Technology Questions

User defined data-types in SQL is an extension to the base SQL server data-types by provision of a descriptive name.

We use them to format the database and segregate specific repetitions of rows and columns in the database.

With static IP addressing, a computer (or other device) is configured to always use the same IP address. With dynamic addressing, the IP address can change periodically and is managed by a centralized network service

Optimized code tends to run faster and make more efficient use of the system’s resources. Optimized codes are also less susceptible to errors and take lesser space in memory and in file size.

There are lots of ways to solve the issue of callback hells:

1. Modularization: break callbacks into independent functions
2. Use a control flow library, like async
3. Use generators with Promises
4. Use async/await (note that it is only available in the latest v7 release and not in the LTS version)

Amazon S3 provides uploading of large files and retrieve small offsets for end-to-end transfer data rates. The large file gets stored into small files that are smaller in size. Amazon S3 stores multiple of files together in a bundle or in a compressed form, For example in .gzip or .gz format and then convert them into Amazon S3 objects. The files get uploaded on the Amazon server by the use of FTP or another protocol and then retrieved through the HTTP GET request. The request includes the defined parameters like URL, offset (byte-range) and size (length).

SELECT DISTINCT(salary) FROM emp as e1 

WHERE (3) = (SELECT COUNT(DISTINCT(salary)) FROM emp as e2  WHERE e1.salary <= e2.salary)

MIME - Multi-purpose Internet Mail Extensions. 

MIME types represents a standard way of classifying file types over Internet. 

Web servers and browsers have a list of MIME types, which facilitates files transfer of the same type in the same way, irrespective of operating system they are working in.

A MIME type has two parts: a type and a subtype. They are separated by a slash (/). 

MIME type for Microsoft Word files is application and the subtype is msword, i.e. application/msword.

In a mapreduce job the master pings each worker periodically. In case a worker does not respond to that system then the system is marked as failed. Even completed tasks are rescheduled because the output was stored in a in a local disk of a worker which failed. Hence mapreduce is able to handle large-scale failures easily by simply restarting a task. The master node always saves itself at checkpoints and in case of any failure it simply restarts from that checkpoint.