Cloud computing is a metaphor used for internet. It provides on-demand access to virtualized IT resources that can be shared by others or subscribed by you. It provides an easy way to provide configurable resources by taking it from a shared pool. The pool consists of networks, servers, storage, applications and services.

Cloud computing consists of 3 layers in the hierarchy and these are as follows:

1. Infrastructure as a Service (IaaS) provides cloud infrastructure in terms of hardware like memory, processor speed etc. 

2. Platform as a Service (PaaS) provides cloud application platform for the developers. 

3. Software as a Service (SaaS) provides cloud applications which are used by the user directly without installing anything on the system. The application remains on the cloud and it can be saved and edited in there only.

Data warehouse

- It is a decision support database system for the purpose of organizational needs. 

-It is non volatile, integrated and time variant collection of data

Operational Data Stage

- It is an integrated collection of information. 

-It can contain 90 days of information at maximum.

-ODS supports dynamic data.

Sequence numbers can be generated in Datastage using certain routines. They are

-KeyMgtGetNextVal

-KeyMgtGetNextValConn

- Physical Data Integration is all about creating new system that replicates data from the source systems.

- This process is done to manage the data independent of the original system.

- Data Warehouse is the example of Physical Data Integration.

- The benefits of PDI include data version management, combination of data from various sources, like mainframes, flat files, databases.

- A separate system is needed for handling vast data volumes.

- UDAI places the data in the source systems.

- A set of views are defined for providing access the unified view to the clients / customers.

- Zero latency of data can be propagated from the source system.

- The generated consolidated data need not require separate storage space.

- Data history and version management is limited and applied only to the similar type of data.

- Accessing to the user data overloads on the source systems.

Look for the existence of the following items:

- Generic Data Models

- An Enterprise Data Platform

- Identify the Data Sources

- Selection of a MDM Product

- Implementation of a Customer Master Index or appropriate alternative

•  NO_CACHE – It is used for not caching values.


•  PRE_LOAD_CACHE – Result column preloads and compares the column into the memory, prior to executing the lookup.


•  PRE_LOAD_CACHE is used when the table can exactly fit in the memory space.


•  DEMAND_LOAD_CACHE – Result column loads and compares the column into the memory when a function performs the execution.


•  DEMAND_LOAD_CACHE is suitable while looking up the highly repetitive values with small subset of data.