There are three PostgreSQL character types:
char: fixed length. varchar: variable length with optional limit. text: variable length without limit. char and varchar need an argument n to specify the characters length or limit.
char(n) The char(n) type stores fixed length strings.
If the string you are adding is shorter than n, spaces are added to make up the difference. For example, if ‘n’ is 7 and the string is house, which has 5 characters, the following value will be added: house .

The correlation is a statistical measure that shows how closely related are two sets of values.
The most used correlation measure used is the Pearson’s Correlation Coefficient. The Pearson’s Correlation Coefficient gives:
a value of 1 for a perfect correation. a value of 0 for no correlation. a value of -1 for a perfect negative correlation Examples of Positive and Negative Correlation:
Positive Correlation: marketing expenditure and sales, price of a competitor product and sales.

Google BigQuery is a serverless scalable data warehouse that is available on Google Cloud. The greatest advantage of Google BigQuery is that it allows companies to store and analyze big data without having to setup and manage infrastructure.
Companies can analyze and transform data using famliar ANSI-standard SQL. Google BigQuery can be accessed using an REST API, the Google BigQuery web interface (browser) and a command line tool.
By decoupling storage and compute, different layers of the architecture can be executed and scale independently.