   timneout     IN   NUMBER  DEFAULT 30
   reason       IN   VARCHAR2 DEFAULT NULL);

Parameters

Table 159-6 FINISH_CAPTURE Procedure Parameters

Parameter	Description
`timeout`	Specifies in seconds for how long the procedure should wait before it times out. Pass 0 if you want to cancel the current workload capture and not wait for any sessions to flush it's capture buffers. Default value: 30 seconds
`reason`	Specifies a reason for calling the procedure. The reason appears in the column `ERROR_MESSAGE` of the view `DBA_WORKLOAD_CAPTURES`.

Usage Notes

By default, FINISH_CAPTURE waits for 30 seconds to receive a successful acknowledgement from all sessions in the database cluster before timing out.
All sessions that either were in the middle of executing a user request or received a new user request, while FINISH_CAPTURE was waiting for acknowledgements, flush their buffers and send back their acknowledgement to FINISH_CAPTURE.
If a database session remains idle (waiting for the next user request) throughout the duration of FINISH_CAPTURE, the session might have unflushed capture buffers and does not send it's acknowledgement to FINISH_CAPTURE.

To avoid this, do not have sessions that remain idle (waiting for the next user request) while invoking FINISH_CAPTURE. Either close the database session(s) before running FINISH_CAPTURE or send new database requests to those sessions during FINISH_CAPTURE.

GET_CAPTURE_INFO Function

This procedure retrieves all information regarding a workload capture present in the stipulated directory, imports the information into the DBA_WORKLOAD_CAPTURES and DBA_WORKLOAD_FILTERS views, and returns the appropriate DBA_WORKLOAD_CAPTURES.ID

Syntax

DBMS_WORKLOAD_CAPTURE.GET_CAPTURE_INFO
   dir     IN   VARCHAR2)
  RETURN NUMBER;

Parameters

Table 159-7 GET_CAPTURE_INFO Function Parameters

Parameter	Description
`dir`	Name of the `DIRECTORY` object (case sensitive) where all the workload capture files are located (Mandatory)

Usage Notes

If an appropriate row describing the capture in the stipulated directory already exists in DBA_WORKLOAD_CAPTURES, the GET_CAPTURE_INFO Function simply returns that row's DBA_WORKLOAD_CAPTURES.ID. If no existing row matches the capture present in the stipulated directory a new row is inserted to DBA_WORKLOAD_CAPTURES and that row's ID is returned.

IMPORT_AWR Function

This procedure imports the AWR snapshots associated with a given capture ID provided those AWR snapshots were exported earlier from the original capture system using the EXPORT_AWR Procedure.

Syntax

DBMS_WORKLOAD_CAPTURE.IMPORT_AWR (
   capture_id       IN   NUMBER,
   staging_schema   IN   VARCHAR2,
   force_cleanup    IN   BOOLEAN DEFAULT FALSE)
 RETURN NUMBER;

Parameters

Table 159-8 IMPORT_AWR Function Parameters

Parameter Description

Parameter	Description
`capture_id`	ID of the capture whose AWR snapshots should be imported. (Mandatory)
`staging_schema`	Name of a valid schema in the current database which can be used as a staging area while importing the AWR snapshots from the capture directory to the `SYS` `AWR` schema.The `SYS` schema is not a valid input. (Mandatory, Case sensitive).
`force_cleanup`	Values: `TRUE` - any AWR data present in the given `staging_schema` are removed before the actual import operation. All tables with names that match any of the tables in AWR are dropped before the actual import. This typically is equivalent to dropping all tables returned by the following SQL: SELECT table_name FROM dba_tables WHERE owner = staging_schema AND table_name like 'WR_$%'; Use this option only if you are sure that there are no important data in any such tables in the `staging_schema`. `FALSE` - (default) no tables dropped from the `staging_schema` prior to the import operation

capture_id

ID of the capture whose AWR snapshots should be imported. (Mandatory)

staging_schema

Name of a valid schema in the current database which can be used as a staging area while importing the AWR snapshots from the capture directory to the SYS AWR schema.The SYS schema is not a valid input. (Mandatory, Case sensitive).

force_cleanup

Values:

TRUE - any AWR data present in the given staging_schema are removed before the actual import operation. All tables with names that match any of the tables in AWR are dropped before the actual import. This typically is equivalent to dropping all tables returned by the following SQL:
```
SELECT table_name FROM dba_tables
WHERE owner = staging_schema
AND table_name like 'WR_$%';
```
Use this option only if you are sure that there are no important data in any such tables in the staging_schema.
FALSE - (default) no tables dropped from the staging_schema prior to the import operation

Return Values

Returns the new randomly generated database ID that was used to import the AWR snapshots. The same value can be found in the AWR_DBID column in the DBA_WORKLOAD_CAPTURES view.

Usage Notes

IMPORT_AWR fails if the staging_schema provided as input contains any tables with the same name as any of the AWR tables, such as WRM$_SNAPSHOT or WRH$_PARAMETER. Please drop any such tables in the staging_schema before invoking IMPORT_AWR.

REPORT Function

This function generates a report on the stipulated workload capture.

Syntax

DBMS_WORKLOAD_CAPTURE.REPORT (
   capture_id      IN   NUMBER,
   format          IN   VARCHAR2)
 RETURN CLOB;

Parameters

Table 159-9 REPORT Function Parameters

Parameter Description

Parameter	Description
`capture_id`	ID of the workload capture whose capture report is required. (Mandatory) This relates to the directory that contains the workload capture on which the Report needs to be generated. Should be a valid `DIRECTORY` object that points to a valid directory in the host system that contains a workload capture.
`format`	Specifies the report format. Valid values are `DBMS_WORKLOAD_CAPTURE`.`TYPE_TEXT` and `DBMS_WORKLOAD_CAPTURE`.`TYPE_HTML`.(Mandatory)

capture_id

ID of the workload capture whose capture report is required. (Mandatory)

This relates to the directory that contains the workload capture on which the Report needs to be generated. Should be a valid DIRECTORY object that points to a valid directory in the host system that contains a workload capture.

format

Specifies the report format. Valid values are DBMS_WORKLOAD_CAPTURE.TYPE_TEXT and DBMS_WORKLOAD_CAPTURE.TYPE_HTML.(Mandatory)

Return Values

The report body in the desired format returned as a CLOB.

Table 159-10 Constants Used by Report Function

Constant	Type	Value	Description
`TYPE_HTML`	`VARCHAR2(4)`	'HTML'	Generates the HTML version of the report
`TYPE_TEXT`	`VARCHAR2(4)`	'TEXT'	Used as as input to the `format` argument to generate the text version of the report

START_CAPTURE Procedure

This procedure initiates workload capture on all instances.

Note:

The functionality associated with the capture_sts and sts_cap_interval parameters is available starting with Oracle Database 11g Release 2 (11.2.0.2).

Syntax

DBMS_WORKLOAD_CAPTURE.START_CAPTURE (
   name              IN  VARCHAR2,
   dir               IN  VARCHAR2,
   duration          IN  NUMBER   DEFAULT NULL,
   default_action    IN  VARCHAR2 DEFAULT 'INCLUDE',
   auto_unrestrict   IN  BOOLEAN  DEFAULT TRUE,
   capture_sts       IN  BOOLEAN  DEFAULT FALSE,
   sts_cap_interval  IN  NUMBER   DEFAULT 300);

Parameters

Table 159-11 START_CAPTURE Procedure Parameters

Parameter	Description
`name`	Name of the workload capture. Allows the workload capture to be given a label, such as "Thanksgiving weekend" or "Christmas peak workload" for future reference. The workload capture's name is preserved along with the captured workload actions. (Mandatory)
`dir`	Name of the `DIRECTORY` object (case sensitive) where all the workload capture files are stored. Should contain enough space to hold all the workload capture files. (Mandatory)
`duration`	Optional input to specify the duration (in seconds) for which the workload needs to be captured. `DEFAULT` is `NULL` which means that workload capture continues until the user executes `DBMS_WORKLOAD_CAPTURE`.`FINISH_CAPTURE`.
`default_action`	Can be either `INCLUDE` or `EXCLUDE`. Determines whether, by default, every user request should be captured or not. Also determines whether the workload filters specified should be considered as `INCLUSION` filters or `EXCLUSION` filters. If `INCLUDE`, by default all user requests to the database are captured, except for the part of the workload defined by the filters. In this case, all the filters specified using the ADD_FILTER Procedures are treated as `EXCLUSION` filters, determining the workload that is not captured. (`DEFAULT`, and so all the filters specified are assumed to be `EXCLUSION` filters.) If `EXCLUDE`, by default no user request to the database is captured, except for the part of the workload defined by the filters. In this case, all the filters specified using the ADD_FILTER Procedures are treated as `INCLUSION` filters, determining the workload that is captured.
`auto_unrestrict`	Can be either `TRUE` or `FALSE`. If `TRUE`, all instances started up in `RESTRICTED` mode using `STARTUP` `RESTRICT` are automatically unrestricted upon a successful `START_CAPTURE`. (`DEFAULT`) If `FALSE`, no database instance is automatically unrestricted.
`capture_sts`	If this parameter is `TRUE`, a SQL tuning set capture is also started in parallel with workload capture. The resulting SQL tuning set can be exported using the EXPORT_AWR Procedure along with the AWR data. Currently, parallel STS capture is not supported in an Oracle RAC environment, so this parameter has no effect if used in that context. Capture filters defined using the `DBMS_WORKLOAD_REPLAY` interface do not apply to the SQL tuning set capture. The calling user must have the appropriate privileges ('`ADMINISTER SQL TUNING SET`'). If starting SQL set capture fails, workload capture is stopped. The reason is stored in `DBA_WORKLOAD_CAPTURES`.`ERROR_MESSAGE`. The default value is `FALSE`.
`sts_cap_interval`	Specifies the capture interval of the SQL set capture from the cursor cache in seconds. The default value is 300.

Usage Notes

All user requests sent to database after a successful invocation of START_CAPTURE are recorded in the given dir directory for the given duration provided that one was specified. If no duration was specified, the capture lasts indefinitely until the FINISH_CAPTURE Procedure is executed.
A workload capture once started continues to record user requests across database instance shutdowns and startups for the specified duration, or until FINISH_CAPTURE is executed, whichever occurs first.
One can use workload filters (as described with regard to the ADD_FILTER Procedures) to capture only a subset of the user requests sent to the database. By default, when no workload filters are defined, all user requests are captured.
Workload that is initiated from Oracle Database background processes (such as SMON, PMON, MMON) and Oracle Database Scheduler Jobs (as detailed in the DBMS_SCHEDULER package) is not captured, no matter how the workload filters are defined. These activities should happen automatically on an appropriately configured replay system.
By default, all database instances that were started up in RESTRICTED mode using STARTUP RESTRICT are UNRESTRICTED upon a successful invocation of START_CAPTURE Use FALSE for the auto_unrestrict input parameter, if you do not want this behavior.
It is important to have a well-defined starting point for the workload so that the replay system can be restored to that point before initiating a replay of the captured workload. To have a well-defined starting point for the workload capture, it is preferable not to have any active user sessions when START_CAPTURE is executed. If ongoing sessions have ongoing transactions, those transactions are not replayed properly in subsequent database replays, since only that part of the transaction whose calls were executed after START_CAPTURE are replayed.