Top AWS Redshift Interview Questions frequently asked interview questions.

In this post we will look at AWS Redshift Interview questions. Examples are provided with explanations.

What is AWS Redshift?

Amazon Redshift is a fully managed, petabyte-scale data warehouse service in the cloud. This enables you to use your data to acquire new insights for your business and customers. It is a data warehouse product which forms part of the larger cloud-computing platform Amazon Web Services. The name means to shift away from Oracle, red being an allusion to Oracle, whose corporate color is red and is informally referred to as "Big Red." It is built on top of technology from the massive parallel processing (MPP) data warehouse company ParAccel (later acquired by Actian),[3] to handle large scale data sets and database migrations

Q: What are the advantage of using Amazon Redshift ?

High performance - It is observed that it is 10 times faster than Hadoop.
Cost Effective - The price is extremely affordable if we buy 3-year reservation.
Easy operation - It has been very reliable and self-managed. Very easy to maintain and operate.

Q: How to alter column data type in Amazon Redshift ?

Following the command to alter the column data type in Amazon Redshift-

ALTER COLUMN column_name TYPE new_data_type

Q: How to show tables in Amazon Redshift ?

Below is the command to list tables in a public schema :

SELECT DISTINCT tablename
FROM pg_table_def
WHERE schemaname = 'public'
ORDER BY tablename;

Below is the command to describe the columns from a table called table_data

SELECT *
FROM pg_table_def
WHERE tablename = 'table_data'
AND schemaname = 'public';

Q: How to convert epoch to datetime redshift ?

We will need to use the sql query to get the timestamp.

select timestamp 'epoch' + your_timestamp_column * interval '1 second' AS your_column_alias
from table_name

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