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00: 13 Data modelling interview Q&As – Fact Vs Dimension, CDC, SCD, etc – part 1

Q1. What is dimensional modelling in a Data Warehouse (i.e. DWH)?
A1. A dimensional model is a data structure technique optimised for Data Warehousing tools (i.e. OLAP products). The concept of Dimensional Modelling is comprised of Fact and Dimension tables.

A “Fact” is a numeric value (i.e. aka a measure) that a business wishes to count or sum. A “Dimension” is essentially descriptive value in text for getting at the facts.… Read more ...

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00: 13 Data modelling interview Q&As – Fact Vs Dimension, CDC, SCD, etc – part 2

This extends Q1 to Q5 at 13 Data Warehouse interview Q&As – Fact Vs Dimension, CDC, SCD, etc – part 1. Q6. What is a Factless Fact table? A6. From the above store sales example we know that fact table is a collection of many facts having multiple keys joined…

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01: Data Backfilling interview questions & answers

Q1. What is data backfilling? A1. Backfilling data is a process of reactively processing any missing data for a past time window. Q2. Why do you need to backfill data? A2. There are two types of data loads from source systems to target (aka sink) systems via ETL pipelines: 1)…

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03: Databricks – Spark SCD Type 1

Prerequisite: Extends Databricks getting started – Spark, Shell, SQL.

What is SCD Type 1

SCD stands for Slowly Changing Dimension, and it was explained in 10 Data warehouse interview Q&As.

Step 1: Remove all cells in the notebook with the “x” and then confirm or create a new Python notebook. If the cluster is not running as it auto terminates after 2 hours, create a new cluster and attach it to the notebook.… Read more ...

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04: Databricks – Spark SCD Type 2

Prerequisite: Extends 03: Databricks – Spark SCD Type 1. What is SCD Type 2 SCD stands for Slowly Changing Dimension, and it was explained in 10 Data warehouse interview Q&As. Step 1: You may have to reattach the cluster to the notebook as clusters auto terminate after 2 hours. Create…

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04a: Databricks – Spark SCD Type 1 with Merge

Prerequisite: Extends 03: Databricks – Spark SCD Type 1. What is SCD Type 1 SCD stands for Slowly Changing Dimension, and it was explained in 10 Data warehouse interview Q&As. Step 1: You may have to reattach the cluster to the notebook as clusters auto terminate after 2 hours. Create…

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04b: Databricks – Spark SCD Type 2 with Merge

Prerequisite:…

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05: Q37-Q41 – Data lake & metadata interview Q&As

Q37. What is a Data Lake? A37. A data lake is a storage repository that holds a vast amount of structured, semi-structured, and unstructured raw data in its native format (aka pristine condition). The data structure and requirements are not defined until the data is needed. You can also call…

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10 ERD (Entity-Relationship Diagrams) Interview Q&As

Q01. Can you describe a business domain of a Telecom company offering multiple services to its customers? A01. A Telecom company will have entities such as Customer, Account, Subscriptions & Products representing a business domain. 1) Each customer entity has a name, physical address, and an email address. 2) A…

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Apache Hive for Slowly Changing Dimension (i.e. SCD) interview Q&As

Q1. What is a Slowly Changing Dimension (i.e. SCD)? A1. SCD means the dimensions that change slowly over time, rather than changing on regular basis. For example, change in customer name or address. There are different types of changing dimensions, and type 1 & type 2 are the most common….

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Java Developer & Architect Interview Q&As

Java & Big Data Tutorials

Prepare to fast-track & go places

FAQs are marked with 🔥 as some questions are not only more popular with the interviewers, but also required to build robust systems. If you are an interviewer, cover well rounded topics to judge real experience.

Don't be overwhelmed by the number of questions as the technology stacks are so vast. The quality of the answers you provide to some of the key technical & open-ended questions along with your soft skills & attitude will go a long way in getting the job offers.

Note: Some Q&As belong to more than one category.
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