Types of dimensionsIn Essbase, there are two types of dimensions, the first and most common dimension type is the Standard dimension.. Standard dimension Standard dimensions are derived
Trang 1Types of dimensions
In Essbase, there are two types of dimensions, the first and most common dimension
type is the Standard dimension The other less common dimension type is called an
Attribute dimension Both are explained here.
Standard dimension
Standard dimensions are derived from the main business data components (or data categories we described earlier) and are then defined in a database cube Some of
the Standard dimensions in our example database are: TOTAL VEHICLES, MEASURES,
CALENDER PERIODS, TOTAL MODEL YEARS, CUSTOMERS, MARKET, and SCENARIO These dimensions can be tagged as Accounts, Time, and Country types Some dimensions are not associated with any type of special dimension types and are considered
general dimensions
Briefly, let's explore the different ways you can tag a Standard dimension and
their uses
The Account dimension type
When you tag a dimension as an Account type, you are telling Essbase that this
dimension will be used for your financial measures or metrics
Available to the Account dimension are several accounting specific tags such as
the Time Balance option that uses the Time dimension to calculate period specific
data or the Two Pass Calculation option which will calculate the data in two
passes when components of that data must be calculated first from the existing data
The Time dimension type
The Time dimension type is the dimension where you define the periods used to
calculate and report your data This would typically be the dimension where you
store calendar periods The Time dimension also supports several of the Accounts
dimension functions
The Country dimension type
A dimension tagged as a Country dimension allows you to analyze your data across
multiple countries, if you desire You can also set the currency for each country to get true and current financial data analysis for each local market defined in your database
Trang 2No dimension type or general dimension
Not all dimensions need to have a specific identifier tag You can always create
a general dimension that you can use for any variety of data descriptor purposes
Most of your dimensions will be general dimensions
The Currency Partition dimension type
This type of dimension is used for currency conversion in your database
The database would contain all financial data represented in a base currency
The Currency Partition dimension is used to allow local currencies from
other regions to be brought in from a separate Essbase database
The Currency Partition dimension is specifically designed for currency
conversion applications and is not always necessary to achieve your desired
results Careful preparatory investigation upfront is always recommended
Below is a sample screenshot showing an outline containing dimensions that
are tagged with the various available dimension types Once the dimensions are
properly set, you will see the dimension type listed in the database outline next
to the dimension name
The specific dimension tags are for convenience and enhanced functionality However, many of these options were not available in earlier versions of Essbase so you would
have needed to code your own functionality
Trang 3The Attribute dimension
There is a dimension type known as an Attribute dimension type The Attribute
dimension is not a full blown standard dimension and in fact must be associated
with a standard dimension The Attribute dimension allows you to analyze your
data with even finer granularity by adding data characteristics (for example, color)
to your Total Vehicle dimension
If it is not an Attribute dimension type then it is some form of Standard dimension
Dense and Sparse dimensions
As we described before, the data stored in an Essbase database is stored in a manner conceptually similar to that of a Rubik's Cube Because of this structure, the folks at Oracle have devised a method of defining your outline dimensions and their data
density to Essbase Therefore, your database can be more efficient in the way it loads, stores, calculates, and retrieves your data
The distinction between Dense and Sparse dimensions allows Essbase to efficiently
handle large amounts of data that is not evenly spread across the data blocks It
is this efficiency that allows Essbase to offer the slice and dice style of data access,
while still maintaining high performance for fast data processing and retrievals
Correctly set Dense and Sparse dimension attributes have a
dramatic effect on overall memory usage and system performance!
• In a Sparse dimension, the data does not exist for the better
part of the member combinations For example, all vehicles may not be sold in all of the countries
• A Dense dimension has a very high percentage of available
data cells filled with data
First of all, you will need to consider whether a database dimension is Dense
or Sparse in an Application|Database that has been created using the BSO All
dimensions in an ASO database are Sparse by default When you have an Essbase
database created using the BSO, Essbase allows you to describe your dimensions as
either Dense or Sparse with the following understanding Some data cubes, created
roughly by dimension, are not fully populated with data In fact, for the most part,
the typical Essbase multidimensional database's cube always has a relatively Sparse
Trang 4When you first start out, you can let Essbase automatically configure the Dense
and Sparse dimension settings in your database You do this using the EAS Outline
Properties tab Essbase will do this fairly well initially, based on the data already
existing in the database
Notice in the preceding screenshot that there is an Auto configure option on the
outline properties screen If set to true, this option will let Essbase automatically
set the Dense/Sparse settings of the dimensions in your database.
As time goes on and as both your knowledge of your system's data grows and your
experience with Essbase increases, you will find that you can usually do a better job
of configuring the Dense and Sparse settings yourself rather than let Essbase handle it You can, at any time, change the Dense and Sparse attribute of any dimension
You will do this using the EAS at the database properties screen
One of the best features of Essbase is the outline or database restructure Anytime
you make a change to the database outline, you are offered the choice of saving the
changes when you attempt to close the outline The restructure choices available are
Outline Only and Outline and Data.
Trang 5When you make changes to your database outline, the changes may also affect the
way the data itself is stored Changes such as moving a member or changing a Dense setting to a Sparse setting will always require you to perform an Outline and Data
restructure When the restructure is called for, Essbase will actually perform what
could be best compared to in the relational world as database reorganization All of the existing data is unloaded and then reloaded into a structure that is most efficient for the new database outline configuration and settings
When Essbase is performing an Outline Only database restructure, the database
page files are not touched as only the database outline file is reorganized and resaved
An Outline Only restructure is triggered by making simple changes to the database,
including adding or updating an alias table or adding or updating a member property When Essbase deems it necessary to restructure the entire database, it will completely rebuild the database's page and index files This type of database restructure is
sometimes referred to as a Dense restructure What triggers a Dense restructure is
actually moving around the members in the database outline, adding new members
to the outline, or changing the Dense and Sparse setting on a dimension.
Very Important
When performing a database restructure, Essbase actually rebuilds
new temporary database page files from the existing page files When
finished, Essbase will delete the old page files and rename the new ones
Prior to any database restructure always make sure you have extra
storage on your server If the database you are restructuring is 30GB and
you only have 20GB of space available Essbase will keep on going with
the restructure until the disc space runs out and crashes the server!
VEHICLES
M A R K E T S
CALENDAR PERIODS