data modelling interview questions

December 2, 2020

Ans: Identifying, Non-Identifying Relationship, Self-Recursive relationship are the types of relationship. Whether you’re new to the world of big data and looking to break into a Data Engineering role, or you’re an experienced Data Engineer looking for a new opportunity, preparing for an upcoming interview can be overwhelming. OLTP maintains the transactional data of the business & is highly normalized generally. Automic values:- The Single cell have only single value b) Junk Dimension: It is a dimension table comprising of attributes that don’t have a place in the fact table or in any of the current dimension tables. The approach by which conceptual data models are created is called as conceptual data modeling. Explain each of them in detail with an example? If the combination is a lot and those combination do not have any factual data then creating space to store those aggregations will be a waste as a result, the database will become huge. Q46). Transitive dependence means that descriptor key attributes depend not only on the whole primary key, but also on other descriptor key attributes that, in turn, depend on the primary key. Ans: ER diagram is a visual representation of entities and the relationships between them. Functional dependency indicates that a link exists between the values in two different columns. Ans: When group of columns are in a foreign key, it is called as composite foreign key constraint. Ans: Using a name as the primary key violates the principle of stability. Ans: Row also known as tuple or record is the horizontal alignment of the data. It can be a column or a combination of columns. It shows how the entities are linked to each other. Mindmajix offers Advanced Data Modeling Interview Questions 2020 that helps you in cracking your interview & acquire dream career as Data Modeling Architect. Q #21) What particulars you would need to come up with a conceptual model in a health care domain project? Q #9) What are the different types of dimensions you have come across? So, more than one null will be inserted in the column without any error. The star schema is quite simple, flexible and it is in de-normalized form. Give us a non-computer example of preemptive and non-preemptive scheduling? Q #1) What do you understand by Data Modelling? Ans: The visual representation of objects in a relational database (usually a normalized) is called as relational data modeling. For Example, the net amount due is a fact. is a non-additive measure. On the contrary, star schema has a high level of redundancy and thus it is difficult to maintain. Surrogate key is a substitute for natural keys. Data modelling is the process of creating a model for the data to store in a database. Ans: Unique constraint is imposed on the column data to avoid duplicate values, but it will contain NULL values. Answer : Enterprise data model comprises of all entities required by an enterprise. Primary Key=Unique + Not Null. Let's have a look into them. For Example, if the subscriber dimension is connected to two fact tables – billing and claim then the subscriber dimension would be treated as a conformed dimension. We fulfill your skill based career aspirations and needs with wide range of How do you resolve them? Q #24) What is the significance of metadata? Q38). They also set the stage for the design of databases later on in the SDLC.There are three basic elements in ER models:Entities are the “things” about which we seek information.Attributes are the data we collect about the entities.Relationships provide the structure needed to draw information from multiple entities. If yes, how did you handle it? Q39). After all, we know that the relationship to the PK is good, because we established that in 2NF. Ans: In normal practice, a numerical attribute is enforced a primary key which is called as surrogate key. Answer: Metadata is data about data. Q9). And since both are vehicles, so their super-type entity is ‘vehicle’. If you're looking for Data Modeling Interview Questions for Experienced or Freshers, you are at right place. Ans: Enterprise data model comprises of all entities required by an enterprise. Conceptual, physical or external? And these dimension tables are linked by primary, foreign key relation. Q42). For Example, if you need to find out that “how many subscribers are tied to a particular plan which is currently active?” – go with the snowflake model. The approach by which physical data models are created is called as physical data modeling. These entities were subscriber, member, healthcare provider, claim, bill, enrollment, group, eligibility, plan/product, commission, capitation, etc. For Example, it can be a member eligibility flag set as ‘Y’ or ‘N’ or any other indicator set as true/false, any specific comments, etc. COM design of databases later on in the SDLC. For Example, a ratio or a percentage column; a flag or an indicator column present in fact table holding values like Y/N, etc. Very simple technical questions. Ans: Data models are tools used in analysis to describe the data requirements and assumptions in the system from a top-down perspective. Question3: What is a logical data model and logical data modeling? e) Degenerated Dimension: A degenerated dimension is a dimension that is not a fact but presents in the fact table as a primary key. So, we combine all such attributes and put in a single dimension table called a junk dimension having unique junk IDs with a possible combination of all the indicator values. Data now resides in main-memory (RAM) and no longer on a hard disk. Data Analyst Interview Questions : In my previous articles I have given the different kind of SQL interview questions with answers. Logical Data Models contain Entity, Attributes, Super Type, Sub Type, Primary Key, Alternate Key, Inversion Key Entry, Rule, Relationship, Definition etc. Statistics Interview Questions. For Example, all bikes are two-wheelers and all cars are four-wheelers. On the contrary, OLAP is for analysis and reporting purposes & it is in de-normalized form. Every interview is different and the scope of a job is different too. Q26). Answer: Facts represent quantitative data. Whether you're a candidate or interviewer, these interview questions will help prepare you for your next Data Modeling interview ahead of time. For example, a one-to-many recursive relationship occurs when an employee is the manager of other employeess. Physical Data Modeling Interview Questions and Answers. This could be defined as a substitute for natural keys. customizable courses, self paced videos, on-the-job support, and job assistance. If the purpose of your project is to do more of a metrics analysis, you should go with a star schema. Ans: Index is imposed on a column or set of columns for fastest retrieval of data. off original price! Ans: Column also known as field is a vertical alignment of the data and contains related information to that column. The approach by which data models are constructed for transactions is called as OLTP data modeling. The approach by which conceptual data models are created is called as conceptual data modeling. This is the actual implementation and extension of a conceptual data model. Data Modeling Interview Questions Enroll in Course for $27. Here are data modelling interview questions for fresher as well as experienced candidates. If the referenced column in the child table is a part of the primary key in the child table, relationship is drawn by thick lines by connecting these two tables, which is called as identifying relationship. c) Role-Playing Dimension: These are the dimensions that are utilized for multiple purposes in the same database. Ans: Data sparsity is term used for how much data we have for a particular dimension/entity of the model.It affects aggregation depending on how deep the combination of members of the sparse dimension make up. Q #10) Give your idea regarding factless fact? Data modeling is a diagrammatic representation. Most Frequently Asked Data Modeling Interview Questions. Answer: There are three types of data models – conceptual, logical and physical. Ans: Consider any system where people use some kind of resources and compete for them. Answer: Few common mistakes encountered during Data Modelling are: Q #18) What is the number of child tables that can be created out from a single parent table? This is a case where a derived, rather than a natural, primary key is appropriate. SQL and Data modeling related. Ans: An entity can be split into many entities (sub-entities) and grouped based on some characteristics and each sub entity will have attributes relevant to that entity. The level of complexity and detail increases from conceptual to logical to a physical data model. Still, we can pinpoint Top 20 financial modeling interview questions (with answers), which will help you leap from being a potential employee to a new one. Given how competitive this market is right now, you better be prepared for your interview. Explain with example. Here, a vehicle is a super-type entity. The example for preemptive scheduling is people standing in queue for tickets. What are the important types of Relationships in a data model. We make learning - easy, affordable, and value generating. The foreign key column value in the child table will always refer to primary key values in the parent table. Unlike a primary key, it is not picked up from the existing application data fields. Ans: The conceptual data model includes all major entities and relationships and does not contain much detailed level of information about attributes and is often used in the initial planning phase. Ans: When more than one column is a part of the primary key, it is called as composite primary key constraint. Data Modeling Interview Questions We already have a database structure, but it is the structure without normalization and very confused and in need of change, but already has a large volume of stored data, for example, all financial data company, which finance department officials are afraid of losing. Data Ware house and Data Mart Interview Questions and Answers. What is ER (entity relationship) diagram or ERD? What is a composite foreign key constraint? Now, I will be explaining each of these schemas one by one. Non-additive measures are the ones on top of which no aggregation function can be applied. Question5: What is the difference between a logical and physical data model? Q #11) Distinguish between OLTP and OLAP? Data Modeling Tools have options to create reports by checking various options. For Example, units purchased. What is the difference between a logical and physical data model? Q4). The social security number might be a valid choice, but a foreign employee might not have a social security number. Generally, the data models are created in data analysis & design phase of software development life cycle. In a snowflake schema, the level of normalization increases. Answer: This is the scenario of an external level of data hiding. Had 6 rounds. Helping our community since 2006! Because, if the doctor himself falls ill and needs surgery, he will have to visit some other doctor for getting the surgical treatment. Snow Flake: Its almost like starschema but in this our dimension tables are in 3rd NF, so more dimensions tables. Question4: What is a physical data model and physical data modeling? We can also call it as a single attribute dimension table. Q #19) Employee health details are hidden from his employer by the health care provider. Download & Edit, Get Noticed by Top Employers! You will absolutely love our tutorials on QA Testing, Development, … This helps to quickly retrieve the information from the database. It combines row-based, column-based database technology. Ans: Usually, in a data model, parent tables and child tables are present. What is data modeling? The important or main object in a database is a table which consists or rows and columns. What is a logical data model and logical data modeling? What is forward engineering in a data model? Q #2) Explain your understanding of different data models? ( 80% asked Data Modeling Interview Questions ) Answer : The first normal form is the normal form of database where data must not contain repeating groups.The database is in First normal form If, 1.It contains only automic values. We had a data warehouse that was holding the information pertaining to all these departments and then we have few data marts built on top of this data warehouse. I would suggest that whenever you are answering a question to the interviewer, it’s better that you explain the idea through an example. Ans: Check constraint is used to check range of values in a column. Ans: Many null values can be inserted in an unique constraint column because one null value is not equal to another null value. Erwin Data Modeling Tool Interview Questions and Answers. Top 30 SAS Interview Questions and Answers. A logical data modeler  designs the data model to suit business requirements, creates and maintains the lookup data, compares the versions of data model, maintains change log, generate reports from data  model and whereas a physical data modeler has to know about the source and target databases properties.A physical data modeler should know the technical-know-how  to create data models from existing databases and to tune the data models with referential integrity, alternate keys, indexes and how to match indexes to SQL code. Q24). Mindmajix - The global online platform and corporate training company offers its services through the best Different categories of health care plans and products. The following explanations make this more specific: If the table has a one-column primary key, the attribute must depend on that key.If the table has a composite primary key, the attribute must depend on the values in all its columns taken as a whole, not on one or some of them. The attributes which are common to these entities are moved to a super (higher) level entity, which is called as supertype entity. What is a composite primary key constraint? Instead of having primary key or composite primary keys, the data modelers create a surrogate key; this is very useful for creating SQL queries, uniquely identify a record and good performance. When should you consider denormalization? It has only the dimension keys in it. Due to several layers of dimension tables, it looks like a snowflake and thus it is named as snowflake schema. The facets database in my project was created with SQL server 2012. Ans: A data model is a conceptual representation of business requirement (logical data model) or database objects (physical) required for a database and are very powerful in expressing and communicating the business requirements and database objects. Q #3) Throw some light on your experience in Data Modelling with respect to projects you have worked on till date? In relational terms, every column in a table must be functionally dependent on the whole primary key of that table. all databases must be in third normal form? Answer: Data Modelling is the diagrammatic representation showing how the entities are related to each other. This difference between OLAP and OLTP also gives you the way to choosing the design of schema. It is the initial step towards database design. Ans: Usually, in a data model, parent tables and child tables are present. Deep Learning Interview Questions. 250+ Data Modeling Interview Questions and Answers, Question1: What is data modeling? Machine Learning Interview Questions. Data Modeling Interview Questions And Answers Global Guideline . What is a logical data model and logical data modeling? What are the types of normalization? The employee entity is related to itself, and there is a one-to-many relationship between one employee (the manager) and many other employees (the people who report to the manager). Answer: A recursive relationship occurs in the case where an entity is related to itself. What is a physical data model and physical data modeling? Answer: The number of child tables that can be created out of the single parent table is equal to the number of fields/columns in the parent table that are non-keys. So if you have finally found your dream job in Data Modeling but are wondering how to crack the 2020 Data Modeling Interview and what could be the probable Data Modeling Interview Questions. Below is the conceptual Data Model showing how the project looked like on a high-level. Interview Questions for Data Modeling.How prolonged do you plan to stay at company if offered the Data Modeling position?What was the most … Data Modeling Interview Questions for Freshers & Experienced Q1). A natural key is one that is already part of the database. The coupon code you entered is expired or invalid, but the course is still available! I did the Bar raiser round well too. If the attribute also depends on other columns, they must be columns of a candidate key; that is, columns that are unique in every row. Each of the data entities has its own data attributes. Since star schema is in de-normalized form, you require fewer joins for a query. Now, which one to choose for your project? For Example, if you need to find out that “what is the claim amount paid to a particular subscriber?” – go with a star schema. At times, certain situations may arise in the business where you need to have a factless fact table. It is the initial step towards database design. For Example, plan, product, class are all dimensions. Q16). I think all this added focus on data has given us a ripe opportunity to help our business organizations to leverage data modeling and other data management approaches even more than ever. Either you can create a logical data model Metadata of physical model Metadata. A super-type entity is the one that is at a higher level. When should it be used? Q35). But there is more you can do to help weigh the odds in your favor. Answer: It is not mandatory for a database to be in 3NF. Ans: A standalone column in a table will be connected to the primary key of the same table, which is called as recursive relationship. If your system is OLTP, you should go with star schema design and if your system is OLAP, you should go with snowflake schema. With these scripts, databases can be created. Semi- additive measures are the ones on top of which some (but not all) aggregation functions can be applied. Join our subscribers list to get the latest news, updates and special offers delivered directly in your inbox. Car and bike are its sub-type entities. Is this statement TRUE or FALSE? Q15). Copyright © 2020 Mindmajix Technologies Inc. All Rights Reserved. For Example, I used to work for a health insurance provider company that had different departments in it like Finance, Reporting, Sales and so forth. Talking about the health care domain, it is a possibility that a health care provider (say, a doctor) is a patient to any other health care provider. Top 24 Data Modeling Interview Questions with Detailed Answers. Q18). You can see that the above table does not contain any measure. Example: social security number, bank account number, bank routing number. Ans: Sequence is a database object to generate a unique number. An example of the fact table can be seen from Figure 2 shown above. Q #1) What do you understand by Data Modelling? For Example, a data attribute of the provider will be provider identification number, few data attributes of the membership will be subscriber ID, member ID, one of the data attribute of claim will claim ID, each healthcare product or plan will be having a unique product ID and so on. The ER diagram (see Figure 2) of this schema resembles the shape of a star and that is why this schema is named as a star schema. Below are the varies types of SCDs. Keeping this in mind we have designed the most common Data Modeling Interview Questions and answers to help you get success in your interview. Instead of generating primary or foreign keys, surrogate keys are generated by the database and they are further helpful in designing the SQL queries. Explore Data Modeling Sample Resumes! Q #22) Tricky one:  If a unique constraint is applied to a column then will it throw an error if you try to insert two nulls into it? 30+ TOP Data Modelling Interview Questions and Answers Data Modelling Interview Questions. A recursive relationship occurs when there is a relationship between an entity and itself. Top 50+ Database Interview Questions and Answers. Q #6) Which schema is better – star or snowflake? What is the difference between star flake and snow flake schema? 2) Explain various types of data models. Sadly, I was told the position was for Data engineer-3 and that I was suitable only for Data Engineer-2 but also that I had to wait for a year and give the interview again. Ans: Data Model and its relevant data like entity definition, attribute definition, columns, data types etc. List of Most Frequently Asked Data Modeling Interview Questions And Answers to Help You Prepare For The Upcoming Interview: Here I am going to share some Data Modeling interview questions and detailed answers based on my own experience during interview interactions in a few renowned IT MNCs. Most popular portal for Software professionals with 100 million+ visits and 300,000+ followers! A data base can also be created without normalization. There are three basic elements in ER models: Entities are the "things" about which we seek information. Which level of data hiding is this? So, the factless fact table offers flexibility to the design. Ans: Forward Engineering is a process by which DDL scripts are generated from the data model. If the referenced column in the child table is a not a part of the primary key and standalone column in the child table, relationship is drawn by dotted lines by connecting these two tables, which is called as non-identifying relationship. Ans: Parent table has primary key and a foreign key constraint is imposed on a column in the child table. How many null values can be inserted in a column that has a unique constraint? Sub-type entities are ones that are grouped together on the basis of certain characteristics. Database performance, indexing strategy, and physical storage are important parameters of a physical model. Hence it is not a mandatory that a database should be in 3nf. 1) What is data modelling? For Example, suppose you are maintaining an employee attendance record system, you can have a factless fact table having three keys. When a numerical attribute is enforced on a primary key in a table, it is called the surrogate key. ; These Data Modeling Interview Questions are useful for Beginners as well as Experienced Data Modeling Professionals. Data modeling Interview Questions and Answers will guide us now that Data modeling in software engineering is the process of creating a data model by applying formal data model descriptions using data modeling techniques. Ans: One to One, One to many, and many to many are different types of cardinalities. If you do not convert your model to the second normal form, you risk data redundancy and difficulty in changing data. SAP HANA is an in-memory database: It is a combination of hardware and software made to process massive real time data using In-Memory computing. Every interview is different and the scope of a job is different too. Why are recursive relationships are bad? Data Modeling Interview Question 1.What do you understand by data modeling? To convert first-normal-form tables to second-normal-form tables, remove columns that are not dependent on the primary key. The conceptual model shows a very basic high level of design while the physical data model shows a very detailed view of design. Data Modeling Interview Questions “Data Modeling Interview Questions” are useful for preparing “Data Modeler / Data Architect ” Interviews. Introduction To Data Modeling Interview Questions And Answers. Tell us something about the surrogate key. What is the difference between a logical and physical data model? Q5). In simpler words, it is a rational or consistent design technique used to build a data warehouse. What is non-identifying relationship? In fact, interviewers will also challenge you with brainteasers, behavioral, and situational questions. Question 21. What is a subtype and supertype entity? Q #15) Is this true that all databases should be in 3NF? Employers use data modeling interview questions … Each column has datatype and based on the situation, integrity constraints are enforced on columns. In organization the user needs to play different roles like database admin,data analyst,data developer.In this article i will try to give different SQL Interview Questions with answers for Data … Data Modeling Interview Questions: In the blog, you have to learn the list of frequently asked Data Modeling interview questions and answers for freshers and experienced professionals. a) Conformed dimensions: A Dimension that is utilized as a part of different areas are called a conformed dimension. So, in this case, the entity – health care provider is related to itself. A derived key is an artificial key that you create. The data about various objects in the data model is called as data model Metadata. Ans: Recursive relationships are an interesting and more complex concept than the relationships you have seen in the previous chapters, such as a one-to-one, one-to-many, and many-to-many. Denormalization is done in dimensional data modelling used to construct a data ware house. It tells you what kind of data is actually stored in the system, what is its purpose and for whom it is intended. In star schema dimensional tables are usually not in BCNF form. Q36). A fact table contains numerical data and foreign keys from related dimensional tables. Give us a non-computer example of preemptive and non-preemptive scheduling? Answer: Yes, let’s say we have these different entities – vehicle, car, bike, economy car, family car, sports car. Ans: Constraint is a rule imposed on the data. The non-computer examples for preemptive scheduling the traffic on the single lane road if there is emergency or there is an ambulance on the road the other vehicles give path to the vehicles that are in need. Let’s start! Answer: There are typically five types of dimensions. In a data model, entities (tables) look like square boxes or rectangular boxes, which contain attributes and these entities, are connected by lines (relationship). About us | Contact us | Advertise | Testing Services All articles are copyrighted and can not be reproduced without permission. DATA MODELING Interview Questions and Answers :- 1. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. In a database, high cardinality means more unique values are stored in a column and vice versa. It might be utilized with different fact tables in a single database or over numerous data marts/warehouses. And why do we use it? For Example, a date dimension can be used for “Date of Claim”, “Billing date” or “Plan Term date”. What is self-recursive relationship? Q20). If the purpose of your project is to do more of dimension analysis, you should go for snowflake schema. Yes, I have come across such a scenario. Ans: An entity is in the second normal form if all of its attributes depend on the whole (primary) key. You are here: Home / Latest Articles / Data Analytics & Business Intelligence / Top 30 Data Analyst Interview Questions & Answers last updated October 3, 2020 / 3 Comments / in Data Analytics & Business Intelligence / by renish Ans: You can take a report of the entire data model, or subject or part of the data model. The primary key in all dimension tables acts as a foreign key in the fact table. © Copyright SoftwareTestingHelp 2020 — Read our Copyright Policy | Privacy Policy | Terms | Cookie Policy | Affiliate Disclaimer | Link to Us, Q #4) What are the different design schemas in Data Modelling? We first create the conceptual model, then the logical model and finally move to the physical model. Ans: A data model is a conceptual representation of business requirement (logical data model) or database objects (physical) required for a database and are very powerful in expressing and communicating the business requirements and database objects. Q #12) What do you understand by data mart? They are designed for the individual departments. In addition to emphasizing your skills in data modeling, these interview questions also seek to extract your experience with data modeling tools, principles and resources. Question 7 : What is first normal form ? Data modeling interview questions are those designed for candidates to display introductory to expert level knowledge of data modeling principles and practices. if we keep all such indicator attributes in the fact table then its size gets increased. Furthermore, economy cars, sports cars, and family cars are sub-type entities of its super-type entity- car. There are a lot of opportunities from many reputed companies in the world. What is data sparsity and how it effect on aggregation? Q #16) Have you ever came across the scenario of recursive relationships? Attributes are the data we collect about the entities. Answer: Data marts are for the most part intended for a solitary branch of business. Ans: The primary key constraint is imposed on the column data to avoid null values and duplicate values. For 3NF, first, the table must be in 2NF, plus, we want to make sure that the non-key fields are dependent upon ONLY the PK, and not other non-key fields for its existence. Heck, data management even made it into the US State of the Union Address. Answer: No, it will not throw any error in this case because a null value is unequal to another null value. Because of the more complex nature of these relationships, we will need slightly more complex methods of mapping them to a schema and displaying them in a style sheet. What is data modeling? It does not have its own dimension table. Ans: First normal form, Second normal form, third normal forms are three types of normalization used in practice. If you want to become a Certified Data Modeling Specialist, then visit Mindmajix - A Global online training platform: This course will help you to achieve excellence in this domain. Generally, these are properties like flags or indicators. Ans: Data stored in form of rows and columns is called as table. Q3). d) Slowly Changing Dimension (SCD): These are most important amongst all the dimensions. According to research Dimensional Data Modeling has a market share of about 15%. Data modeling tools have options to connect to the database by which we can reverse engineer a database into a data model. Advanced-Data Modeling Interview Questions. You are here: Home / Latest Articles / Data Analytics & Business Intelligence / Top 50 Data Warehouse Interview Questions & Answers last updated October 3, 2020 / 4 Comments / in Data Analytics & Business Intelligence / by admin Since it does not have its own dimension table, it can never act as a foreign key in the fact table. In my project, we used snowflake schema because we had to do analysis across several dimensions and generate summary reports for the business. Frequently Asked Data Modeling Interview Questions - [Updated 2020]. 1. Answer: Dimensions represent qualitative data. Answer: (Combined for Q #5&6): The choice of a schema always depends upon the project requirements & scenarios. So, such a dimension will be called a Role-playing dimension. For better understanding purpose, these data models are split up into subject areas. Another significant difference between these two schemas is that snowflake schema does not contain redundant data and thus it is easy to maintain. Q #13) What are the different types of measures? This course will help you to achieve excellence in this domain. If you're looking for Dimensional Data Modeling Interview Questions & Answers for Experienced or Freshers, you are at right place. Logical | Physical Data Modeling:Ans: When a data modeler works with the client, his title may be a logical data modeler or a physical data modeler or combination of both. The development of a common consistent view and understanding of data elements and their relationships across the enterprise is referred to as Enterprise Data Modeling. We had different entities that were linked together. Answer: For a health care project, below details would suffice the requirement to design a basic conceptual model. Dimensional Data Modeling Interview Questions and Answers. What is an artificial (derived) primary key? Ans) Dimensional modeling is often used in Data warehousing. Ans: OLTP acronym stands for ONLINE TRANSACTIONAL PROCESSING. Q40). A data model is a conceptual representation of business requirement (logical data model) or database objects (physical) required for a database and are very powerful in expressing and communicating the business requirements and database objects. This is not usually done for data bases of transactional systems. Data Analysis Interview Questions. Top 24 Data Modeling Interview Question and Answers You Need to Prepare For Your Interview By SimplilearnLast updated on Jan 24, 2020 10308. What is a constraint? Answer: Factless fact table is a fact table that contains no fact measure in it. So learn data modeling by this Data modeling Interview Questions with Answers guide . You can stay up to date on all these technologies by following him on LinkedIn and Twitter. Data modeling tools have options to create DDL scripts by connecting with various databases. Ravindra Savaram is a Content Lead at Mindmajix.com. Q #20) What is the form of fact table & dimension table? What is reverse engineering in a data model? Below question-answers can be of your great help if you get a chance to face or take an interview on Data Modelling. According to research Data Modeling has a market share of about 15.43%. It  would be good if the physical data modeler knows about replication, clustering and so on. A dimension table contains descriptive or textual attributes. Explain with the example? Be well prepared for scenario based questions as well. This is very similar to to 2NF, except that now you are comparing the non-key fields to OTHER non-key fields. Example: all online transactions, bank transactions, trading transactions. If the value of an attribute depends on a column, the value of the attribute must change if the value in the column changes. But, instead of keeping it separately in a dimension table and putting an additional join, we put this attribute in the fact table directly as a key. What is the difference between hashed file stage and sequential file stage in relates to DataStage Server? Data Modelers create conceptual data model and forward that model to functional team for their review. Ans: Denormalization is used when there are a lot of tables involved in retrieving data. How is it different from a primary key? Interview questions for SAP-HANA Data Modelling General Questions: 1.What is SAP-HANA?. Q11). Answer: OLTP stands for the Online Transaction Processing System & OLAP stands for the Online Analytical Processing System. Coming to the snowflake schema, since it is in normalized form, it will require a number of joins as compared to a star schema, the query will be complex and execution will be slower than star schema. Q14). Q47). So, before you step into the interview discussion, you should have a very clear picture of how data modeling fits into the assignments you have worked upon. We first create the conceptual model, then the logical model and finally move to the physical model. So, how do you prepare for a successful data architect interview? These DataMart were specific to each department. Ans: Physical data model includes all required tables, columns, relationship, database properties for the physical implementation of databases. Q #23) Can you quote an example of a sub-type and super-type entity? Ans: Logical Data Model: Entity, Attributes, Super Type, Sub Type, Primary Key, Alternate Key, Inversion Key Entry, Rule, Relationship, Definition, business rule, etcPhysical Data Model: Table, Column, Primary key Constraint, Unique Constraint or Unique Index, Non Unique Index, Check Constraint, Default Value, Foreign Key, comment etc. The simplest of the schemas is star schema where we have a fact table in the center that references multiple dimension tables around it. The different types of constraints are primary key, unique, not null, foreign key, composite foreign key, check constraint etc. Ans: Reverse Engineering is a process useful for creating the data models from database or scripts. Data modeling interview questions are those designed for candidates to display introductory to expert level knowledge of data modeling principles and practices. Parent table and child table are connected by a relationship line. This field has a lot for the potential seekers and the individuals interested in the visualization in software engineering. Oracle Database Fundamentals Interview Questions and Answers . These are the dimensions where attribute values vary with time.

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