Operational Data Store Interview Preparation Guide Download PDF
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11 Operational Data Store Questions and Answers:
1 :: Explain normalization?
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.
► Minimizing redundancy
► Minimizing insertion, deletion and update anomalies.
2 :: Explain DDL (Data Definition Language)?
A data base schema is specifies by a set of definitions expressed by a special language called DDL.
3 :: Explain Functional Dependency?
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.
4 :: What is a functional dependency F said to be minimal?
► 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.
► 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.
5 :: Explain a Relation Schema and a Relation?
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).
6 :: What is operational data store?
An operational data store (or "ODS") is a database designed to integrate data from multiple sources to make analysis and reporting easier.
7 :: What is a Relationship?
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.
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.
8 :: Tell me what is degree of a Relation?
It is the number of attribute of its relation schema.
9 :: Explain Multivalued dependency?
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)) ]
► 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)) ]
10 :: What is VDL (View Definition Language) explain?
It specifies user views and their mappings to the conceptual schema.