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Hyperion Interview Questions

Hyperion Interview Questions

Q. What are the two storage options available in Essbase and what are the differences?

ASO (Aggregate Storage Option) – Used for

  1. If we have large number of dimensions (generally more than 10)
  2. Most of the dimensions are sparse
  3. We cannot write back in ASO. I heard recently that ASO will also have the write back capability.

BSO (Block Storage Option)-

  1. Dimensions are less and dense (recommended values for no of dim are between 4 and 8) .
  2. We can write back hence much suited for planning applications.
    Financial applications are generally dense structures and normal analytical cubes are sparse. Here we also need to understand what these dense and sparse members are. When the intersections or cells of two dimensions mostly contain a value it is dense. Say for example we have two dimensions period(Month or quarter) and region and we are calculation the sales amount. Generally maximum regions(countries, cities) will have some sales value for a particular month or quarter. Hence we can say that our period dimensions would be dense. But now instead of period, consider another dimension product. Now there are some products which are sold in only some particular regions hence for them there will be no values in other regions or will have very low percentage of data values hence the structure will become sparse.
    Now the question arises what is the use of calling them dense or sparse. What difference does it make. Do some research and try to find the answer.

Q. Can we build dimensions directly from data sources without using rule files.

No.


Q. When do we generally use build rules files?

To automate the process of creating dimensions with thousands of members.


Q. What are the three primary build methods for building dimensions?

1. Generation references
2. level references
3. Parent-Child references.


Q. In what case we can define generation 1 to a field in generation build method.

We cannot define that as Generation 1 is not valid.


Q. Suppose we have assigned Generation 2 and Generation 4 as of now and think of adding generation 3 later some time. Can we build the dimension.

No. If gen 2 and gen 4 exists, we must assign gen 3.


Q. Can we create more than 2 dimensions using only one build rule file.

Yes, we can do that but it is recommended to use separate rule file for each dimension.


Q. What is UDA( user defined attributes). How are they different than Aliases.

UDA represents the class of the members. Aliases are just another names of the members. both are different and has different usage.


Q. Can we query a member for its UDA in a calculation script.

Yes. You can query a member for its UDA in a calculation script.


Q. How does UDA’s impact database size?

Absolutely no impact as UDA’s does not require additional storage space.


Q. What is the difference between UDA’s and Attribute dimensions?

Attribute dimensions provides more flexibility than UDA’s. Attribute calculations dimensions which include five members with the default names sum, count, min, max and avg are automatically created for the attribute dimensions and are calculated dynamically.


Q. How does Attribute dimensions and UDA’s impact batch calculation performance?

  • UDA’s- No Impact as they do not perform any inherent calculations.
  • Attribute dim- No Impact as they perform only dynamic calculations.

Q. How can we display UDA’s in reports? How do they impact report report performance.

UDA’s values are never displayed in the reports and hence do not impact report performance.


Q. How does Attribute dim impact report performance?

They highly impact the report performance as the attributes are calculated dynamically when referenced in the report. For very large number of att dim displayed in the report, the performance could drastically reduce.


Q. While loading the data, you have applied both the selection criteria as well as rejection criteria to a same record. What will be the outcome.

The record will be rejected.


Q. How is data stored in the Essbase database?

Essbase is an file based database where the data is stored in PAG files of 2 GB each and grows sequentially.


Q. Can we have multiple databases in one single application?

Yes. But only one database per application is recommended.


Q. Can we have one ASO database and one BSO database in one single application. If yes, how and If No, why.

No. Because we define ASO or BSO option while creating the application and not database. Hence if the application is ASO, the databases it contains will be that type only.


 

Q. What is the role of provider services.

To communicate between Essbase and Microsoft office tools.


Q. What is an alternative to create meta outline, rule file and load data.

Integration services and in version 11, we have Essbase studio.


Q. Can we start and stop an application individually. How can this be used to increase performance.

Yes. We can manage our server resources by starting only the applications which receive heavy user traffic. When an application is started, all associated databases are brought to the memory.


Q. We have created an application as unicode mode. Can we change it later to non-unicode mode.

No.


Q. How can I migrate an application from my test environment to the production environment. Can I still do this if my test environment is a windows one and my production env is UNIX one. Also can I still do it if my test env and prod env versions are different.

Hyperion Administrative services console provides a migration utility to do this but only the application, database objects are migrated and no data is transferred. the answers to other two questions are Yes.


Q. A customer wants to run two instances of an Essbase server on a same machine to have both test env and Development env on the same server. Can he do that?

Yes. We can have multiple instances of an Essbase server on a single machine and there will be different sets of windows services for all these instances.


Q. suppose I have a dimension A with members B and C and I do not want B and C to roll up to A. how can I do this.

Using (~) exclude from consolidation operator.


Q. What does never consolidate operator (^) do?

It prevents members from being consolidate across any dimension.


Q. Can we have multiple meta outlines based on one OLAP model in Integration services?

Yes


Q. Can we have an meta outline based on two different OLAP models.

No.


Q. What is hybrid analysis?

Lower level members and associated data remains in relational database where as upper level members and associated data resides in Essbase database.


Q. Why top-down calculation less efficient than a bottom-up calculation? Being less efficient, why do we use them.

In the process it calculates more blocks than is necessary. Sometimes it is necessary to perform top-down calculation to get the correct calculation results.


Q. On what basis you will decide to invoke a serial or parellel calculation method.

If we have a single processor, we will use serial calculation but if we have multiple processors we can break the task into threads and make them run on different processors.


Q. What is block locking system?

Analytic services (or Essbase Services) locks the block and all other blocks which contain the Childs of that block while calculating this block is block locking system.


 

Q. Dynamic calc decreases the retrieval time and increases batch database calculation time. How true is the statement?

The statement should be just opposite. As dynamic calc members are calculated when requested, the retrieval time should increase.

 


Q. Can we have multiple meta outlines based on one OLAP model in Integration services?

Yes


Q. What are LRO’s( Linked Reporting Objects)?

They are specific objects like files, cell notes or URL’s associated with specific data cells of Essbase database. You can link multiple objects to a single data cell. These linked objects are stored in the server. These LRO’s can be exported or imported with the database for backup and migration activities.


Q. How does UDA’s impact database size?

There will be no impact on the database as the UDA’s doesn’t store data in the database.


Q. Can we create UDA’s and apply it to Dense as well as Sparse dimensions?

Yes


Q. Types of Partitions available in Essbase?

Three types of partitions are there.

1. Transparent partition: A form of shared partition that provides the ability to access and manipulate remote data transparently as though it is part of your local database. The remote data is retrieved from the data source each time you request it. Any updates made to the data are written back to the data source and become immediately accessible to both local data target users and transparent data source users
2. Replicated Partition:
3. Linked Partition:

 


Q. Why top-down calculation less efficient than a bottom-up calculation? Being less efficient, why do we use them.

In the process it calculates more blocks than is necessary. Sometimes it is necessary to perform top-down calculation to get the correct calculation results.


Q. On what basis you will decide to invoke a serial or parallel calculation method.

If we have a single processor, we will use serial calculation but if we have multiple processors we can break the task into threads and make them run on different processors.


Q. How can you display UDA’s in reports?

UDA’s values are never displayed in the reports and hence do not impact report performance.


 

Q. What are the specified roles other than Administrator to view sessions, disconnect sessions or kill users requests for a particular application?

You should have the role of Application manager for the specified application.


Q. What is block locking system?

Analytic services (or Essbase Services) locks the block and all other blocks which contain the Childs of that block while calculating this block is block locking system.


Q. What are the three options specified in Username and Password management under security tab in Essbase server properties.

1. Login attempts allowed before username is disabled.
2. Number of inactive days before username is disabled.
3. Number of days before user must change password.


Q. Can we have multiple databases in one single application?

Yes. But only one database per application is recommended.
Depend on which database that you are going to create. For Example: If you are creating ASO then we can’t create more that 1 db per application. If you are creating BSO then you can create more than 1 db per application


Q. How is data stored in the Essbase database?

Essbase is an file based database where the data is stored in PAG files of 2 GB each and grows sequentially.


Q. We have created an application as unicode mode. Can we change it later to non-unicode mode.

No


 

Q. Dynamic calc decreases the retrieval time and increases batch database calculation time. How true is the statement?

The statement should be just opposite. As dynamic calc members are calculated when requested, the retrieval time should increase.


Q. What is the role of provider services.

To communicate between Essbase and Microsoft office tools.


Q. A customer wants to run two instances of an Essbase server on a same machine to have both test environment and Development environment on the same server. Can he do that?

Yes. We can have multiple instances of an Essbase server on a single machine and there will be different sets of windows services for all these instances.


Q. Why top-down calculation less efficient than a bottom-up calculation? Being less efficient, why do we use them.

In the process it calculates more blocks than is necessary. Sometimes it is necessary to perform top-down calculation to get the correct calculation results.


Q. Can we have multiple databases in one single application?

Yes. But only one database per application is recommended.


Q. Can we have one ASO database and one BSO database in one single application. If yes, how and If No, why.

No. Because we define ASO or BSO option while creating the application and not database. Hence if the application is ASO, the databases it contains will be that type only.


Q. What are the file extensions for an outline, rule file and a calc script.

.OTL, .RUL and .CSC


Q. What is the role of provider services.

To communicate between Essbase and Microsoft office tools.


Q. What is an alternative to create meta outline, rule file and load data.

Integration services and in version 11, we have Essbase studio.


Q. What is data file cache?

A buffer in memory that holds compressed data (.PAG) files.


Q. What is custom defined function?

Essbase calculation functions that you develop in the Java programming language and then add to the standard Essbase calculation scripting language by means of MaxL.


Q. Can we start and stop an application individually. How can this be used to increase performance.

Yes. We can manage our server resources by starting only the applications which receive heavy user traffic. When an application is started, all associated databases are brought to the memory.


Q. We have created an application as Unicode mode. Can we change it later to non-unicode mode.

No.


Q. How can I migrate an application from my test environment to the production environment. Can I still do this if my test environment is a windows one and my production env is UNIX one. Also can I still do it if my test env and prod env versions are different.

Hyperion Administrative services console provides a migration utility to do this but only the application, database objects are migrated and no data is transferred. the answers to other two questions are Yes.


Q. A customer wants to run two instances of an Essbase server on a same machine to have both test env and Development env on the same server. Can he do that?

Yes. We can have multiple instances of an Essbase server on a single machine and there will be different sets of windows services for all these instances.


Q. Suppose I have a dimension A with members B and C and I do not want B and C to roll up to A. how can I do this.

Using (~) exclude from consolidation operator.


Q. What is custom based macro?

Essbase macros that we write with Essbase calculator functions and special macro functions. Custom-defined macros use an internal essbase macro language that enables you to combine calculation function and operate on multiple input parameters.


Q. What do you mean by dirty block?

A data block containing cells that have been changed since the last calculation. Upper level blocks are marked as dirty if their child blocks are dirty (that is, have been updated)


Q. When do we generally use build rules files?

To automate the process of creating dimensions with more members, where it will take a lot of time in creating manually.


Q. What does never consolidate operator(^) do?

It prevents members from being consolidate across any dimension.


Q. What are the different types of LOG Files?

So many log files are there in essbase, but the important log files are

1. Application log
2. Essbase.log
3. Configtool.log
4. eas_install.log
5. essbaseserver-install.log


Q. Suppose we have assigned Generation 2 and Generation 4 as of now and think of adding generation 3 later some time. Can we build the dimension.

No. If gen 2 and gen 4 exists, we must assign gen 3.


Q. What are attributes?

A classification of a member in a dimension. You can select and group members based on their associated attributes. You can also specify an attribute when you perform calculations and use calculation functions. Eg: The database in Sample Basic which has product dimension has some attributes like size, package type, and flavor. We can add these attributes to the dimensions where we can retrieve the data like for example to retrieve “coke with 8 Oz with bottles”, this is useful for generating reports.


Q. Why do objects gets locked and when does this happens?

Objects gets locked to prevent users to make simultaneous and conflicting changes to Essbase database objects. By default whenever an object is accessed through Administrative services console or Excel spreadsheet add-in, it gets locked.


 

 

Q. What are different types of attributes?

Essbase supports two different types of attributes.

  • User-Defined attributes
  • Simple attributes

User-Defined attributes: The attributes that are defined by the user.
Simple attributes: Essbase supports some attributes, they are: Boolean, date, number, and string.


Q. What are filters?

A method of controlling access to database cells in essbase. A filter is the most detailed level of security, allowing you to define varying access levels different users can have to individual database values.


Q. What is TB First and TB Last?

TB First: in the Sample Basic database, the accounts member Opening Inventory is tagged as TB First. Opening Inventory consolidates the value of the first month in each quarter and uses that value for that month’s parent. For example, the value for Qtr1 is the same as the value for Jan.
TB Last: in the Sample Basic database, the accounts member Ending Inventory is tagged as TB Last. Ending Inventory consolidates the value for the last month in each quarter and uses that value for that month’s parent. For example, the value for Qtr1 is the same as the value for Mar.


Q. How can we display UDA’s in reports? How do they impact report report performance.

UDA’s values are never displayed in the reports and hence do not impact report performance.


Q. How does Attribute dim impact report performance?

They highly impact the report performance as the attributes are calculated dynamically when referenced in the report. For very large number of att dim displayed in the report, the performance could drastically reduce.


Q. How is data stored in the Essbase database?

Essbase is an file based database where the data is stored in PAG files of 2 GB each and grows sequentially.


Q. How do you optimize outline?

Usually the outline is optimized using the hourglass design for dimension ordering i.e,

  • Dimension with Accounts tag
  • Dimension with Time tag
  • Largest Dense dimension
  • Smallest dense dimension
  • Smallest Sparse dimension
  • Largest Sparse dimension

Q. What are the ways to improve performance during data loads?

There are several ways to optimize load

  1. Grouping of Sparse member combinations
  2. Making the data source as small as possible
  3. Making source fields as small as possible
  4. Positioning the data in the same order as the outline
  5. Loading from Essbase Server
  6. Managing parallel data load processing

Q. What are the design considerations for calculation optimization?

You can configure a database to optimize calculation performance. The best configuration for the site depends on the nature and size of the database.

  • Block Size(8Kb to 100Kb) and Block Density
  • Order of Sparse Dimensions
  • Incremental Data Loading
  • Database Outlines with Two or More Flat Dimensions
  • Formulas and Calculation Scripts

Q. When does Fragmentation occur?

Fragmentation is likely to occur with the following:

  • Read/write databases that users are constantly updating with data
  • Databases that execute calculations around the clock
  • Databases that frequently update and recalculate dense members
  • Data loads that are poorly designed
  • Databases that contain a significant number of Dynamic Calc and Store members
  • Databases that use an isolation level of uncommitted access with commit block set to zero

Q. How can you measure fragmentation?

You can measure fragmentation using the average clustering ratio or average fragmentation Quotient.

Using the average fragmentation quotient

Any quotient above the high end of the range indicates that reducing fragmentation may help performance

  • Small (up to 200 MB) 60% or higher
  • Medium (up to 2 GB) 40% or higher
  • Large (greater than 2 GB) 30% or higher

Using the average clustering ratio:

The average clustering ratio database statistic indicates the fragmentation level of the data (.pag) files. The maximum value, 1, indicates no fragmentation.


Q. How do you can prevent and remove fragmentation?

You can prevent and remove fragmentation:

  • To prevent fragmentation, optimize data loads by sorting load records based upon sparse dimension members. For a comprehensive discussion of optimizing data load by grouping sparse members.
  • To remove fragmentation, perform an export of the database, delete all data in the database with CLEARDATA, and reload the export file.
  • To remove fragmentation, force a dense restructure of the database.

Q. Why is database restructuring?

As your business changes, you change the Essbase database outline to capture new product lines, provide information on new scenarios, reflect new time periods, etc. Some changes to a database outline affect the data storage arrangement, forcing Essbase to restructure the database.


Q. What are the types of database restructuring?

The two ways by which a database restructure is triggered:

  • Implicit Restructures
  • Dense restructure
  • Sparse restructure
  • Outline-only restructure
  • Explicit Restructures

Q. What are the conditions affecting Database restructuring?

Intelligent Calculation, name changes, and formula changes affect database restructuring:

  • If you use Intelligent Calculation in the database, all restructured blocks are marked as dirty whenever data blocks are restructured. Marking the blocks as dirty forces the next default Intelligent Calculation to be a full calculation.
  • If you change a name or a formula, Essbase does not mark the affected blocks as dirty. Therefore, you must use a method other than full calculation to recalculate the member or the database.

Q. What are the files used during Restructuring?

When Essbase restructures both the data blocks and the index, it uses the files described

essxxxxx.pag

Essbase data fileessxxxxx.ind

Essbase index filedbname.esm

Essbase kernel file that contains control information used for db recoverydbname.tct

Transaction control tabledbname.ind

Free fragment file for data and index free fragmentsdbname.otl

Outline file in which is defined all metadata for a database and how data is stored


Q. What are the actions that improve performance for restructuring?

There are a number of things you can do to improve performance related to database restructuring:

  • If you change a dimension frequently, make it sparse. · Use incremental restructuring to control when Essbase performs a required database restructuring. · Select options when you save a modified outline that reduce the amount of restructuring required.

Q. What are LRO’s( Linked Reporting Objects)?

They are specific objects like files, cell notes or URL’s associated with specific data cells of Essbase database. You can link multiple objects to a single data cell. These linked objects are stored in the server. These LRO’s can be exported or imported with the database for backup and migtarion activities.


Q. What are the specified roles other than Administrator to view sessions, disconnect sessions or kill users requests for a particular application?

You should have the role of Application manager for the specified application.


Q. Why do objects gets locked and when does this happens?

Objects gets locked to prevent users to make simultaneous and conflicting changes to Essbase database objects. By default whenever an object is accessed through Administrative services console or Excel spreadsheet add-in, it gets locked.


Q. I have created an application with one database in Essbase at test environment and now needs to copy the entire application with all security permissions to the production server which is not connected to the test server. How can I do that?

You can achieve this using migration wizard to migrate an application to a text file which you can take physically to the production server.


Q. From the above question, When I migrated the application to the production server I do not see any data in the Essbase database. What has gone wrong and how to correct this?

Nothing has gone wrong. Migration utility does not migrate the actual data. If you want to copy the exact data from the test machine, get it exported using export utility and import it on production machine.


Q. Referring to the above question, Can I still do this if my production server and test server are two different operation systems. Explain.

While exporting the database, you can write the database data to an ASCII text file which enables you to load data on different platforms.


Q. How can we backup an aggregate storage database?

To back up an aggregate storage database, copy the application directory ARBORPATH/app/appname.


Q. How does Essbase recover from a database crash?

After a database crash or server interruption, Essbase automatically recovers a database after rolling back the transactions that were active at that time.


Q. How can you make a Max L script run at a specified time?

MaxL scripts can be called from a BAT file which is used for scheduling.

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