APPLIES TO:

Oracle Database - Enterprise Edition - Version 11.1.0.6 and later

Information in this document applies to any platform.

PURPOSE

Statspack/AWR cannot be executed on a standby due to its read-only nature. Therefore tuning the performance of the apply process involves manually collecting statistics. 

In 11gR1, using the new Active Data Guard option, users can now use statspack from the primary database to collect data from a standby database that is opened read-only and performing recovery.  The standby statspack is installed in a separate schema on the Primary database, STDBYPERF which is then propagated to the standby. This new user does not have DBA privileges and has no access to local V$ tables.

SCOPE

This document applies to 11gR1 and up.

DETAILS

1. Standby Statspack Usage

1.1 Statspack Installation 

The perfstat schema and statspack related objects must be present on the primary and standby prior to installing standby statspack. 

If the perfstat user does not exist in the primary site then you will need to create the perfstat schema using the following:

sqlplus / as sysdba

SQL> @?/rdbms/admin/spcreate.sql

 

The standby statspack installation script (sbcreate.sql) creates the standby statspack schema to hold the standby snapshots. The script asks for:

1. A password for stdbyperf user

2. Default tablespace

3. Temporary tablespace

The script creates the ‘stdbyperf’ user and assigns it the selected default and temporary table space. After the user has been created it calls sbaddins.sql to add the first standby instance to the configuration.

Example:

SQL> @?/rdbms/admin/sbcreate

Note: Due to  , ensure global_names is set to 'FALSE' on the Standby Database while you run this Script. See   for some more Details.

Ensure the Initialization Parameter 'open_cursors' is set to at least 100 on the Primary and Standby Database.

1.2 Add an Instance to Statspack Configuration

Log in to the primary as the 'stdbyperf' user and run the script sbaddins.sql to add a standby instance to the configuration. The script asks for:

1. The TNS alias of the standby database instance

2. The password of the perfstat user on the standby site

The script then creates a private database link to the perfstat schema on the standby site and a separate gathering package for each standby instance. Example:

SQL> connect stdbyperf/your_password 

SQL> @?/rdbms/admin/sbaddins

Input inst2_alias as the tns alias.

1.3 Collect Performance Data from a Standby Instance

The script sbaddins.sql creates a separate PL SQL package for each standby instance. Run the snap procedure of those packages to collect the performance data. The statspack_<instance_name>.snap procedure accesses the data dictionary and stats$ views on the standby database via database link connected to the original perfstat user und stores the data to stats$ tables on the primary instance. For example, while the standby is opened read only, login to the primary database and create the snap:

SQL> connect stdbyperf/your_password

SQL> exec statspack_<db_unique_name>_<instance_name>.snap

1.4 Generate Standby Statistics Report

The script sbreport.sql generates the standby statistics report. The script asks for: database id, instance number, high and low snapshots id to create the report. Example:

SQL>@?/rdbms/admin/sbreport

1.5 Purge a Set of Snapshots

The script sbpurge.sql purges a set of snapshots. The script asks for database id, instance number, low and high snapshots ids. The script purges all snapshots between the low and high snapshot ids for the given instance. Example:

SQL>@?/rdbms/admin/sbpurge

1.6 Delete an Instance from the Configuration

The script sbdelins.sql deletes an instance from the configuration, and deletes the associated PL SQL package. The scripts asks for instance name. The snapshots are not automatically purged when the instance is deleted. After deleting the instance, you are not able to generate reports for that instance. Example:

SQL> @?/rdbms/admin/sbdelins

1.7 Drop Statspack Schema

The script sbdrop.sql drops the stdbyperf user and tables. The script must be run when connected to SYS (or internal).

Note that if you consider to reinstall Statspack you may have to drop all public synonyms for STATSPACK and STAT$%%. Else you may get an Error when trying to run spcreate again.

Example:

SQL> connect / as sysdba

SQL> @?/rdbms/admin/sbdrop

2. New Statistics Collected

Two new sections are added to standby statspack report: (1) Recovery Progress Stats, and (2) Managed Standby Stats. An example is provided below.

Recovery Progress Stats DB/Inst: MADISON/madison1 End Snap: 2

-> End Snapshot Time: 20-Jun-07 13:59:29

-> ordered by Item, Recovery Start Time desc

Recovery Start Time Item Sofar Units Redo Timestamp

------------------- ----------------- -------------- ------- ------------------

08-Jun-07 11:58:15 Active Apply Rate 8,420 KB/sec

08-Jun-07 11:58:15 Active Time 4,291 Seconds

08-Jun-07 11:58:15 Apply Time per Lo 267 Seconds

08-Jun-07 11:58:15 Average Apply Rat 3 KB/sec

08-Jun-07 11:57:15 Average Apply Rat 955 KB/sec

08-Jun-07 11:58:15 Checkpoint Time p 0 Seconds

08-Jun-07 11:58:15 Elapsed Time 1,044,073 Seconds

08-Jun-07 11:57:15 Elapsed Time 6 Seconds

08-Jun-07 11:58:15 Last Applied Redo 15,273,580 SCN+Tim 20-Jun-07 13:59:29

08-Jun-07 11:57:15 Last Applied Redo 13,945,701 SCN+Tim 08-Jun-07 11:56:16

08-Jun-07 11:58:15 Log Files 16 Files

08-Jun-07 11:57:15 Log Files 33 Files

08-Jun-07 11:58:15 Redo Applied 3,181 Megabyt

08-Jun-07 11:57:15 Redo Applied 6 Megabyt

-------------------------------------------------------------

Managed Standby Stats DB/Inst: MADISON/madison1 End Snap: 2

-> End Snapshot Time: 20-Jun-07 13:59:29

-> ordered by Process

Process pid Status Resetlog Id Thread Seq Block Num

----------- ---------- ------------ ----------- ------ ------- -----------

Client Proc Client pid Blocks Delay(mins)

----------- ---------- -------------- --------------

ARCH 29360 CLOSING 624693241 2 59 18433

ARCH 29360 340 0

ARCH 29358 CLOSING 624693241 1 57 94209

ARCH 29358 1,596 0

ARCH 29356 CLOSING 624693241 1 56 903169

ARCH 29356 1,835 0

ARCH 29354 CLOSING 624693241 2 61 919553

ARCH 29354 770 0

MRP0 30839 APPLYING_LOG 624693241 2 62 57

N/A N/A 2,097,152 0

RFS 28886 IDLE 0 0 0 0

N/A 16388 0 0

RFS 28875 IDLE 624693241 2 62 2164

LGWR 16137 432 0

RFS 30192 IDLE 624693241 1 58 51

LGWR 2092 1 0

RFS 28892 IDLE 0 0 0 0

UNKNOWN 16384 0 0

RFS 30326 IDLE 0 0 0 0

N/A 2268 0 0

-------------------------------------------------------------

3. List of New Scripts and Short Descriptions

All those Scripts below are located in $ORACLE_HOME/rdbms/admin

sbcreate.sql - Install standby statspack

sbcusr.sql - Called from sbcreate.sql to create the schema

sbctab.sql - Called from sbcreate.sql to create tables holding snapshots

sbaddins.sql - Called from sbcreate.sql to add a standby database instance to the configuration.

sbaddins.sql - Add a standby database instance to the configuration

sbcpkg.sql - Called from sbaddins.sql to create the instance specific statspack package

sblisins.sql - List instances in the standby statspack configuration

sbreport.sql - Create a standby statistics report

sbrepcon.sql - Called from sbreport.sql to get the report configuration

sbrepins.sql - Called from sbreport.sql to create the actual report

sbpurge.sql - Purge a set of snapshots identified by low and high snapshot ids

sbdelins.sql - Delete an instance from the standby statspack configuration

sbdrop.sql - Drop the stdbyoperf user and tables of the standby statspack

sbdtab.sql - Called from sbdrop.sql to drop tables

sbdusr.sql - Called from sbdrop.sql to drop user, must run from an account that connects to internal (SYS)

PLEASE NOTE

It is possible during the creation of the standby statspack package through the execution of spcreate.sql that it fails reporting the following error:

    ORA-00972: identifier is too long

This has resulted from the length of package names being limited to 30 characters.

To overcome this you would need to edit the script $ORACLE_HOME/rdbms/admin/sbaddins.sql and change the following line

FROM:

insert into stats$standby_config

values ('&&db_unique_name'

      , '&&inst_name'

      , 'STDBY_LINK_'||'&&tns_alias'

      , 'STATSPACK_'||'&&db_unique_name'||'_'||'&&inst_name');

TO:

insert into stats$standby_config

values ('&&db_unique_name'

      , '&&inst_name'

      , 'STDBY_LINK_'||'&&tns_alias'

      , 'SP_'||'&&db_unique_name'||'_'||'&&inst_name');

Invoking the package to collect snapshots would then mean you need to execute

SP_<db_unique_name>_<instance_name>.snap 

NOTE: if you are not sure how to do this contact support and this ONLY needs to be altered if the number of characters in STATSPACK_<db_unique_name>_<instance_name> exceeds 30.