Database performance recommendations

BMC provides the following recommendations to optimize the performance of an Oracle database serving BMC Server Automation:

Recommendations for gathering statistics

As with other products which use an Oracle database, some performance problems in a BMC Server Automation environment can be caused by stale Oracle statistics on the BMC Server Automation schema, due to changing data volumes or changes in column values.

BMC strongly recommends that you gather statistics for the reports data warehouse and the core BMC Server Automation database and then clear the query caches after each data warehouse load.

To facilitate the running of the statistics gathering command, BMC Server Automation has a stored procedure. After the stored procedure is created in the BMC Server Automation schema, you can easily execute the procedure to gather statistics on a regular basis. BMC recommends that you gather statistics one time per week. Running the procedure more frequently than one time per week does not yield any additional performance improvement.

The statistics gathering procedure supplied by BMC Server Automation:

  • Collects Oracle optimizer statistics on the tables and indexes for the BMC Server Automation database at regular intervals.
  • Generates a PL/SQL script to collect statistics, which can be reviewed and modified (if necessary) before execution.

Warning

Although Oracle 10g and Oracle 11g provide an automatic job to gather statistics in the entire database, BMC strongly recommends that you exclude the BMC BladeLogic database schema from that job and instead use the statistics gathering package provided with BMC BladeLogic. Details about the package are described in the following sections.

Location of the BMC Server Automation statistics gathering package

The statistics gathering stored procedures are located in the ..\db_scripts\oracle\utility\gather_schema_stats folder, which is created when you extract external-files.zip. For information about this file, see Obtaining the installation files. The folder contains the following items:

  • bl_gather_schema_stats_sp.sql - Loads the BL_GATHER_SCHEMA_STATS stored procedure into the BMC Server Automation database; the procedure can either gather the statistics at the time of invocation, or send out PL/SQL commands for statistics gathering. The stored procedure is loaded automatically during the product installation or upgrade, so you do not have to manually load it.
  • gather_bl_schema_stats.sql - A sample script that illustrates how to invoke the stored procedure to collect statistics immediately.
  • generate_gather_schema_stats_script.sql - A sample script that illustrates how to invoke the stored procedure to generate a list of PL/SQL commands to gather statistics.
  • readme.txt - A detailed read-me file describing logic, usage, and so on.

Note

Before you run the script, ensure that you have met the following prerequisites:

  • Access to a fully operational computer with Oracle SQL*Plus installed that can connect remotely or locally to the BMC Server Automation database.
  • Oracle schema owner credentials for the BMC Server Automation database.
  • You can also run scripts and invoke the stored procedure as a user with DBA privileges. In this case, you must know the name of the schema owner for the BMC Server Automation database, and you must change the current schema before you run scripts or invoke the stored procedure using the ALTER SESSION SET CURRENT_SCHEMAcommand. For example:

    SQL> ALTER SESSION SET CURRENT_SCHEMA="BLADELOGIC";
    SQL> @gather_bl_schema_stats.sql
    

Gathering statistics at the time of invocation

To gather statistics immediately, perform any of the following:

  • Invoke the BL_GATHER_SCHEMA_STATS stored procedure directly from a PL/SQL block, or from any piece of code that is capable of calling Oracle stored procedures.
  • Run the sample script gather_bl_schema_stats.sqlin SQL*Plus. You can either execute the script as is, or edit the script to modify the stored procedure input parameters. The following is an example of script execution.

    SQL>@gather_bl_schema_stats.sql
    Finished collecting statistics. Time elapsed: +00 00:01:43.7780
    

    The following table describes the stored procedure input parameters.


    gather_bl_schema_stats.sql parameters

    Parameter

    Description

    p_threshold_rows

    Threshold based on the number of rows, the default is one million rows.

    p_threshold_bytes

    Threshold based on the table size, the default is one hundred mega bytes.

    p_no_invalidate

    Indicates whether to invalidate the child cursors currently cached in the SGA.

    p_print_only

    Instead of gathering statistics, send out PL/SQL commands for each table (this parameter requires serveroutput to be enabled on the client and set to unlimited size).

Generating a script to gather statistics at later time

Instead of gathering statistics when you invoke the stored procedure, you might want to generate a PL/SQL script that can be reviewed, edited and executed at later time.

The sample script generate_gather_schema_stats_script.sql provides an illustration of how to use a script to gather statistics at a later time. You can use the sample script as is or modify it to better suit your needs. The sample script creates a statistics collection script with an automatically generated name in the following format:
gather_schema_stats_autogen_YYYY_MM_DD_HH24_MI_SS.sql.

  1. To generate a new statistics collection script that you can execute at a later time, execute the generate_gather_schema_stats_script.sqlscript. The following example shows how to execute the script and illustrates the information that is returned upon execution.

    SQL> @generate_gather_schema_stats_script.sql
    Successfully generated stats collection script:
    gather_schema_stats_autogen_2010_02_19_17_44_32.sql
    
  2. Review the script to check the statistics collection settings for the various tables.
  3. Execute the script to gather statistics at a later time, such as during the maintenance window or during light system usage:
SQL> @gather_schema_stats_autogen_2010_02_19_17_44_32.sql
Started stats collection at 2010-02-19 17:44:43
Finished stats collection at 2010-02-19 17:46:05

Running gather statistics from the blcli

To run the gather statistics procedures from the BLCLI (for example, from a scheduled NSHScript Job), you can use the BLCLI command DBManager - blGatherSchemaStats command.

Verifying that statistics are current

You can run a database diagnostic to see if the DBMS_STATS on the Oracle schema are stale based on a parameter that you specify. If the previous run of DBMS_STATS is older than the time frame you specified, you are prompted to run the BL_GATHER_SCHEMA_STATS stored procedure to update the statistics. You can also instruct the diagnostic to perform autoremediation by automatically invoking the stored procedure.

The following example shows the command format you would use to run the DBMS_STATS_CHK diagnostic, while the the following table describes the parameters available for the diagnostic.

dbdiagnostics runDiag diagId=1000006 STATSExpiresDays=7
STATSRemediateFlg=Y


DBMS_STATS_CHK diagnostic parameters

Parameter

Description

STATSExpiresDays

Sets the time frame, in days, for the recommended frequency for updating statistics. The default value is 15 days.

STATSRemediateFlg

Controls autoremediation (execution of the of BL_GATHER_DBMS_STATS PROC script) to update the Schema statistics. Enter Y to turn on autoremediation; enter N to turn it off. The default value is N. Note: Remediation of the statistics could take a considerable amount of time, based on the size of the database on which the script is executed. Before executing the autoremediation of Schema STATS, consult with your DBA. If you use the Oracle STATS GATHER Package for database statistics, BMC recommends that you replace the automatic Oracle job for gathering statistics with the BMC Server Automation BL_GATHER_SCHEMA_STATS package.

 

To view the results of the diagnostic, run the dbdiagnostics command with the getResLastExec parameter, which displays the results of the last execution for this diagnostic.

dbdiagnostics getResLastExec diagId=10000006


For a description of all available database diagnostics, see Monitoring and diagnosing issues in the BMC Server Automation environment.

Recommendations for configuring the database

The following recommendations are for a 10-GB database. Scale the configuration recommendations up or down based on the relative size of your database.

Configuration parameter

Recommended value

db_cache_size

1 GB

log_buffer

512 KB

pga_aggregate_target

360 MB

undo tablespace size

2 GB

 

Recommendations for physical implementation

To avoid disk contention and increase input-output throughput when accessing data, store the physical data and index data files in different tablespaces (that is, across multiple disks).

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