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175 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.

See Also:

Oracle Database Testing Guide for more information about Database Replay

This chapter contains the following topics:


Using DBMS_WORKLOAD_CAPTURE


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 175-1 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 175-2 ADD_FILTER Procedure Parameters

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

  • PDB - 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.

  • You can capture the workload for a particular PDB by specifying a filter of PDB type.

Examples

  • By default, a capture works in an INCLUSION mode, which records everything except for those requests that satisfy conditions of specified filters. For example, if you want to exclude all requests from SCOTT, you can add the following filter before starting a capture.

    EXEC DBMS_WORKLOAD_CAPTURE.ADD_FILTER ('filter user1', 'USER', 'SCOTT');
    
  • Multiple filters are evaluated according to the logical disjunction operator OR. Therefore, if you want to record workload for both SCOTT and JOHN, you add an additional filter:

    EXEC DBMS_WORKLOAD_CAPTURE.ADD_FILTER ('filter user2', 'USER', 'JOHN');
    
  • In a CDB, you exclude the workload of a particular PDB by the filter:

    EXEC DBMS_WORKLOAD_CAPTURE.ADD_FILTER ('filter pdb workload', 'PDB_NAME', 'CDB1_PDB1');
    
  • To use DBMS_APPLICATION_INFO to identify workload that is issued to the database:

    DBMS_APPLICATION_INFO.SET_MODULE('ORDER_ENTRY', NULL);
    -- run some SQL here
    DBMS_APPLICATION_INFO.SET_ACTION('ORDER_ENTRY_LOG');
    -- run logging SQL
    
  • If having captured workload, you want to exclude the logging SQL from the captured, specify a filter for capture:

    DBMS_WORKLOAD_CAPTURE.ADD_FILTER('filter logging operations', 'ACTION', 'ORDER_ENTRY_LOG');
    
  • To filter out the full order entry transaction, define a filter:

    DBMS_WORKLOAD_CAPTURE.ADD_FILTER('filter order entry', 'MODULE', 'ORDER_ENTRY');
    

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 175-3 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 175-4 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 175-5 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
   timeout     IN   NUMBER  DEFAULT 30
   reason       IN   VARCHAR2 DEFAULT NULL);

Parameters

Table 175-6 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 175-7 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 175-8 IMPORT_AWR Function Parameters

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


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 175-9 REPORT Function Parameters

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)


Return Values

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

Table 175-10 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 input to the format argument to generate the text version of the report



START_CAPTURE Procedure

This procedure initiates workload capture on all instances.

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 175-11 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.