Wayne SlomianyJanuary 29, 2008

Application Performance for DB2

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Agenda

• Targeted DB2 Data for Testing

• Efficient Coding Practices

• Efficient Application Relationships

• Using DB2 Stored Procedures

• Resolving DB2 Abends

• External Influences

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Targeted DB2 Data for Testing

Testing Audit Reports

z/OS

Distributed

z/OS

Distributed

Subset Extract

Load Maintain

Integrity

Apply Privacy Rules

Privacy Audit Reports

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Less Data, Less Resources

• Large TABLE loads can cause excessive resource usage and long LOAD times.

• Optimization of data used will decrease this.

• Usage of tools that support SORTKEYS in the load process which bypasses INDEX Key validation on each KEY written.

• Specifying LOG NO will prevent logging.

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Relationships of Data Intact

• Referential Integrity

• Application Relationships

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Production

Data Relationships

Distributed

Subset

Extract

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AR/RI

z/OS Relationships

Production

z/OS

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Efficient Coding Practices

“The later performance problems are caught in the life cycle, the

more costly they are to fix. Inefficiencies introduced in

design can cost twice as much to fix during programming,

four times more during system testing, and eight times more

when the application enters production.”

Accenture

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Pro-Active Application Relationship Management

• Normalize Database Including Application Relationships during Logical Design Phase

− Those used in Programs

− Those used in Driving Files

• Perform Physical Design (Table and Index) de-Normalizing for Performance

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Pro-Active Application Relationship Management

• Table joins tend to cause de-Normalization to improve performance.

• Focus on proper creation of INDEXs.

• Make Only Acceptable Relationships Available to Applications.

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Create a Baseline of the Application

• Identify what is acceptable (SLAs) for a particular application.

− End User response times.

− Overall system performance.

− Overall resource usage.

• Use this to compare future releases and Production.− Identify problem areas.

− Identify any changes made.

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Benefits of DB2 Stored Procedures

•Reduce Network traffic•Improve Security•Called from many programs/platforms•Easier to maintain data & logic

Data Servers

CICS/ IMSBatch

Browser Middleware

S390Servers

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DB2 Stored Procedures

• They reduce the SQL statements needed in the calling program.

• SQL is executed by the stored procedure and results are returned to the calling program.

• They have separate authority from the caller, allowing them to access and update tables that the caller can’t.

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DB2 Stored Procedures

• The caller only needs authorization to execute the stored procedure.

• This provides an additional level of security by preventing corruption of the SQL.

• This also eliminates outdated Client processes, the current stored procedure is always executed.

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DB2 Stored Procedures

• They must run using Language Environment.

• If a stored procedure does abend, there is only the LE dump to work with.

• The programmer could add his own trace code to try to narrow down the cause of the abend.

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DB2 Stored Procedures Challenges

Testing

Debugging

ProductionSupport

AnalysisAdded Complexity

Programmer Familiarity

Project Deadlines

Prevent Problems

Customer Satisfaction

Realize Benefits

- PLUS -

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-------------------- XPEDITER/TSO - Process DB2 Store Procedures --------------COMMAND ===>

Primary Commands: SEtup (display setup menu)

Stored Procedure Name ===> DOE.SPTEST1 Load Module name ===> PGM12345 (optional) Client End User Name ===> JOHNDOE DB2 AuthID ===> (DB2 Version 5 only) Luname ===> (DB2 Version 5 only) DB2 Sub System Name ===> DB61TEST Maximum number of Tests ===> (1 - 9999)

Specify Execute Jcl ===> N (Y or N)

Jobcard Information: ===> //PFHRAS0 JOB (#ACCONT),CLASS=A,MSGCLASS=X, ===> // MSGLEVEL=(1,1)

Press ENTER to process or enter END command to terminate

XPEDITER for DB2 Stored Procedures

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----------------------- XPEDITER/TSO - SELECT JOB STEP ----- Row 1 to 1 of 1COMMAND ===> SCROLL ===> PAGE

Line Commands: Primary Commands: I - Interactive testing Edit - Display converted selected steps U - Unattended testing END - Exit without processing IC - Interactive Code Coverage RUN - Submit and connect UC - Unattended Code Coverage SEtup - Setup work datasets SUBmit - Convert selected steps and submit blank - Reset I/U/C STatus - Display status of submitted job(s)

Dataset: 'SYS1.PROCLIB(D61WLM2)'

PROGRAM INITSCR STEPNAME PROCNAME PROCSTEP EXEC PGM-------------------------- --------------------------------------------------__ PGM12345 ________ XPTS0 XPAE001 RUNPROG XPTSO******************************* Bottom of data ********************************

XPEDITER for DB2 Stored Procedures

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------------------------- XPEDITER/TSO - SOURCE ------------------------------COMMAND ===> SCROLL ===> CSR BEFORE BREAKPOINT ENCOUNTERED ** END **

------ --------------------------------------------------- Before PGM12345<>=====> B FUNCTION = 'COMMAND'; /* SET FUNCTION FOR IFI CALL */000265 IFCA.LNGTH = STORAGE(IFCA); /* BYTES USED IN MEMORY */000266 IFCA.EYE_CATCHER = 'IFCA'; /* EYE CATCHER */000267 IFCA.OWNER_ID = 'LOC2'; /* DB2 LOCATION 1=LOCAL, 2=REMOTE*/000268 FREE RETURN_AREA; /* FREE STORAGE AND THEN */000269 /* ALLOCATE STORAGE FOR THE */000270 ALLOCATE 1 RETURN_AREA, /* RETURN AREA */000271 2 LNGTH,000272 2 RTRN_BUFF CHAR(4096);000273000274 RTRN_BUFF = ' '; /* CLEAR THE RETURN BUFFER */000275 RETURN_AREA.LNGTH = 4096; /* LENGTH OF RETURN BUFFER */000276 TEXT_OR_COMMAND=BLANK; /* CLEAR THE DB2 COMMAND AREA*/000277 OUTPUT_AREA.UNUSED = '00000000'B; /* CLEAR THE UNUSED AREA */000278 OUTPUT_AREA.LNGTH = LENGTH(INPUTCMD)+4; /* GET REAL LENGTH OF */000279 OUTPUT_AREA.TEXT_OR_COMMAND = INPUTCMD; /* ACTUAL DB2 COMMAND */

XPEDITER for DB2 Stored Procedures

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Resolving DB2 Application Abends

• Abends, including DB2, can use a large portion of the processor.

• Resolving them in a quick and complete fashion is important.

• Correlation of Application and DB2 information is important in resolution.

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CICS Application Abend

• Locate the task interface element (TIE) for “DSNCSQL”.

• Locate the CICS Life of Task (CLOT) in the TIE for DSNCSQL. Locate the SQL-PLIST using the pointer (CLOTPARM) from the CLOT.

• Validate the SQL-PLIST by locating the DBRM name once the SQL-PLIST is verified, the statement number, type, APARM (INPUT Host Variables) address, VPARM (OUTPUT Host variables) address, timestamp and pointer to the SQLCA have been located.

• To locate the SQLCODE, use the SQLCA pointer from the SQL-PLIST.

• Once located, the SQLCODE must be converted from HEX to DECIMAL before it can be used. For example, A -302 displays as “FFFFFED2” in the SQLCA.

• Look up the SQLCODE in the DB2 message and codes manual. The message text does not offer much more than an explanation.

• There are seldom any suggestions as to the cause of the problem.

• The statement number is used to locate the SQL statement in the precompile listing.

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Using Correlation

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Application Management Solution

Reduce excessive resource consumption at the root cause through a proactive and systemic approach.

Application Resource Management provides empirical data to help you make educated decisions.

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External Influences

Web Servers

ApplicationServers

DatabaseServers

Performance Overview

Response Times

Top Server Traffic

WAN Utilization

Top App by Traffic

Database Utilization

Delivery Stats

Server Performance

J2EE and .NET Analyzer

End user monitoring

Service Dashboard

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Distributed MQ Application

Client N-Tier Server

Back endServerQuery

Answer

Request 1

Reply 1

Request 2

Request3

Request 4

Reply 2

Reply 3

Reply 4Pdaaggr.exe

Pdarep2

2. Became aware of problem in real time (without any user interaction). Also got background information: unexpected 2033.

3. Traced the MQ message flow and saw that the 2033 was due to sluggish response from the mainframe application.

4. Analyzed the performance of the mainframe application – and saw a significant issue with MQ system-level tracing during bursts of activity.

1. Web application was occasionally failing.

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MQ Performance Impact

• Excessive wait time can impact DB2 performance.

• Difficult to identify the culprit.

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Environment Tuning

• Evolving applications introduce more potential points of failure

• Environmental complexity contributes to resource growth

• Gradual MIPS consumption can go undetected

• Reactive, fire-fighting mindset

• Limited expertise and skills

• Mainframe costs (hardware and software) are driven by MIPS

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Dynamic SQL Queries

• Usually rarely used however has great impact.

• Can involve large table scans with long wait times at the user end.

• Minimize and control as best possible.

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DB2 Environment Considerations

• Manage BUFFER POOLS based on recommendations per Version of DB2.

• Proper BUFFER POOL sizes: a good indicator is ratio of GETPAGES to synchronous reads of no greater than 10:1.

• There is a difference between read-only and read/write tables (maybe a separate BUFFER POOL here).

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Current Application Performance Metrics