IS-ICT223

1. DATA WAREHOUSE

2. WHAT IS DATA WAREHOUSE?
• In computing, a data warehouse (DW or DWH), also known as
an enterprise data warehouse (EDW), is a system used
for reporting and data analysis, and is considered a core
component of business intelligence.
• The data stored in the warehouse is uploaded from
the operational systems (such as marketing or sales). The data
may pass through an operational data store and may require data
cleansing
• ETL based Data warehousing

5. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
1. Disaster Recovery (DR)
• When you use cloud storage, data is at a reduced risk of system failure since all data
is stored and backed-up on an external devise often thousands of miles away from
your own location. This means you avoid expensive data retrieval that follows an all-
too-common hard-drive malfunctioning. Cloud providers automate the backup
process for you. Therefore there is no need to back-up your data on an external
devise yourself. You save time and stress as a result.

6. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
2. Access your data anywhere
Since your data is stored remotely you can access it whether you are in Manchester or
Madrid. This is especially helpful if your work requires frequent travel or if your team is
located in different time-zones.
Cloud-storage also helps the collaborative process when your team is spread out
across the globe. Cloud storage makes it easy for employees to login and access other
team members’ work regardless of location and distance that separates team
members. When you use cloud storage you’re not restricted by place or medium and
your employees are able to work from home or abroad as a result.

7. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
3. Low cost
Cloud storage eliminates the need to pay for software licences and updates since all
this is included in one global monthly price. Cloud storage also avoids the need to
invest in expensive server infrastructure since the cloud company provides this off-site
for you. You eliminate the need to pay a dedicated storage professional in-house
since you are effectively outsourcing this to the cloud storage company. Unlike in-
house employees, you do not need to pay the cloud storage company sick-pay or
holiday pay.

8. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
4. Scalability
Cloud storage eliminates the need to pay for software licences and updates since all
this is included in one global monthly price. Cloud storage also avoids the need to
invest in expensive server infrastructure since the cloud company provides this off-site
for you. You eliminate the need to pay a dedicated storage professional in-house
since you are effectively outsourcing this to the cloud storage company. Unlike in-
house employees, you do not need to pay the cloud storage company sick-pay or
holiday pay.

9. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
4. Scalability
Cloud storage eliminates the need to pay for software licences and updates since all
this is included in one global monthly price. Cloud storage also avoids the need to
invest in expensive server infrastructure since the cloud company provides this off-site
for you. You eliminate the need to pay a dedicated storage professional in-house
since you are effectively outsourcing this to the cloud storage company. Unlike in-
house employees, you do not need to pay the cloud storage company sick-pay or
holiday pay.

10. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Advantage
5. Security
• Professional cloud storage firms typically offer far better data security than is
otherwise available to small businesses through efforts of their own. Cloud storage
companies offer password protected data storage. Data is then sent over the
internet using encryption technology. This ensures the highest standards of security
are upheld.

11. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Disadvantage
1. Lack of Total Control
• Since data is held offsite by a company you do not control, you lack the ability to
control and customize your data storage set-up. This likely to be an issue for larger
businesses who have complex storage needs. This typically requires a level of
customization that cloud data storage companies are unfortunately unable to
accommodate.

12. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Disadvantage
2. Difficult to migrate
Once you’ve signed up and started using one particular cloud storage provider, it is difficult to
migrate data to another cloud provider later on.
This is a phenomenon known as 'vendor lock-in'. Vendor lock-in is particularly a problem for
medium-to-large size businesses who store massive amounts of data with one cloud provider.
If you run into problems with that provider it may be problematic to switch to another
provider due to the sheer size of data and related complexities of making a move.
Since data is held offsite by a company you do not control, you lack the ability to control and
customize your data storage set-up. This likely to be an issue for larger businesses who have
complex storage needs. This typically requires a level of customization that cloud data storage
companies are unfortunately unable to accommodate.

13. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Disadvantage
3.Requires Internet
If your Internet connection fails, so does your access to remotely stored data.
Internet failure thus leads to costly downtime when your business heavily relies on
cloud storage. Furthermore if your Internet connection is slow you will need to wait a
long time in order to access your remotely stored data.
No cloud provider offers an outage free service. By way of example, in 2014 ‘Dropbox’,
a major cloud storage provider experienced an outage lasting two days. This caused a
lot of inconvenience for many of Dropbox’s customers.

14. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Disadvantage
4. Security and privacy have been an issue
Cloud storage means handing over the control of confidential information to a third
party company. Before you transfer data to a cloud storage provider you must have
utter faith this company is capable of keeping your data secure. In the past things
have been known to go wrong with cloud storage companies.

15. PROS AND CONS OF DATA WAREHOUSE
USING CLOUD STORAGE
Disadvantage
5. Fixed contracts can be a problem
Some cloud storage suppliers may try to fix you into a long term contract. This may be
disadvantageous if your data storage needs reduce meaning you must now pay for
storage you're not even using.

16. • The typical extract, transform, load (ETL)-based data warehouse uses staging, data integration, and
access layers to house its key functions. The staging layer or staging database stores raw data extracted
from each of the disparate source data systems. The integration layer integrates the disparate data sets
by transforming the data from the staging layer often storing this transformed data in an operational
data store (ODS) database. The integrated data are then moved to yet another database, often called
the data warehouse database, where the data is arranged into hierarchical groups, often called
dimensions, and into facts and aggregate facts. The combination of facts and dimensions is sometimes
called a star schema. The access layer helps users retrieve data.
• The main source of the data is cleansed, transformed, catalogued, and made available for use by
managers and other business professionals for data mining, online analytical processing, market
research and decision support.[6] However, the means to retrieve and analyze data, to extract,
transform, and load data, and to manage the data dictionary are also considered essential components
of a data warehousing system. Many references to data warehousing use this broader context. Thus, an
expanded definition for data warehousing includes business intelligence tools, tools to extract,
transform, and load data into the repository, and tools to manage and retrieve metadata.