Cognos Best Practices

© 2008 IBM Corporation

®

IBM Software Group | WW GSI Alliance

Overview of Cognos 8 Best Practices Overview of Cognos 8 Best Practices

Rajib Bhattacharya | [email protected] | May 28, 200Rajib Bhattacharya | [email protected] | May 28, 20099

IBM Software Group | WW GSI Alliance | I’M the STAR

Agenda

� The purpose of this presentation is to provide best practices to users

who are already using IBM Cognos 8 or have basic understanding of

the features in IBM Cognos 8.

� This presentation includes few best practices regarding Installation,

Administration, Metadata Modeling, Reporting and basic Performance

Tuning.


Best Practices

� Installation Best Practices

� Administration Best Practices

� Metadata Modeling Best Practices

� Reporting Best Practices

� Performance Tuning Best Practices


Installation Best Practices – System Requirements

� Operating Systems – Windows, Solaris, HP-UX, AIX, Linux etc.

� Ram – Minimum 2 GB

� Disk Space - A minimum of 2.5 GB of free space is required to install

the software and 1 GB of free space on the drive that contains the

temporary directory used by IBM Cognos components.

� Web server - A Web server must be installed and started.

� JRE - JRE is installed automatically with IBM Cognos 8 on Windows. If

you are using an application server, use the JRE that is installed with it,

if it is supported in IBM Cognos 8.

� Database – Oracle, SQL server, DB2, Sybase etc.

� Refer to the Supported Environments and Supported Products pages

in IBM Cognos Support site.


Installation Best Practices - Terminology

� Different Components to be installed:

• Gateway - A gateway is an extension of a Web server program that transfers information from the Web server to another server.

• Application Tier Components - All application tier components include a dispatcher, that operates services and routes requests.

• Content Manager - Content Manager manages all IBM Cognos 8 information.

• Dispatcher - The dispatcher starts all IBM Cognos 8 services configured and enabled on a computer, and routes requests.

• Content Store - The content store is a relational database that contains data that IBM Cognos 8 needs to operate, such as reportspecifications, published models, and the packages that contain them; connection information for data sources; information about the external namespace, and the IBM Cognos namespace itself; and information about scheduling and bursting reports.

• For more details about these components refer to the document: Architecture and Deployment Guide


Installation Best Practices – Single Server Installation

� Use the installation wizard to select the server components that you

want to install and the location on your computer where you want to

install them.

� Windows Installations - For Windows installations, ensure that you have

administrator privileges for the Windows computer you are installing on.

Also ensure that your computer has a TEMP system variable that points

to the directory where you want to store temporary files. During

installation, files from the CD are temporarily copied to this directory.

� UNIX Installations - For UNIX installations, you can install server

components using either a character-based interface or a graphical user

interface. To run graphical-mode installation, the console attached to

your UNIX computer must support a Java-based graphical user

interface. Cognos recommends umask 022 on the installation directory.


Installation Best Practices – Single Server Installation


Installation Best Practices – Multiple Server Installation

� In a distributed environment, the sequence in which you configure

computers is important. Configure and start the computer with the active

Content Manager first. Then configure and start the computer with the

standby Content Manager, followed by the Application Tier Component

computer. Configure the gateway computer last so that cryptographic

keys are shared.

� If you need to stop services, the sequence is important. Stop the

Application Tier Components first, followed by the standby Content

Manager, and then the active Content Manager.

� For more details about the IBM Cognos 8 Installation refer to the

document: Installation and Configuration Guide


Installation Best Practices – Multiple Server Installation (Gateways on different Computers)


Installation Best Practices – Multiple Server Installation (Application Tier Components and Content Managers on different Computers)


Installation Best Practices – Content Store Database

� If you want to use IBM Cognos Content Database (Apache Derby) as

your content store, you must select it in the installation wizard. If you

are installing components on several computers, you need to only

install one IBM Cognos Content Database.

� Use Apache Derby as Content Store only in case of POCs or test

setups. Apache Derby is not an enterprise level database and has

limited capabilities. For production environment an enterprise level

database e.g., Oracle, SQL server etc. should be used as Content

store.

� While installing the product always use a blank database as Content

Store.

� For more details about the content store creation refer to the document:

Installation and Configuration Guide


Installation Best Practices - Samples

� Samples are on a separate CD in your IBM Cognos 8 product. If you want to

use the samples, you must install them from the IBM Cognos 8 Business

Intelligence Samples 8.4 CD.

� IBM Cognos Samples illustrate product features with technical and business

best practices.

� The samples consist of :

• Two databases that contain all corporate data, the related sample models for query and analysis, and sample cubes, reports, queries, query templates, and dashboards.

• Reports that contain extended tips to explain how and why they were created.

� If you are getting any problem with your model or reports, the first

troubleshooting step is to try and replicate the same problem against a sample

package.

� To find detailed steps to install samples please refer to the Samples chapter in

the document: Installation and Configuration Guide


Administration Best Practices – Security

� IBM Cognos 8 security is designed to meet the need for security in various situations. You can use it in everything from a POC where security is rarely enabled to a large scale enterprise deployment.

� To secure IBM Cognos 8, configure the product so that only users who belong to a specific group or role in your authentication source, or in the IBM Cognos namespace, are allowed access.

� IBM Cognos recommends using the IBM Cognos namespace because it contains preconfigured groups and roles that help you to secure IBM Cognos 8 quickly.

� Restricting User access in different IBM Cognos studios can be achivedby modifying the configuration settings under IBM Cognos Administration -> Security -> Capabilities

� For more details on Security refer to the document: Installation and Configuration Guide


Administration Best Practices – Keeping the Content Store small

� Keep as few versions of saved report outputs as possible. Saved

report outputs are stored in the content store therefore only keep the

lowest number of versions that still meets user requirements. This is

possible by modifying the Report output versions settings in a

report's properties.

� Delete any unused Exports from Content Administration. When you

perform a Content Store Export, certain entries are created in the

Content Store to facilitate faster future executions of this Export. You

should delete any Exports in Content Administration that aren't

scheduled or ran frequently.

� Run Content Maintenance Consistency Checks through Content

Administration to find and fix inconsistencies within the content store or

between the content store and external namespaces.


Administration Best Practices – Content Store Tuning and Backups

� The Content Store database needs to monitored and tuned like any

other production database. Regular backups of Content Store are

required, the frequency of backup depends on the importance of the data

being stored.

� Full content store backup is also possible using Content Administration

in IBM Cognos apart from default database backup methods.

Involvement of a DBA is required for monitoring, tuning and to take

backups of the Content Store database.

� We do not recommend using Content Store as the Audit Database. If the

Content Store is being used as Audit Database the performance will be

very slow as Cognos will perform write operations constantly to the audit

database.


Administration Best Practices – Scheduling Reports

� Scheduling reports in sequential manner is recommended rather than scheduling the reports concurrently.

� Schedule priorities can be set from 1 to 5. Setting a priority ensures that if two

reports are waiting in the queue to be run, the report with the higher priority is

run first. Overriding and resetting the priorities on any schedule is also possible.

� If you have administrator privileges, you can also schedule tasks that maintain

the content store, import or export entries from a deployment archive, run jobs

etc.

� If a report that contains prompts is scheduled, the prompt values must be

saved or default values must be specified to ensure that values exist when the report runs according to the schedule.

� For more details regarding scheduling reports refer the Schedule Management chapter in the document : Administration and Security Guide


Metadata Modeling Best Practices - Terminology

� Entity - Entities are the principal data objects about which information is to be collected; they usually denote a person, place, thing, or event of informational interest.

� Attributes - Attributes describe the characteristics of properties of the entities.

� Relationships - Relationships represent real-world associations among one or more entities, and, as such, have no physical or conceptual existence other than that which depends upon their entity associations.

� Cardinality - When relationships exist between two query subjects. The cardinality of a relationship is the number of related rows for each of the two query subjects.

� Fact - A fact is a collection of related data items, consisting of measures and context data.

� Dimension - A dimension is a collection of members or units of the same type of views.

� Measure - A measure is a numeric attribute of a fact, representing the performance or behavior of the business relative to the dimensions.


Metadata Modeling Best Practices – Relationships and Cardinality

� Verify relationships and cardinality - Cardinality affects how queries

are written and thus affects the results of a query. IBM Cognos 8 allows

cardinality to be specified by the modeler or generated based on criteria

in the database.

� Detect cardinality from data source - When importing from a

relational data source, cardinality is detected based on a set of rules

specified by the modeler. The available options are:

• Use primary and foreign keys

• Use matching query item names that represent uniquely indexed columns

• Use matching query item names

� General Rules applied to cardinality -

• 0-to-n or 1-to-n cardinality implies FACT

• 0-to-1 or 1-to-1 cardinality implies DIMENSION


Metadata Modeling Best Practices – Facts and Dimensions

� Identifying Facts - Within the context of a query, a query subject that has only maximum (n) cardinality on all its relationships to other query subjects can be regarded as a fact.

� Identifying Dimensions - Any query subject having at least one relationship to another query subject with minimum cardinality (1) will be treated as a dimension.

� Simplify the model with dimensional concepts –

• Use the cardinality rules from to identify areas of the model that ambiguously define dimensions or facts.

• Collapse groups of query subjects with hierarchical relationships into a single query subject per business concept (typically applies to dimensions).

• Collapse groups of query subjects with master/detail relationships into a single query subject per business concept (typically applies to facts).

• The end result of simplifying the model should be a layer of query subjects that clearly represent the data in terms of business concepts.


Metadata Modeling Best Practices – Ambiguous Relationships

� Cases of ambiguous relationships generally imply that the data

represented by a query subject can be viewed in more than one

context or role and should be modeled accordingly.

� Two common examples of ambiguous relationships are:

• Multiple Valid Relationships – Typically occur between dimensions and

facts. Create a shortcut or model query subject for each role with a single

relationship specific to the role.

• Recursive Relationships – Typically imply two or more levels of

granularity. As a minimum create a shortcut or model query subject each

for the parent and the child roles.


Metadata Modeling Best Practices – Define Dimensional information

� The primary purpose of dimensional information in Framework

Manager is to prevent double-counting.

� By specifying the internal cardinality or granularity of the data in a

query subject, it is possible to enhance the model and allow the query

engine to anticipate situations in which double-counting could occur.

� When specifying dimensional information the following needs to be

considered:

• Identification of the levels that are relevant for reporting purposes.

• Identification of the key(s) for those levels and if those keys uniquely

identify the members of their respective levels.

• Identify any attributes associated to levels.

• Identify the hierarchy of the levels – the relationship between levels.


Reporting Best Practices – Report Authoring Modes

� To meet the needs of both regular report authors and financial report authors, Report Studio provides distinct custom user interfaces that contain reporting features relevant to these roles.

� Professional Authoring Mode - This mode gives users access to the full range of Report Studio functionality. In this mode, you can create any report type, including charts, maps, lists, and repeaters, using any data source (relational or multi-dimensional). Professional authoring mode contains a superset of the features available in the Express authoring mode.

� Express Authoring Mode – This mode provides a simplified and focused Report Studio interface. It is designed for non-technical users to create traditional financial and management statement reports. Express authoring mode allows access only to dimensionally-modeled data. This authoring mode allows you to see live data and supports only crosstab reports. It contains a subset of the features available in the Professional authoring mode.


Reporting Best Practices – Creating Reports

� While designing any report there are two main aspects to consider:

• Queries - The data that drives your report.

• Formatting - The way the data is presented to the users.

� A common practice when designing a query is to try to do too much

with a single select statement. At times, the same results can be

retrieved by using multiple queries with less database overhead or

processing time and hence less execution time for the reports.

� It is recommended that the reports should be periodically tested while

authoring them in Report Studio to ensure that multiple error messages

are not encountered when the report is executed.

� In Express authoring mode, we do not recommend building calculations

or summaries on top of other calculations that were authored in the

Professional authoring mode.


Reporting Best Practices – Few more tips

� It is not recommended that you create a report in Analysis Studio then

open it in Report Studio and continue to design it.

� To move a single report from one Cognos environment to other, you can

copy the report specification from one environment and paste it in the

other environment. If the second environment is on a lower version, the

report might not work correctly, but if it is on a higher version report

specifications will be upgraded and the reports will work.

� If you are authoring a report with prompts which you would like to

schedule, you will either need to save the prompt values or specify

default values for the prompt, otherwise these reports will fail when

scheduled.


Reporting Best Practices - Troubleshooting

� Validating your reports – Report validation performs sanity checks on the report specifications and data types.

� Run similar reports against Cognos Samples – Create a similar report with the Cognos sample packages and execute the report and check if you get any errors.

� Checking the logs – The main log file is cogserver.log available in the directory : “<Cognos_Installation_Directory>/logs”

� Generating Report Specs – While working with technical support you might have to send the report spec to the support team. Report spec (or Report Specifications) are the XML formats of the reports. Either you can click on Show Specification button or copy the XML to clipboard by clicking the option Tools -> Copy Report to Clipboard and save the contents in notepad.


Performance Tuning Best Practices – Basic Performance Tuning

� Through IBM Cognos Connection, services can be modified to change

the performance behavior of the IBM Cognos 8 configuration. From the

IBM Cognos Administration page, navigate to the Server Administration

tab and make the changes as necessary.

� To find the details about all parameter to modify refer to IBM Cognos

Proven Practices document : Cognos 8 Performance Tuning Settings

available in IBM developerWorks


Performance Tuning Best Practices – Tuning Java Heap

� To improve performance sometimes editing the value for Java heap

size in Cognos configuration. For small configuration the default value is

768 MB, for medium configuration the default value is 1152 MB and for

a large configuration the default value is 1536 MB. To change this you

can edit the Maximum memory in MB parameter under IBM Cognos 8

Service. Otherwise you can also delete the service and add a new one

mentioning the specific configuration (small, medium or large) that you

are looking for. After making changes in Cognos configuration the

changes must be saved and service must be restarted.


Performance Tuning Best Practices – Sort Memory Tuning

� Sort Memory is the amount of memory that Cognos 8 uses to sort the

data which has been retrieved from the database. Editing Sort Memory

is required when you see that large reports are taking long time to

display results in Cognos Viewer even after the database has processed

the request. The Sort Buffer Size in MB (default value is 4 MB)

parameter under Environment in Cognos Configuration needs to be

modified. The value can be modified to 16 or 32 MB as required. We do

not recommend modifying this value more than 32 MB , because with

large values for Sort Memory there can be negative impacts and errors.

For the changes to effect you need to save the settings and restart the

service.


Important product documentation links

� IBM Cognos 8 Documentation

– IBM Cognos 8.4:

• http://publib.boulder.ibm.com/infocenter/c8bi/v8r4m0/index.jsp

– IBM Cognos 8.3:

• http://www-01.ibm.com/support/docview.wss?uid=swg27014543

– IBM Cognos 8.2:

• http://www-01.ibm.com/support/docview.wss?uid=swg27014542

� IBM Cognos Proven Practices

• http://www.ibm.com/developerworks/data/library/cognos/cognosprovenpractices.html

� Supportlink

• http://www-931.ibm.com/bin/newsletter/tool/parchive.cgi?nlId=11022

� Supported Environments

• http://www-01.ibm.com/support/docview.wss?rs=3528&uid=swg27014782

� Supported Products

• http://www-01.ibm.com/support/docview.wss?rs=3528&uid=swg27014713


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© Copyright IBM Corporation 2008 All rights reserved. The information contained in these materials is provided for informational purposes only, and is provided AS IS without warranty of any kind, express or implied. IBM shall not be responsible for any damages arising out of the use of, or otherwise related to, these materials. Nothing contained in these materials is intended to, nor shall have the effect of, creating any warranties or representations from IBM or its suppliers or licensors, or altering the terms and conditions of the applicable license agreement governing the use of IBM software. References in these materials to IBM products, programs, or services do not imply that they will be available in all countries in which IBM operates. Product release dates and/or capabilities referenced in these materials may change at any time at IBM’s sole discretion based on market opportunities or other factors, and are not intended to be a commitment to future product or feature availability in any way. IBM, the IBM logo, Cognos, the Cognos logo, and other IBM products and services are trademarks of the International Business Machines Corporation, in the United States, other countries or both. Other company, product, or service names may be trademarks or service marks of others.

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Cognos Best Practices