Technology Questions

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).

EXECUTE IMMEDIATE command can be used to call DDL statements. 

Example:

BEGIN

EXECUTE IMMEDIATE  'TRUNCATE TABLE employee';

END;

There are four important files in order to make a bootable Windows XP operating system. These are Ntldr, Ntdetect, Boot.ini and Ntfs.sys

Function: A Function is a block of statement which perform some operation.

Declaring the function before using the function in program is known as implicit declaration of the function.

For Example::

int bar(void); // function (forward) declaration

int main(void) {

bar(); // bar was declared, the compiler has all the info

return foo(123); // foo not yet known; impl. decl. warning

}

// not previously declared function definition

int foo(int a) {

return a;

} 

// previously declared function definition

int bar() {

return 321;

}

A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests. Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

Trigger allows us to execute a batch of SQL code when an insert, update or delete command is executed against a specific table.

Triggers are special types of stored procedures that are defined to execute automatically in place of or after data modifications. They can be executed automatically on the insert, delete and update operation.

The knowledge of Joins is a MUST for every interviewee. Most SQL programmers have used inner join and  outer join[left/right]; but the catch point here is to also mention cross join and self-join.

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)