Skip to main content

Data Warehouse-Concepts

A fundamental concept of a data warehouse is the distinction between data and information.
Data is composed of observable and recordable facts that are often found in operational or transactional systems.At Rutgers, these systems include the registrar’s data on students (widely known as the SRDB), human
resource and payroll databases, course scheduling data, and data on financial aid.
In a data warehouse environment, data only comes to have value to end-users when it is organized and presented as information. Information is an integrated collection of facts and is used as the basis for decisionmaking.
For example, an academic unit needs to have diachronic information about its extent of
instructional output of its different faculty members to gauge if it is becoming more or less reliant on
part-time faculty.

The data warehouse is that portion of an overall Architected Data Environment that serves as the single
integrated source of data for processing information. The data warehouse has specific characteristics that
include the following:

Subject-Oriented: Information is presented according to specific subjects or areas of interest, not
simply as computer files. Data is manipulated to provide information about a particular subject. For
example, the SRDB is not simply made accessible to end-users, but is provided structure and organized
according to the specific needs.

Integrated: A single source of information for and about understanding multiple areas of interest. The
data warehouse provides one-stop shopping and contains information about a variety of subjects. Thus
the OIRAP data warehouse has information on students, faculty and staff, instructional workload, and
student outcomes.

Non-Volatile: Stable information that doesn’t change each time an operational process is executed.
Information is consistent regardless of when the warehouse is accessed.

Time-Variant: Containing a history of the subject, as well as current information. Historical
information is an important component of a data warehouse.

Accessible: The primary purpose of a data warehouse is to provide readily accessible information to
end-users.

Process-Oriented: It is important to view data warehousing as a process for delivery of information.
The maintenance of a data warehouse is ongoing and iterative in nature.

Data Warehouse: A data structure that is optimized for distribution. It collects and stores integrated
sets of historical data from multiple operational systems and feeds them to one or more data marts. It
may also provide end-user access to support enterprise views of data.

Data Mart: A data structure that is optimized for access. It is designed to facilitate end-user analysis of
data. It typically supports a single, analytic application used by a distinct set of workers.
 
Staging Area: Any data store that is designed primarily to receive data into a warehousing environment.

Operational Data Store: A collection of data that addresses operational needs of various operational
units. It is not a component of a data warehousing architecture, but a solution to operational needs.

OLAP (On-Line Analytical Processing): A method by which multidimensional analysis occurs.
Multidimensional Analysis: The ability to manipulate information by a variety of relevant categories
or “dimensions” to facilitate analysis and understanding of the underlying data. It is also sometimes
referred to as “drilling-down”, “drilling-across” and “slicing and dicing”

Hypercube: A means of visually representing multidimensional data.

Star Schema: A means of aggregating data based on a set of known dimensions. It stores data
multidimensionally in a two dimensional Relational Database Management System (RDBMS), such as
Oracle.

Snowflake Schema: An extension of the star schema by means of applying additional dimensions to the
dimensions of a star schema in a relational environment.

Multidimensional Database: Also known as MDDB or MDDBS. A class of proprietary, non-relational
database management tools that store and manage data in a multidimensional manner, as opposed to the
two dimensions associated with traditional relational database management systems.

OLAP Tools: A set of software products that attempt to facilitate multidimensional analysis. Can
incorporate data acquisition, data access, data manipulation, or any combination thereof.


Comments

Popular posts from this blog

ODI KM Adding Order by Option

You can add Order by statement to queries by editing KM.I have edited IKM SQL Control Append to provide Order by.  1) Add an option to KM named USE_ORDER_BY, its type is Checkbox and default value is False. This option determines you want an order by statement at your query. 2)Add second option to KM named ORDER_BY, type is Text. You will get order by values to your query by this option. 3) Editing Insert New Rows detail of KM. Adding below three line code after having clause. That's it! <% if (odiRef.getOption("USE_ORDER_ BY").equals("1")) { %> ORDER BY <%=odiRef.getOption("ORDER_BY" )%> <%} %>  If USE_ORDER_BY option is not used, empty value of ORDER_BY option get error. And executions of KM appears as such below; At this execution, I checked the KM to not get errors if ORDER_BY option value is null. There is no prove of ORDER BY I'm glad.  Second execution to get  Ord...

Creating Yellow Interface in ODI

Hello everyone! In Oracle data integrator (ODI), an  interface  is an object which populates one datastore, called the  target , with data coming from one or more other datastores, known as  sources . The fields of the source datastore are linked to those in the target datastore using the concept of  Mapping . Temporary interfaces used in ODI are popularly known as  Yellow Interfaces . It is because ODI generates a yellow icon at the time of creation of a yellow interface as opposed to the blue icon of a regular interface. The advantage of using a yellow interface is to avoid the creation of  Models each time you need to use it in an interface. Since they are temporary, they are not a part of the data model and hence don’t need to be in the Model. So let’s begin and start creating our yellow interface! Pre-requisites : Oracle 10g Express Edition with *SQL Plus, Oracle Data Integrator 11g. Open *SQL Plus and create a new table  Sales ...

Synchronous and Asynchronous execution in ODI

In data warehouse designing, an important step is to deciding which step is before/after. Newly added packages and required DW data must be analyzed carefully. Synchronous addings can lengthen ETL duration. Interfaces, procedures without generated scenario cannot be executed in parallel. Only scenario executions can be parallel in ODI. Default scenario execution is synch in ODI. If you want to set a scenario to executed in parallel then you will write “-SYNC_MODE=2″ on command tab or select Synchronous / Asynchronous option Asynchronous in General tab. I have created a package as interfaces executes as; INT_JOBS parallel  INT_REGIONS synch  INT_REGIONS synch  INT_COUNTRIES synch  INT_LOCATIONS parallel  INT_EMPLOYEES parallel (Interfaces are independent.) Selecting beginning and ending times and durations from repository tables as ODI 11g operator is not calculating these values. It is obvious in ODI 10g operator. SELECT    sess_no...