Answer
Extraction, Transformation and loading
are different stages in data warehousing.
Extraction
In this phase, data is extracted from the source
and loaded in a structure of data warehouse.
Transformation
After extraction cleaning process happens for
better analysis of data.
Loading
After cleaning, data is loaded in the structure of
data warehousing.
Question - What is Data mining?
Answer
Data mining is a process of analyzing
current data and summarizing the information in more useful manner.
It is useful in analyzing how good business is going and also helps
in forecasting business status.
Question - What are indexes?
Answer
Index can be thought as index of the
book that is used for fast retrieval of information.
Index
uses one or more column index keys and pointers to the record to
locate record.
Index is used to speed up query
performance.
Both exist as B-tree structure.
Kind
of the indexes are clustered and non-clustered.
Question - Explain the types of indexes?
Answer
Clustered index
Non-clustered
Clustered index
Clustered index exists as sorted row on
disk.
Clustered index re-orders the table
record.
Clustered index contains record in the leaf level
of the B-tree.
There can be only one Clustered index
possible in a table.
Non-clustered
Non-clustered index is the index in which
logical order doesn’t match with physical order of stored data on
disk.
Non-clustered index contains index key to the table
records in the leaf level.
There can be one or more
Non-clustered indexes in a table.