The entity integrity rule requires that ____.
all primary key entries are unique
a part of the key may be null
foreign key values do not reference primary key values
duplicate object values are allowed
The referential integrity rule requires that ____.
every null foreign key value must reference an existing primary key value
an attribute have a corresponding value
every non-null foreign key value reference an existing primary key value
you delete a row in one table whose primary key does not have a matching foreign key value in another table
The ____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
subtype discriminator
inheritance
specialization hierarchy
entity supertype
Every subtype can have ____ supertype to which it is directly related.
none
only one
one or many
many
A specialization hierarchy can have ____ levels of supertype/subtype relationships.
The property of ____ enables an entity subtype to inherit the attributes and relationships of the supertype.
One important inheritance characteristic is that all entity subtypes inherit their ____ attribute from their supertype.
primary key
natural key
foreign key
surrogate key
What feature is a DDBMS disadvantage?
Processor independence
User-friendly interface
Security
Faster data access
What feature is a DDBMS advantage?
Reduced operating cost
Complexity of management and control
Increased storage requirements
Increased training cost
A database is composed of several parts known as database ____.
sections
fragments
partitions
parts
Under the ____ scenario, multiple processes run on different computers sharing a single data repository.
Homogeneous
a
The ____ scenario describes a fully distributed DBMS with support for multiple data processors and transaction processors at multiple sites.
b
____ distributed database systems integrate only one type of centralized DBMS over a network.
Homogenous
Heterogeneous
Fully heterogeneous
Fully homogeneous
____ transparency allows the integration of several different local DBMSs under a common, or global, schema.
Transaction
Performance
Distribution
Heterogeneity
The ____ contains the description of the entire database as seen by the database administrator.
distributed global dictionary
distributed data dictionary
distributed global schema
distributed data schema
____ fragmentation allows us to break a single object into two or more segments or fragments.
Horizontal
Vertical
Data
Mixed
With ____ data allocation, the database is divided into several disjointed parts and stored at several sites.
centrialized
decentralized
partitioned
replicated
The ____ rule requires that all copies of data fragments be identical.
shared fragment
mutual consistency
horizontal fragmentation
replication
Which of the following is a problem with a centralized database?
high cost
Good performance from remote locations
Poor performance from the main location
Lack of storage
