IBM Cognos Interview Questions

A catalog is a file which contains information such as folders, columns, conditions, etc. on the database tables. The highlighted point here is that it doesn’t contain any data instead it contains metadata definitions and table structures. It has mainly four types:

• Personal Catalog: It is a type of catalog in which only one user can create or modify a catalog or report.
• Shared Catalog: In this, one user (creator) can create the catalog but other users can also create their own reports with the use of this catalog.
• Distributed Catalog: In this, anyone can change or modify their own created distributed catalogs and can also make their own reports.’
• Secured Catalog: In this type of catalog, no one can modify the reports or catalogs. They are fully secured.

It is used to find the hidden patterns and trends of data.

It has many advantages that are described below:

• It has the ability to design complex layouts with the use of different data sources.
• It shows faster results at lower costs.
• It can use a plethora of charts which includes cross tables, lines, gauges, bar charts and many more.
• It shows complete connectivity indifferent of an environment.
Cognos supports all RDBMS (Relational Database Management systems) to handle reporting data.
• It can perform on any operating system which means the user doesn't need to install again on changing the operating system.
• It creates reports very accurate, relevant and reliable.

Following are the ways to change non-durable models into durable model

• In the case of the model does not have a design language, then the steps are-
• It is the vital part of the method to attach the design language to the model. After that combine it to the languages of each package which is on the basis of the model. When it is done, save and close the model.
• Open the model.xml file with the help of using XML or text editor. After that modify the value to en-zw from en which is present near the top of the file.
• If you are using IBM Cognos 8.4.1 you need to add a blank line into the model.xml file which is located just under the modified element. When it is done, insert true to the new blank line.
• If you are using IBM Cognos 10 you need to fix the project level property. It is advised to make use of Design Locale for Reference ID to a value of true.

To be considered a durable model, it needs to follow some criteria and these are given below.

1. It is always a design language that is built up for the model which is different from the areas the clients can select from. As an example, English (Zimbabwe) is assigned for the language English.
2. The name of the languages of other than the design language can be changed if required but for design language, it is not possible to change namespaces, query items, query languages that are published in a package.
3. It is not possible to change the structure of the published package's query subject, query items, dimensions, namespace(s), shortcuts etc. The reason behind this is that the structure is kept in specification's definition with design language's name.
4. The element must be in model.xml in the version IBM Cognos 8.4.1.

Aggregate Advisor help in increasing the overall performance.

• It is a component of the Dynamic Query Analyzer
• It can be Support database either in-memory aggregate or aggregate tables or maybe both.
• Aggregate Advisor utilize statistics and cube’s model
• Aggregate Advisor utilize workload log files which are available from the execution of reports
• To recover the summed value and put the values in their specific aggregate cache so that they can be used for query processing, aggregate execute the important SQL statement after the cube restart.
• It works during the off-peak meanwhile in the non-critical business hours

It indicates the group of users who have the same rights and required to access the same data. It is the duty of the administrator to build the user class and catalog. This job of the creating and maintaining user class can also be performed by the other users of the organization in their geographical area.

You are also able to build a catalog and you can add the user to it. You can also add the users to the personal copy of a distributed catalog. You will get all the rights from the administrator so you can insert or make changes of user classes

• It is possible to analyze, monitor and report on information that is collected from different devices with the help of IBM Predictive Maintenance and Quality. Moreover, you can get the information regarding the actions from Predictive Maintenance and Quality.
• IBM Predictive Maintenance and Quality can employ to accomplish the following assignments:
• It is helpful in preventing costly unexpected break by earlier prediction of failure of any instrumented.
• It makes the changes in the maintenance to diminish break and help in reducing the cost of repair.
• It looks after the least costly and most powerful solution to the problem by maintaining the logs. It also helps in maintaining the cycles.
• It goes to the root of the cause of the problem vigorously so that clients can take suitable action to repair it.
• It determines the safety, security and quality issue to minimize the chances of failure.

It is a tool which is defined in Cognos to extract and transform the data from different data sources to target data sources.

There are many types of indexes used in Cognos. These are:

• Bitmap Indexes: A bitmap index is used to replace a list of rowids with the key values. Due to the presence of low cardinality and low updates, it is more efficient for data waring.
• B-tree indexes: B-tree indexes are used on the availability of high-cardinality, generally when we have too many distinct columns. It is mainly used for OLTP.
• Function-based indexes: These are created on the results of an expression or function.
• Reverse key and Composite Indexes: In the reverse key, the keys of an index are reversed and then stored.

It is the studio in which Cognos perform its Ad-hoc queries.

It is used to create advanced business reports.

Cognos Dynamic Cube encourages two types of pre-computed aggregate values and these are

1. Saved in in-database tables
2. Saved in an in-memory aggregate cache
• An aggregate advisor can hold a factory of in-memory aggregates and further in-memory aggregates do not need the DBA.
• Instructions are saved in the "Content Manager" and when a cube is started after this, it is affected.
• The properties of a dynamic cube decide the fate of the size of the aggregate cache that is the highest amount that can be used by the aggregate cache.

Two types:

Sequential: which runs the session one by one.

Concurrent: Which runs the sessions simultaneously

The different types of the report in Cognos are:

• Chart report
• List report
• Blank report
• Repeater report
• Cross report