Dimensional Modeling Nomenclature

Normalization vs Denormalization

Normalization:

PROS:

• When writes are more than reads
• Vertically divided among columns i.e. split-ted into multiple tables.
• Updates and Inserts will be effective since no duplicates.
• Less use of heavy DISTINCT or GROUP BY queries since no duplicates.

CONS:

• JOINS due to multiple tables.
• Index strategies are not effective due to joins.

De-Normalization:

PROS:

• When reads are more than writes.
• SELECTS are very fast since we avoid JOINS and effective because of index strategies works very well with selective columns.

CONS:

• Updates and INSERTS becomes costly.

In real time , you should be good enough to choose the most read or most write tables to apply this concepts.

Unix Script to generate files based on unique values of a field

Below file has different mobile companies. I need to generate the files dynamically based on the unique values of the field.I can have blank values also.But I should not generate files for those.

Input:

Generate the Unique values :

Script to generate files based on the unique values. Here -z in the if condition represents the check for empty variable.

Output:

Remove Leading and Trailing spaces/tabs from each line in Unix using sed command

Input:








Command:

Output: