Operational Data Store Interview Questions & Answers

Question 1. When Is A Functional Dependency F Said To Be Minimal?

Answer :

• Every dependency in F has a single attribute for its right hand side.
• It cannot replace any dependency X -->A in F with a dependency Y--> A where Y is a proper subset of X and still have a set of dependency that is equivalent to F.
• We cannot remove any dependency from F and still have set of dependency that is equivalent to F.

Question 2. What Is Operational Data Store?

Answer :

An operational data store (or "ODS") is a database designed to integrate data from multiple sources to make analysis and reporting easier.

Question 3. What Is Multivalued Dependency?

Answer :

Multivalued dependency denoted by X-->Y specified on relation schema R, where X and Y are both subsets of R, specifies the following constraint on any relation r of R: if two tuples t1 and t2 exist in r such that t1[X] = t2[X] then t3 and t4 should also exist in r with the following properties

• t3[x] = t4[X] = t1[X] = t2[X]
• t3[Y] = t1[Y] and t4[Y] = t2[Y]
• t3[Z] = t2[Z] and t4[Z] = t1[Z]

where [Z = (R-(X U Y)) ]

Question 4. What Is Ddl (data Definition Language)?

Answer :

A data base schema is specified by a set of definitions expressed by a special language called DDL.

Question 5. What Is Vdl (view Definition Language)?

Answer :

It specifies user views and their mappings to the conceptual schema.

Question 6. What Is Degree Of A Relation?

Answer :

It is the number of attribute of its relation schema.

Question 7. What Is A Relation Schema And A Relation?

Answer :

A relation Schema denoted by R(A1, A2, ?, An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of n-values t=(v1,v2, ..., vn).

Question 8. How Does Tuple-oriented Relational Calculus Differ From Domain-oriented Relational Calculus?

Answer :

The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL

The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.

Question 9. What Is Relationship?

Answer :

It is an association among two or more entities.

Relationship Set - The collection (or set) of similar relationships.

Relationship Type - Relationship type defines a set of associations or a relationship set among a given set of entity types.

Degree of Relationship Type - It is the number of entity type participating.

Question 10. What Is Normalization?

Answer :

It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties.

• Minimizing redundancy
• Minimizing insertion, deletion and update anomalies.

Question 11. What Is Functional Dependency?

Answer :

Functional dependency is denoted by X --> Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.