data warehouse testing interview questions

It deletes junk data's like rows with null values or extra spaces. Data staging is an area where you hold the data temporary on data warehouse server. 14) Using SSIS ( SQL Server Integration Service) what are the possible ways to update table? So, the basic testing questions will also remain same. 11) Explain the use of Lookup Transformation? Data warehouses also help to integrate data from different sources and show a single-point-of-truth values about the business measures (e.g. SUM(), AVG() etc.). ETL testing interview questions and answers ETL testing is a popular trend today with plenty of job opportunities and attractive salary options. Data warehousing is a system which is used for reporting purpose as well as data analysis purpose where data is coming from multiple heterogeneous sources whether it is  oracle, sql server, postgres,simple excel sheet.Data warehousing is specially used for reporting historical data.Data warehousing is core component of Business Intelligence.In Data warehouse there is one central mechanism called as repository using which one can fetch the historical reports.In Data warehouse user can store current data as well as historical data on single place called as repository.Data warehouse provides generalized data and consolidated data in multidimensional view.Data warehouse provides Online Analytical tools to analyse the data and reporting purpose. Schema objects includes tables, views, sequence synonyms, indexes, clusters, functions packages and database links. ETL Testing Interview Questions. (100 % asked Data warehouse Interview Questions ). Snowflake schema is a form of dimensional modeling where dimensions are stored with multiple dimension tables.Snowflake schema is variation over star schema.The schema is diagrammed as each fact is surrounded with dimensions;and some dimensions are further related to other dimensions which are branched in snowflake pattern.In snowflake schema multiple dimension tables are organized and joined with fact table.Only difference between star and snowflake schema is dimensions are normalized in snowflake schema.Normalization splits up data in to additional tables. The types of data warehouse applications are, Data mining can be define as the process of extracting hidden predictive information from large databases and interpret the data while data warehousing may make use of a data mine for analytical processing of the data in a faster way. Explain it. 6) Explain what are Cubes and OLAP Cubes? Data warehousing requires data cleaning,data validation and data consolidation. Thorough data warehouse interview questions seek to confirm your technical knowledge of data systems, your understanding of the role data plays in achieving business insights and your ability to convey them in a meaningful way. The data come in to Data Mart by different transactional systems,other data warehouse or external sources. ITEM KEY will be present in Fact table. Data Warehouse Interview Questions. In other words, a data warehouse contains a wide variety of data that supports the decision-making process in an organization. A sum() function on balance does not give a useful result but max() or min() balance might be useful. Today we often call this whole process of reporting data from data warehouses as “Data Analytics”. In case if you have non-OLEBD source for the lookup then you have to use Cache to load data and use it as source. A list of frequently asked ETL Testing Interview Questions and Answers are given below. Data Warehousing - 3842 Data Warehousing interview questions and 10294 answers by expert members with experience in Data Warehousing subject. Question 10 :What are different characteristics of Data Warehouse? There are three basics steps in Data Integration Process. Info Processing; Analytical Processing; Data Mining; Data mining can be define as the process of extracting hidden predictive information from large databases and interpret the data while data warehousing may make use of a data mine for analytical processing of the data in … It provides multi-dimensional analysis. Schema is logical description of whole database.Database schema is a skeleton or structure of the database which represents database logically.Same like a database Data warehouse also requires to maintain database schema.Data warehouse schema includes name of database objects with its relationship maintained in diagrammatic format.Database uses relational model where data warehouse uses following types of Database Schema: 3.Fact Constellation schema which is also called as Galaxy Schema. e.g. Example, 5% profit margin, revenue to asset ratio etc. Data Warehousing Interview Questions and Answers for Experienced. enabling Master Data Management). Less than 10% is usually verified and reporting is manual. 9) Explain what factless fact schema is and what is Measures? 1. Additive measures can be used with any aggregation function like Sum(), Avg() etc. It comes with a conformed dimensions along with a standardized definition of information. | OCA-4, What is where clause in SQL with real life examples? The goal of Dimensional model is not to achieve high degree of normalization but to facilitate easy and faster data retrieval. 2) Explain what are the ETL testing operations includes? It is usually done to free-up the database space. It is an integral part of any effective business intelligence initiative. Last updated on October 2nd, 2020 at 03:43 pm. With data … You will able to see there are four dimesions : Aggregate table contains aggregated data which can be calculated by using different aggregated functions like count,avg,min,max.e.t.c.Aggregated tables are most widely used tables in OLAP database.Aggregates are functions where the values of table or column are grouped together and form a single value. Part 1 – Data warehouse Interview Questions … The difference between ETL and OLAP tool is that. It is an essential concept in Data Warehousing systems. Data warehouse helps higher management  to take stratagic as well as tactical decisions using historical or current data. As Company head wants daily report of in-out time we need to provide it using OLTP system.We need to schedule report on daily basis using OLTP system. What is a data warehouse? Dashboards are nothing but the arrangement of all the reports and charts graphs on one page.It is nothing but the collection of reports of different formats which has same functionality displayed on the same page. 21) Mention what is the difference between Power Mart and Power Center? Data Warehouse Testing is a testing method in which the data inside a data warehouse is tested for integrity, reliability, accuracy and consistency in order to comply with the company's data framework. 14.What is snowflakes schema? There are lot of opportunities from many reputed companies in the world. Data warehouse can be further used for data mining which helps trend prediction, forecasts, pattern recognition etc. over a given time frame and use the result of our analysis to improve the efficiency of business processes. According to research ETL Testing … 10.What is mean by Fact Tables?Explain with example. (100% asked ETL Testing Interview Questions) Answer : Data warehouse is a database which is separate from operational database which stores historical information also. Following 2 points are important in defining granularity : 1.Determining the dimensions that are to be included. These are the top Data Warehousing interview questions and answers that can help you crack your Data Warehousing job interview. The fact table contains the foreign keys,time dimensions,product dimension,customer dimension,measurement values.Following are some examples of common facts : No of unit sold,Margin,Sales revenue and the dimension tables are customer,time and product e.t.c. For more info please access vi's website. The term Data Warehouse provides the user with the data and tool to answer the questions which are important to run the business or part of business.In short,the Data warehouse is used for reporting the specified data of any business which is very important and using which  the higher management of the business will take the decisions for growth of business.Now a days Business Intelligence is demanding technology to analyse the business and its history.In this article i will try to explain 20 Most important Data warehouse Interview Questions.I have explained about SQL interview questions in other articles.These questions are helpful to BI developers as well as Data warehouse people to crack the Data warehouse interviews: 1.What is OLAP(Online Analytical Processing)? Data Warehouse is more than just a database. It is also known as Fact Granularity. Data warehouse is used for reporting and data analysis purpose. Between Informatica and SAP Powerconnect act as a gateaway. Q21). OLAP stands for Online Analytics Processing, and OLAP cube stores large data in muti-dimensional form for reporting purposes. Some companies go as far as hiring people without … Reporting tools are software that provides reporting, decision making, and business intelligence... What is OLAP? Data warehouse database contains transactional as well as analytical data. A data warehouse is often built to enable Data Analytics. To update table using SSIS the possible ways are: 15) In case you have non-OLEDB (Object Linking and Embedding Database) source for the lookup what would you do? 16) In what case do you use dynamic cache and static cache in connected and unconnected transformations? In data warehousing architecture, ETL is an important component, which manages the data for any business process. A data warehouse is the electronic storage of an organization’s historical data for the purpose of data analytics. If you have attended DWBI interviews in the recent past, we encourage you to paste additional questions in the comments tab. To improve performance, transactions are sub divided, this is called as Partitioning. Normal level explains the tracing level in a detailed manner while verbose explains the tracing levels at each and every row. The next step is to generate the ABAP code for the mapping then only informatica can pull data from SAP, To connect and import sources from external systems Power Connect is used. 1) What is ETL? In the image i have explained which are fact and which are dimension tables. Datawarehouse consists of wide variety of data that has high level of business … A non-numerical data can also be a non-additive measure when that data is stored in fact tables, e.g. A data warehouse is a place where whole data is stored for analysis, OLAP is used for data analysis, aggregations, summation, and information planning at the minor level. Data Mart is a simplest set of Data warehouse which is used to focus on single functional area of the business.We can say Data Mart is a subset of Data warehouse which is oriented to specific line of business or specific functional area of business such as marketing,finance,sales e.t.c. 5) What is fact? Cubes are data processing units comprised of fact tables and dimensions from the data warehouse. It consists of facts called as measures categorized by dimensions. Answer : A data warehouse can be thought of as a three-tier system in which a middle system provides usable data in a secure way to end users. If you're looking for ETL Testing Interview Questions & Answers for Experienced or Freshers, you are at right place. 20) How you can extract SAP data using Informatica? Tracing level can be classified in two Normal and Verbose. Let’s say account balance. which is used to analyse data. The #1 Method to compare data from sources and target data warehouse – Sampling, also known as “ Stare and Compare” — is an attempt to verify data dumped into Excel spreadsheets by viewing or “ eyeballing” the data. It has no specification to convert local into global repository, Source data extraction and data transformation ( restructuring ), Data transformation (data cleansing, value transformation ), Mapplet : It arranges or creates sets of transformation, Worklet: It represents a specific set of tasks given, Workflow: It's a set of instructions that tell the server how to execute tasks, Session: It is a set of parameters that tells the server how to move data from sources to target. 15.What is mean by Granularity? Rather than directly from data source objects, dimensions and cubes are created from data source views. There are lot of opportunities from many reputed companies in the world. If you're looking for Data Warehouse Interview Questions & Answers for Experienced or Freshers, you are at right place. Ralph Kimball is one of the strongest proponents of this very popular data modeling technique which is often used in many enterprise level data warehouses. A list of frequently asked Data Warehouse Interview Questions and Answers are given below.. 1) What is a data warehouse? Fact tables store different transactional measurements and the foreign keys from dimension tables that qualifies the data. ETL tool is meant for the extraction of data from the legacy systems and load into specified data base with some process of cleansing data. Answers are given below warehouse Analyst Interview Question or answer values about business. Parallel processing of high-volume intelligence AG ) to personalize content and advertising comes with conformed. Common repository warehouse can be defined as the data for any business process to identify the common dimensions, schema... 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