Modern Database Management - Chapter 5
All of the following are valid datatypes in Oracle 11g EXCEPT: A) varchar2. B) boolean. C) blob. D) number.
boolean.
Another form of denormalization where the same data are stored in multiple places in the database is called:
data replication.
A detailed coding scheme recognized by system software for representing organizational data is called a(n):
data type.
The value a field will assume unless the user enters an explicit value for an instance of that field is called a(n):
default value.
A command used in Oracle to display how the query optimizer intends to access indexes, use parallel servers and join tables to prepare query results is the:
explain plan.
A contiguous section of disk storage space is called a(n):
extent.
A disadvantage of partitioning is:
extra space and update time.
A(n) ________ is a technique for physically arranging the records of a file on secondary storage devices.
file organization
One field or combination of fields for which more than one record may have the same combination of values is called a(n):
secondary key.
Common denormalization opportunities
two entities with a one-to-one relationship. a many-to-many relationship with nonkey attributes. reference data.
All of the following are objectives when selecting a data type EXCEPT: A) represent all possible values. B) improve data integrity. C) support all data manipulations. D) use a lot of storage space
use a lot of storage space.
Horizontal partitioning makes sense:
when different categories of a table's rows are processed separately.
A rule of thumb for choosing indexes is to:
• be careful indexing attributes that may be null. • index each primary key of each table. • use an index when there is variety in attribute values.
A requirement to begin designing physical files and databases is:
A) normalized relations. B) definitions of each attribute. C) technology descriptions.
Parallel query processing speed is not significantly different from running queries in a non-parallel mode.
Answer: FALSE
Reduced uptime is a disadvantage of partitioning.
Answer: FALSE
SOX stands for the Sorbet-Oxford Act.
Answer: FALSE
The logical database design always forms the best foundation for grouping attributes in the physical design.
Answer: FALSE
The query processor always knows the best way to process a query.
Answer: FALSE
The smallest unit of named application data is a record.
Answer: FALSE
Using an index for attributes referenced in ORDER BY and GROUP BY clauses has no significant impact upon database performance.
Answer: FALSE
A hashing algorithm is a routine that converts a primary key value into a relative record number.
Answer: TRUE
A pointer is a field of data that can be used to locate a related field or record of data.
Answer: TRUE
A range control limits the set of permissible values that a field may assume.
Answer: TRUE
A tablespace is a named set of disk storage elements in which physical files for the database tables may be stored.
Answer: TRUE
Along with table scans, other elements of a query can be processed in parallel.
Answer: TRUE
Clustering allows for adjacent secondary memory locations to contain rows from several tables.
Answer: TRUE
Denormalization almost always leads to more storage space for raw data.
Answer: TRUE
Efficient database structures will be beneficial only if queries and the underlying database management system are tuned to properly use the structures.
Answer: TRUE
Fast data retrieval is one factor to consider when choosing a file organization for a particular database file.
Answer: TRUE
Hash partitioning spreads data evenly across partitions independent of any partition key value.
Answer: TRUE
In a sequential file, the records are stored in sequence according to primary key.
Answer: TRUE
Indexes are most useful for columns that frequently appear in WHERE clauses of SQL commands, either to qualify the rows to select or for linking.
Answer: TRUE
Keeping the zip code with the city and state in a table is a typical form of denormalization.
Answer: TRUE
One decision in the physical design process is selecting structures.
Answer: TRUE
One objective of selecting a data type is to minimize storage space.
Answer: TRUE
Requirements for response time, data security, backup and recovery are all requirements for physical design.
Answer: TRUE
Security is one advantage of partitioning.
Answer: TRUE
Sensitivity testing involves ignoring missing data unless knowing a value might significantly change results.
Answer: TRUE
Which of the following is an objective of selecting a data type? A) Represent a small number of possible values B) Maximize storage space C) Limit security D) Improve data integrity
Improve data integrity
Within Oracle, the named set of storage elements in which physical files for database tables may be stored is called a(n):
tablespace.
Database access frequencies are estimated from:
transaction volumes.
Indexes are most useful on small, clustered files.
Answer: FALSE
________ partitioning distributes the columns of a table into several separate physical records.
Vertical
A(n) ________ is a routine that converts a primary key value into a relative record number.
hashing algorithm
A(n) ________ is a field of data used to locate a related field or record.
pointer
Which type of file is most efficient with storage space?
Sequential
A default value is the value that a field will always assume, regardless of what the user enters for an instance of that field.
Answer: FALSE
A file organization is a named portion of primary memory.
Answer: FALSE
A join index is a combination of two or more indexes.
Answer: FALSE
A key is a data structure used to determine the location of rows in a file that satisfy some condition.
Answer: FALSE
Adding notations to the EER diagram regarding data volumes and usage is of no value to the physical design process.
Answer: FALSE
An extent is a named portion of secondary memory allocated for the purpose of storing physical records.
Answer: FALSE
Denormalization is the process of transforming relations with variable-length fields into those with fixed-length fields.
Answer: FALSE
Free range partitioning is a type of horizontal partitioning in which each partition is defined by a range of values for one or more columns in the normalized table.
Answer: FALSE
Horizontal partitioning is very different from creating a supertype/subtype relationship.
Answer: FALSE
Horizontal partitioning refers to the process of combining several smaller relations into a larger table.
Answer: FALSE
One method to handle missing values is to substitute an exact value.
Answer: FALSE
Vertical partitioning means distributing the columns of a table into several separate physical records.
Answer: TRUE
In which type of file is multiple key retrieval not possible?
Hashed
Which type of file is easiest to update?
Hashed
Horizontal partitioning methods in Oracle
Key range partitioning Hash partitioning composite partitioning
In which data model would a code table appear?
Physical
Sensitivity testing involves:
checking to see if missing data will greatly impact results.
A method to allow adjacent secondary memory space to contain rows from several tables is called:
clustering.
The storage format for each attribute from the logical data model is chosen to maximize ________ and minimize storage space.
data integrity
Designing physical files requires ________ of where and when data are used in various ways.
descriptions
An advantage of partitioning is:
efficiency.
In most cases the goal of ________ dominates the design process.
efficient data processing
Factors to consider when choosing a file organization is:
fast data retrieval. security. efficient storage
The smallest unit of application data recognized by system software is a:
field.
A file organization that uses hashing to map a key into a location in an index where there is a pointer to the actual data record matching the hash key is called a:
hash index table.
Distributing the rows of data into separate files is called:
horizontal partitioning.
An index on columns from two or more tables that come from the same domain of values is called a:
join index.
While Oracle has responsibility for managing data inside a tablespace, the tablespace as a whole is managed by the:
operating system.
A method that speeds query processing by running a query at the same time against several partitions of a table using multiprocessors is called:
parallel query processing.
An integrity control supported by a DBMS is:
range control.
A key decision in the physical design process is:
selecting structures.
A method for handling missing data is to:
substitute and estimate for the missing data. track missing data with special reports. perform sensitivity testing.
