ETL Testing

ETL is short for extract, transform, load, three database functions that are combined into one tool to pull data out of one database and place it into another database.

Q.1 In third-party management, how do we use ETL?
Different types of suppliers are always given different types of application development by large organisations. Everything cannot be managed by a single vendor. We'll use the example of a telecommunications project where one business is in charge of billing and another is in charge of CRM. If a CRM company requires data from a billing company, the company will now obtain the data flow through another company. The ETL method is used to load the data.
Q.2 What role does ETL play in a data migration project? Please explain.
In most Data Migration Projects, ETL tools are employed. If a company previously managed data in Oracle 10g and now wishes to use SQL Server Cloud Database, data must be moved from source to target. ETL tools are extremely handy for this type of transfer. It is an extremely time-consuming procedure to write ETL code. To make things easier, we employ an ETL tool that converts PL SQL or T-SQL code into simple PL SQL or T-SQL code. As a result, the ETL procedure is beneficial in data migration projects.
Q.3 What exactly are the ETL flaws?
Source Bugs Load Condition Bugs Calculation Bugs ECP related Bugs User-Interface Bugs
Q.4 What is ETL partitioning?
For optimal speed, transactions must always be separated. Partitioning refers to the same procedures. It just ensures that the server may access the sources directly via numerous connections.
Q.5 What exactly is the ETL Pipeline?
A data extraction, transformation, and loading (ETL) pipeline is a series of operations for extracting data from one system, transforming it, and loading it into a database or data warehouse. Data warehousing solutions, which include both business data warehouses and subject-specific data marts, require ETL pipelines. Data migration solutions leverage ETL pipelines as well. ETL pipelines are built by data warehouse/business intelligence engineers.
Q.6 What is the Data Pipeline, and how does it work?
Any group of processing elements that transport data from one system to another is referred to as a data pipeline. Any application that uses data to provide value can benefit from a Data Pipeline. It can be used to integrate data across applications, develop data-driven web products, and conduct data mining operations. The data pipeline is built by data engineers.
Q.7 Where does the ETL Testing staging take place?
During the data integration process, the staging site is a temporary storage facility. Data is thoroughly evaluated for redundancy and duplication in this location.
Q.8 What exactly is ETL?
The Extracting, Transforming, and Loading (ETL) of data from any external system to the desired location is referred to as ETL. The core three steps in the data integration process are as follows. In the ‘Extracting' stage, data is extracted from the source file and transported to the required target file; in the ‘Transforming' stage, data is transported to the required target file; and in the ‘Loading' stage, the file is loaded to the target system in the given format.
Q.9 Why is ETL Testing Necessary?
To maintain track of the efficiency and speed of the operation when data is being transferred from one system to another To attain the best results in a short amount of time
Q.10 What is an ETL Tester's job description?
An ETL Tester is a person who tests the end-to-end flow of Requires a thorough understanding of ETL tools and methods. During the testing phase, SQL queries must be written for numerous scenarios. Should be able to perform various types of tests and maintain track of the process's other features. Quality inspections must be performed on a regular basis.
Q.11 What are the different tools that are utilised in ETL?
Cognos Decision Stream Oracle Warehouse Builder Business Objects XI SAS Business Warehouse SAS Enterprise ETL Server
Q.12 Define ETL (Extract, Transform, and Load) processing.
ETL Testing Process: Despite the numerous ETL technologies available, ETL Testing follows a straightforward testing procedure. It's just as crucial as integrating the ETL tool into your company. The testing process can be made considerably easier if you have a well-defined ETL Testing approach. As a result, this step must be performed before you begin integrating data with the ETL tool you've chosen. A group of professionals from the programming and development teams will begin writing SQL statements as part of the ETL Testing process. They can be customised by the development team based on the requirements.
Q.13 Explain the ETL Testing process stages.
Understanding the business structure and its specific requirements is the first step in analysing requirements. Estimating the time and skill required to complete the method through validation and testing. Testing environment planning and design: An ETL environment is designed and worked up based on the inputs from the estimation. Preparation and execution of test data: Data for the test is prepared and executed according to the requirements. A brief summary report is provided following the completion of the test run for improvising and concluding.
Q.14 What exactly does ETL Testing entail?
The following are examples of ETL testing: Checking to see if the data has been transformed correctly according to the business requirements. Ensure that the predicted data is put into the data warehouse without being truncated or losing data. Ensure that any faulty data is reported and replaced with default values by the ETL programme. To optimise scalability and performance, make sure the data loads inside the required time limit.
Q.15 List a few ETL bugs.
Calculation Bug User Interface Bug Source Bug Load Condition Bug ECP-related Bug
Q.16 What is the definition of fact? What are the different kinds of facts?
A multi-dimensional model that incorporates the measurements to be studied has a central component called fact. Dimensions are linked to facts. The following are examples of facts: Factors that make a difference Facts that are semi-additive Factors that aren't additive
Q.17 What are OLAP Cubes and Cubes?
Cubes are data processing units made up of data warehouse fact tables and dimensions. They offer a multi-dimensional evaluation. OLAP Cubes contain extensive data in a multi-dimensional manner for reporting reasons, and OLAP stands for "Online Analytics Processing." They are made up of facts termed "measures" that are organised into dimensions.
Q.18 Mention the various forms of Data Warehouse software. What are the distinctions between data mining and data warehousing?
The following are examples of data warehouse applications: Analytical Processing of Information Data Exploration Data mining is the process of extracting hidden predictive information from huge datasets and interpreting the results, whereas data warehousing may employ a data mine to speed up the analytical processing of data. The practise of consolidating data from various sources into a single repository is known as data warehousing.
Q.19 What is an ETL cycle's three-layer architecture?
The ETL is made up of three layers: The staging layer is used to hold data that has been extracted from various data source systems. Data Integration Layer: The data from the staging layer is transformed and moved to a database by the integration layer. The data in the database is organised into hierarchical categories, commonly referred to as dimension, as well as facts and aggregate facts. A schema is a data warehousing system's collection of facts and dimension tables. End-users access the data through the access layer in order to generate analytical reports.
Q.20 What is Business Intelligence (BI)?
The act of gathering raw business data and translating it into a meaningful vision that is more beneficial for business is known as business intelligence.
Q.21 What ETL tools are currently available on the market?
The following are some of the most popular ETL tools on the market: Websphere is an IBM product. Power Center for DataStage Informatica Business Objects Data Service (SAP) Oracle - Warehouse Builder BODS SAS - Data Integration Studio Clover ETL is a free and open source project.
Q.22 When does the staging area come into play in the ETL process?
The staging area serves as a link between the data sources and the data warehouse/data marts systems. It's a location where data is temporarily kept throughout the data integration process. Area data is cleansed and checked for duplication in staging. The staging area is intended to provide a variety of benefits, but the major purpose is to use it. It's utilised to boost productivity, ensure data integrity, and aid data quality processes.
Q.23 What is a Data Mart, exactly?
A Data Mart is a basic Data Warehouse that focuses on a specific functional area. It only gathers the information from a few sources. For example, data marts may exist in an organisation for marketing, finance, human resources, and other departments that hold data pertaining to their respective functions.
Q.24 What exactly is the purpose of ETL testing?
We are transferring many systems from outdated technology to new technology in today's world. We must also migrate data from the old DBMS to the new DBMS as part of the migration procedures. As a result, there's a lot of pressure to make sure the data on the target side is correct.
Q.25 In Data Warehousing, how do we use ETL?
The ETL is most typically used in Data Warehousing. For the purpose of constructing the data warehouse, the user retrieves both historical and current data. The data in the data warehouse is a mix of historical and transactional information. The data warehouse's data source could be varied. We need to gather data from a variety of sources and feed it into a single target system, commonly known as a data warehouse.
Q.26 What does ETL stand for?

ETL expands to Extract, Transform and Load which are stage s or phases of moving data from one data source or database to another.

Q.27 What is ETL Testing?

ETL testing – ETL expands to Extract, Transform and Load hence, ETL testing involves testing the ETL procedure in all stages of ETL i.e. pre-ETL or extract stage, during Transform stage and final or load stage.

ETL testing generates test cases for checking data correctness, reliability and completeness during the ETL process.

Q.28 Is ETL Testing difficult?

ETL Testing is not difficult but complex as deeper understanding of ETL process and its phases is needed along with data representation and conversion.

ETL Testing has many challenges and the crucial being testing the data for correctness, validity, reliability and completeness, considering the variety in data representation and schema.

Q.29 Which tool is used for ETL Testing?

Many tools are used for ETL Testing. Selecting ETL tool depends upon various factors like your requirements, budget, time for testing, what to test, etc

Q.30 Is ETL testing manual testing?

ETL  testing is not manual testing as manual testing is testing of software tools and applications, manually. Test design, execution and analysis, all stages of software testing are manually. It can include software testing, out of preview of ETL Testing.

ETL Testing is implemented in all phases of ETL process i.e. Extract, Transform and Load for data correctness, validity, reliability and completeness.

ETL testing can be done manually or by using scripts for automation.

Q.31 What are the skills required for ETL Testing?

The skills required for ETL Testing are

-          Technical skills in using ETL Testing tools

-          Good database design concepts and technique knowledge

-          Conversant with SQL, SQL queries and procedures

-          Knowledge of ETL and data warehousing

-          Data quality testing experience

-          Logical for preparing scripts for automation

-          Team player to collaborate with other team members and other departments

Q.32 Does ETL Testing have scope?

Yes, ETL Testing has scope of the complete ETL process. ETL testing involves testing the ETL procedure in all stages of ETL i.e. pre-ETL or extract stage, during Transform stage and final or load stage.

ETL Testing helps testing professionals get more career related benefits. You can register for ETL Testing at link -

Q.33 How is ETL Testing done?

ETL testing is done similar to other software testing. ETL testing involves, setting test goals, making test plans and test suites and then executing test plans and analyzing the results.

ETL testing is executed at all stages of ETL - extract stage, Transform stage and load stage for data completeness, validity, reliability and correctness.

Q.34 Can we automate ETL Testing?

We can automate ETL Testing by using scripts and automation tools. Various automation tools are available as commercial and open source software.

Q.35 Can selenium be used for ETL Testing?

Selenium can be used for ETL Testing is there is a need for same. But, usually Selenium is used for automation testing of web applications.

Q.36 What is data validation in ETL Testing?

Data validation in ETL Testing refers to validating data for its data quality against prescribed level of quality being desired.

Data validation in ETL Testing ensures correctness and reliable data being transferred to new data source or database.

Q.37 What is ETL SQL?

ETL SQL  refers to usage of SQL in ETL. ETL expands to Extract, Transform and Load. ETL SQL  usage is as per database and data warehouse used for ETL implementation.

Q.38 What is data ETL?

Data ETL refers to data in the ETL process. ETL is process of moving data from one database to other whilst, transforming it as well.

Q.39 What is ETL QA?

ETL QA refers to applying QA or quality assurance for ETL process, to ensure conformance to quality levels, during ETL. QA conducts data validation and verification, to maintain data integrity and reliability.

ETL QA maintains quality across all phases of ETL - Extract, Transform and Load

Q.40 What are ETL Tester responsibilities?

ETL Tester responsibilities includes

-          Developing test cases as per requirement

-          Executing test cases

-          Analyzing test case execution results

-          Documenting all test cases and results for future

Q.41 What are ETL skills?

ETL skills include

-          Technical skills in using ETL tools

-          Learning skills for grasping new tools

-          Good database design concepts and technique knowledge

-          Conversant with SQL, SQL queries and procedures

-          Knowledge of ETL and data warehousing

-          Data quality testing experience

-          Logical mindset for automation script preparation

Q.42 Why ETL Testing is required?

ETL Testing is required for checking data correctness, reliability and completeness during the ETL process. ETL Testing assures that data has been loaded to destination database while maintaining correctness and reliability of the data.

Q.43 What is ETL architecture?

ETL architecture refers to the architecture or layout of all components in the ETL process, their role, interfaces, data exchange and quality to be maintained.

Q.44 What are the challenges faced in ETL Testing?

The challenges faced in ETL Testing are

-          Poor business information availability

-          Risk of data loss during ETL process

-          Vague requirements

-          Indifferent data representations

-          Multitude of data transformations

-          Metadata inconsistencies

Q.45 What is test data in manual testing?

Test data in manual testing refers to sample data used in execution of test cases. Test data should be carefully selected as per the goals of testing so as to better discover errors in the system. Test data in manual testing verifies and validates the software under test as per output generated by execution of test cases with test data.

Q.46 What is ELT testing?

ETL testing – ETL expands to Extract, Transform and Load hence, ETL testing involves testing the ETL procedure in all stages of ETL i.e. pre-ETL or extract stage, during Transform stage and final or load stage.

Q.47 Is there any certification for automation testing?

There is certification for automation testing and other software testing as well at link -

Q.48 Which certification is best for testing?

Certification best for testing are dependent upon your skills, testing type you want to certify upon and time you can provide for preparing and appearing for certification.

You should select testing certification by answering following questions

-          Does Hard copy or e-learning is provided?

-          Practice test for assessing oneself is given?

-          Are video demonstrations provided?

-          What is the alumni strength

Vskills provides the all the above for software testing at link -

Q.49 Is there any certification for ETL testing?

Yes, ETL testing certification is at link -


Vskills offers following deliverables

-          Online video based, e-learning LMS

-          Hard copy to candidates residing in India

-          Practice tests for assessing your knowledge

-          Government certification

-          Alumni is in software testing companies like Accenture, Cognizant, IBM, TCS, etc

Q.50 Is there any good link to practice my ETL testing skills?

Yes, link to practice ETL testing skills is at link -

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