Question { 4819 }

Give the reasoning behind using an index.

Answer

Its as simple as why do we need an index page in front of a
book. Whenever we wish to read a scpecific text from the
book, we'll first check the index and locate where that
specific text is. Similarly when create an index it enables
the queries to locate praticular row or entity in a table
by directly refering to the index instead of searching the
entire table. Whenever a table is created with a primary
key, an index ia automatically created on the primary key
column which makes easier access of table entries. When you
execute query say( select * from student where
student_id=10;), your query will first hit the index
(primary index on primary key column) and then will retrive
the corresponding row from the table. If there's no such
entry in the table, it'll return an empty result set
without searching the table.

Question { Honeywell, 5253 }

OLAP architecture?

Answer

OLAP architecture may be
->Generic Two-Level Architecture
->Independent Data Mart
->Dependent Data Mart and ODS
->Logical Data Mart and active Warehouse
->Three-Layer architecture.
For better understanding of these types in detail. please
surf through.

Question { 3292 }

What is a ETL/ How does Oracle support the ETL process?

Answer

ETL stands for Extract transform and load.
In general the entire ETL process is only SQL scripts
executed against the database. Oracle being a Database
which favours ETL through SQL scripts.