Principles of Data Management Exam 1 Questions With Correct Answers
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Principles of Data Management
Institution
Principles Of Data Management
Principles of Data Management Exam 1 Questions With Correct Answers
.Advantages of DB Systems and DB Management - ANSWER-- data independence
- DB modelling
- managing structured, semi-structured, and unstructured data
- managing data redundancy
- specifying integrity rules
- concurrency con...
Principles of Data Management Exam 1
Questions With Correct Answers
.Advantages of DB Systems and DB Management - ANSWER-- data independence
- DB modelling
- managing structured, semi-structured, and unstructured data
- managing data redundancy
- specifying integrity rules
- concurrency control
- backup and recovery facilities
- data security
- performance utilities
.Aggregation - ANSWER-- entity types that are related by a particular relationship type can be combined
or aggregated into a higher-level aggregate entity type
- aggregation is especially useful when the aggregate entity type has its own attribute types and/or
relationship types
.Architecture of a DBMS - ANSWER-- Connection Manager
- Security Manager
- DDL Compiler
- Query Processor
- Storage Manager
- DBMS Utilities
- DBMS Interfaces
.Attribute Types - ANSWER-- Attribute types represents a property of an entity type
ex) name and address are attribute types of the entity type supplier
,- Attribute is an instance of an attribute type
.Backup and Recovery Facilities - ANSWER-- used to deal with the effects of loss of data due to hardware
or network errors, bugs, etc.
- backup facilities can either perform a full or incremental backup
- recovery facilities allow to restore the data to the previous state after loss of data occurred
- DB does this for you (files typically don't)
.Basic Concepts of a Relational Model - ANSWER-- A database is a collection of relations
- A relation is a set of tuples, representing real world things
- Tuples are an ordered list of attributes that describe an entity
.Boyce-Codd Normal Form (BCNF) - ANSWER-- a functional dependency X -> Y is called a trivial functional
dependency if Y is a subset of X
- a relation R is in the Boyce-Codd normal form (BCNF) provided each of its non-trivial functional
dependencies X -> Y, X is a superkey (X is either a candidate key or a superset thereof)
- BCNF normal form is stricter than 3NF (every relation in BCNF is also in 3NF [not vice versa])
.Buffer Manager - ANSWER-- manages buffer memory of the DBMS
- intelligently caches data in the buffer
ex) Data locality: data recently retrieved is likely to be retrieved again
ex) 20/80 law: 80% of transactions read or write only 20% of the data
- Must adopt smart replacement strategy in case buffer is full
- needs to interact with lock manager
.Candidate Key - ANSWER-- a relation scheme R is a superkey of R with the additional property that
removing any attribute type from K leaves a set of attribute types that is no superkey of R
- does not have any redundant attribute types (minimal superkey)
- every relation must have at least 1 key that allows to uniquely identify its tuples
, .Cardinalities - ANSWER-- every relationship type can be characterized in terms of its cardinalities, which
specify the minimum or maximum number of relationship instances that an individual entity can
participate in
- Minimum cardinality can be 0 or 1
- If 0: partial participation
- If 1: total participation
- Maximum cardinality can be 1 or N
- relationship types are often characterized by their maximum cardinalities
- 4 options for binary relationships types: 1:1, 1:N, N:1, and M:N
.Catalog - ANSWER-- heart of DBMS
- contains the date definitions (metadata) of your DB application
- stores the definitions of the views, logical and internal data models, and synchronizes these three data
models to ensure consistency
.Categorization - ANSWER-- A category is a subclass that has several possible superclasses
- each superclass represents a different entity type
- the category represents a collection of entities that is a subset of the union of the superclasses
- corresponds to an entity inheriting only the attributes and relationships of that superclass it is a
member of (selective inheritance)
- a categorization can be total or partial
Total: all entities of the superclasses belong to the subclass
Partial: not all entities of the superclasses belong to the subclass
.Categorization based on architecture - ANSWER-Centralized DBMS
- data is maintained on a single centralized server
Client Server
- active clients request services from passive servers
- fat server versus fat client variant
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