Quick Prep Big Data Interview Archives | Page 17 of 23 | 800+ Java & Big Data Interview Q&As

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21: Q121 – Q124 Scala Extractor Interview Q&As

Q121 What is an extractor object in Scala? A121 An extractor object is an object with an unapply method. The apply method is like a constructor which takes arguments and creates an object, the unapply takes an object and tries to give back the arguments. … Read more ›...

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21: Q138 – Q142 AWS data lakes overview Interview Q&As

Q138. What are the basic considerations when building a data lake on an AWS platform?
A138.

1. Ingestion into S3 (i.e. Simple Storage Service) from different source systems. E.g. csv/xml/json files extracted from source systems, streamed data from source systems via message queues/topics,

…

22: 50+ SQL scenarios based interview Q&As on recursion

This extends Common Table Expressions (i.e. CTE) in SQL using the “WITH” clause. You can try the example on DB Fiddle. Use MySQL v8.0 or later. Scenario: 1 Given a table like this with each entry with two dates (i.e. from_date & … Read more ›...

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22: PySpark Row object Interview Q&As with tutorials

This extends PySpark map vs flatMap Interview Q&As with tutorials. Q01. What is a Row object in PySpark? A01. Row can be used to create a row object by using named arguments. The previous example can be represented with a Row object. … Read more ›...

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22: Python Duck typing tutorial

Q. What is duck typing? A. Duck typing is a feature of a type system where the semantics of a class is determined by its ability to respond to some message. It is a term used in dynamic languages that do not have strong typing. … Read more ›...

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22: What are the uses of underscore i.e _ in Scala?

The underscore (_) is one of the symbols used very widely in Scala. It is used as a Wild card, Place holder, Except, Ignore etc. Module Import Used as a wild card, … Read more ›...

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23: 50+ SQL scenarios based interview Q&As – Join counts

One of the common SQL interview questions is to quiz your understanding of SQL joins. In this let’s look at joins example with two scenarios.

Venn Diagram

Joins can be specified as a venn diagram shown below:

But, it gets a bit more tricky when you consider the below scenarios:

Scenario 1: When both input tables don’t have duplicate values.

…

23: Python coding questions – magic method, generator & debugging

Q1. What will be the output of the below code & why?

def append(ele, to=[]):
    to.append(ele)
    return to

def main():
    list_1 = append(33)
    print(list_1)

    list_2 = append(44)
    print(list_2)

    list_3 = append(55)
    print(list_3)
    
if __name__ == "__main__":
    main()

def append(ele, to=[]):

to.append(ele)

return to

def main():

list_1 = append(33)

print(list_1)

list_2 = append(44)

print(list_2)

list_3 = append(55)

print(list_3)

if __name__ == "__main__":

main()

A1. The output will be

[33]
[33, 44]
[33, 44, 55]

[33]

[33, 44]

[33, 44, 55]

The to=[] in the append(…) function make use of the defaults. When the defaults get called for the first time it is initialised and then subsequent calls will append the values...

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23: Scala Traits, Mixins, self-type annotation & DI with Cake pattern

Q01. What is a trait in Scala? A01. In Scala, trait is a collection of abstract and non-abstract methods. You can create trait that can have all abstract methods or some abstract and some non-abstract methods. A variable that is declared either by using val or var keyword in a...

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24: 50+ SQL scenarios based interview Q&As – Window Query

If you want to learn the basics of SQL analytics function, first read SQL analytic functions interview questions – Part 1 | SQL analytic functions interview questions – Part 2 | SQL analytic functions interview questions – Part 3

Given the below data:


event_id   event_type   city          country       duration_seconds
----------------------------------------------------------------------
1          login        sydney        australia        9
2          logout       melbourne     australia        8
3          login        sydney        australia        5
4          login        melbourne     australia        9
5          login        california    usa              8
6          logout       new york      usa              6
7          login        california    usa              5
8          login        new york      usa              2

event_id event_type city country duration_seconds

----------------------------------------------------------------------

1 login sydney australia 9

2 logout melbourne australia 8

3 login sydney australia 5

4 login melbourne australia 9

5 login california usa 8

6 logout new york usa 6

7 login california usa 5

8 login new york usa 2

Q1.

…

24: Python coding questions – formatting, join, regex & write a program

This extends 23: Python coding questions – part 1. You can either set up your Python environment or use an online interpreter like www.online-python.com. Q1. Given the below variable values, name = “John” age = 23 how will you print “ … Read more ›...

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25: 50+ SQL scenarios based interview Q&As – get the last non null value

The below SQL problem can be practiced on MySQL database at db-fiddle or database of your choice. Q1. Given the below data, how will you find the last non null values for each event_id?


event_id   date           city             country      event_type
---------------------------------------------------------------------
1          2023-02-02     sydney           australia       0
1          2023-02-03     null             australia       1
1          2023-02-04     melbourne        australia       2
2          2023-02-06     california       usa             1
2          2023-02-07     new york         usa             null
2          2023-02-08     null             usa             4

event_id date city country event_type

---------------------------------------------------------------------

1 2023-02-02 sydney australia 0

1 2023-02-03 null australia 1

1 2023-02-04 melbourne australia 2

2 2023-02-06 california usa 1

2 2023-02-07 new york usa null

2 2023-02-08 null usa 4

Create table & insert data

DROP TABLE IF EXISTS event;

CREATE TABLE IF NOT EXISTS event
(
  event_id int,
  date date,
  city varchar(20),
  country varchar(20),
  event_type varchar(20)
);  

INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-02', 'sydney', 'australia', '0' );
INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-03', null, 'australia', '1' );
INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-04', 'melbourne', 'australia', '2' );
INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-06', 'california', 'usa', '1' );
INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-07', 'new york', 'usa', null );
INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-08', null, 'usa', '4');

DROP TABLE IF EXISTS event;

CREATE TABLE IF NOT EXISTS event

(

event_id int,

date date,

city varchar(20),

country varchar(20),

event_type varchar(20)

);

INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-02', 'sydney', 'australia', '0' );

INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-03', null, 'australia', '1' );

INSERT INTO event(event_id,date,city,country,event_type) VALUES (1, '2023-02-04', 'melbourne', 'australia', '2' );

INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-06', 'california', 'usa', '1' );

INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-07', 'new york', 'usa', null );

INSERT INTO event(event_id,date,city,country,event_type) VALUES (2, '2023-02-08', null, 'usa', '4');

Solution In order to ignore null values “CASE WHEN...

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25: Python protocol classes tutorial & interview Q&As

This post extends Python Abstract Base Classes (i.e. ABC) tutorial and Python Data modelling tutorial – Dunder or Magic Methods, Duck Typing & Protocols Q1. What is a Python protocol class ? A1. In Python, … Read more ›...

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« 1 … 13 14 15 16 17 18 19 20 21 … 23 »

Blog Archives

21: Q121 – Q124 Scala Extractor Interview Q&As

21: Q138 – Q142 AWS data lakes overview Interview Q&As

22: 50+ SQL scenarios based interview Q&As on recursion

22: PySpark Row object Interview Q&As with tutorials

22: Python Duck typing tutorial

22: What are the uses of underscore i.e _ in Scala?

23: 50+ SQL scenarios based interview Q&As – Join counts

23: Python coding questions – magic method, generator & debugging

23: Scala Traits, Mixins, self-type annotation & DI with Cake pattern

24: 50+ SQL scenarios based interview Q&As – Window Query

24: Python coding questions – formatting, join, regex & write a program

25: 50+ SQL scenarios based interview Q&As – get the last non null value

25: Python protocol classes tutorial & interview Q&As

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