An operational system of record whose
function it is to capture the transactions of the
Business; sometimes called Legacy Systems in mainframe environment. Most
preferably source system stores only current data; so no historical data is
preserved here. These systems are input to data warehouse and data is called
source data. Source data can also exist in the form of flat files, excel etc.
Data
Staging Area
A storage area and set of processes
that clean, transform, combine, de-duplicate, and prepare source data for use
in the data warehouse. The data staging area is everything in between the
source system and the presentation server. Input to staging area can be from
multiple data sources and its always good to have all source data at one place
before loading into the data warehouse or presentation server. Data staging
area may contain a system of flat files also which are letter used to load into
data warehouse system.
Presentation
Server
The target physical machine on which
the data warehouse data is organized and stored for direct querying by end
users, report writers, and other applications. Storage in the presentation area
will mostly be in RDBMS tables which are later used to analysis of data by querying
database tables.
Dimensional
Model
A specific discipline for modeling
data that is an alternative to entity-relationship (E/R) modelling. A
dimensional model contains the same information as an E/R model but packages
the data in a symmetric format whose design goals are user understandbility, query
performance, and resilience to change.
The main components of a dimensional
model are fact tables and dimension tables. A fact table is the primary table
in each dimensional model that contains measurements of the business. Every Fact
table contains keys from dimensional tables called as foreign keys.
Dimensional tables mostly contain textual
attributes (fields) and a primary key serves as foreign key in fact tables.
Data
Mart
A logical subset of the complete data
warehouse & it is specific to one subject area like Sales data mart etc. A
data warehouse will be union of all data marts & will contain multiple fact
tables from different data marts and fact tables from multiple data marts can be
joined on the basis of conformed dimensions. A conformed dimension is one which
definition across data marts does not change; foe eg. Time dimension, Geography
dimension.
Data
Warehouse
The queryable source of data in the
enterprise. The data warehouse is nothing more than the union of all the
constituent data marts. A data warehouse is fed from the data staging area.
Operational
Data Store (ODS)
Stores Current data and recent
history like in bank ATM ODS where bank stored Current balances and recent
history; also no bank would likely to access data warehouse for mini
transaction at ATM and so they go for ODS. And as ODS needs continuous
operational access and updates, it should be housed outside of data warehouse.
End
User Application/Tools
A collection of tools that query,
analyze, and present information targeted to support a business need.
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