Chapter 12 (File Management)

Question 1

What are some desirable properties of files?

Answer 1

Long-term existence

Shareable between processes

Structure

Question 2

What operation allows a process to perform functions on a file?

Answer 2

Open

Question 3

What is a field?

Answer 3

Basic element of data containing a single value

Question 4

T/F A field can only be fixed length

Answer 4

F, fixed or variable length

Question 5

What is a record?

Answer 5

Collection of related fields treated as a unit

Question 6

T/F A record cannot be variable length

Answer 6

F, it can

Question 7

What is a file?

Answer 7

Collection of similar records treated as a single entity

Question 8

What is a database?

Answer 8

Collection of related data (1 or more files)

Question 9

What are the criteria for choosing a file organization?

Answer 9

Rapid access

Ease of update

Economy of storage

Simple maintenance

Reliability

Question 10

List the five fundamental file organizations

Answer 10

Pile

Sequential file

Indexed sequential file

Indexed file

Direct or hashed file

Question 11

How does pile collect data?

Answer 11

In the order it arrives

Question 12

How is data accessed in pile?

Answer 12

Exhaustive search

Question 13

What is the purpose of pile?

Answer 13

Accumulate a mass of data and save it

Question 14

Which file organization may be useful to store data prior to processing it?

Answer 14

Pile

Question 15

T/F In a sequential file, some fields are different

Answer 15

F, all are the same

Question 16

What are the attributes of a sequential file?

Answer 16

Field names and lengths

Question 17

Where are new records placed for a sequential file?

Answer 17

Log file or transaction file

Question 18

Where is a sequential file useful?

Answer 18

Batch processing

Question 19

How can additions be handled in an indexed sequential file?

Answer 19

Overflow file

Question 20

What’s special about an indexed sequential file?

Answer 20

Reduces time to access a single record while still providing sequential processing

Question 21

What’s the difference between a partial and exhaustive index?

Answer 21

Partial index only has pointers to records having the field of interest. Exhaustive index has pointers to every record

Question 22

When are direct or hash file mostly useful?

Answer 22

If records are only accessed one at a time

Question 23

How are indexes often implemented?

Answer 23

B-trees

Question 24

What’s the primary benefit of the B-tree for indexes?

Answer 24

Fewer disk accesses

Question 25

What is a directory?

Answer 25

A file owned by the OS and managed by the file management system

Question 26

What information does a directory contain?

Answer 26

Attributes, location, and ownership

Question 27

What are some directory operations?

Answer 27

Search Create file Delete file List directory Update directory

Question 28

T/F Every level of a directory structure may contain files and subdirectories

Answer 28

T

Question 29

What are two issues with file sharing?

Answer 29

Access rights Simultaneous access

Question 30

What are the typical classes for access rights?

Answer 30

Specific user Group of users All

Question 31

What are some examples of access rights?

Answer 31

None Knowledge Execution Reading Appending Updating Changing protection Deletion

Question 32

What are two approaches for simultaneous access?

Answer 32

Lock the file when it is to be updated Lock individual records during update

Question 33

When is a blocking of records performed?

Answer 33

When writing data

Question 34

List three blocking methods

Answer 34

Fixed Variable-length spanned Variable-length unspanned

Question 35

What are the properties of the variable-length spanned blocking method?

Answer 35

Variable-length records which may span blocks Unlimited record size May require multiple I/O's

Question 36

What are the properties of the variable-length unspanned blocking method?

Answer 36

Variable-length records which do not span blocks May cause internal fragmentation

Question 37

What does a file consist of?

Answer 37

Collection of blocks

Question 38

What are two management issues for secondary storage management?

Answer 38

Allocating blocks to files Maintaining a list of free blocks

Question 39

What are some file allocation issues?

Answer 39

Whether to allocate the maximum space required all at once, or to allocate space in portions If portions are used, how big should a portion be? If portions are used, how to keep track of the portions?

Question 40

What are some techniques for free space management?

Answer 40

Bit tables Chained free portions Indexing Free block list