1.6 Organisation of Data Flashcards

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1
Q

Files

A

Is a collection of records with common properties

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2
Q

Fixed length field

A

All records are exactly the same length

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3
Q

Variable length field

A

The length of each record varies

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4
Q

Master Files

A

Are a collection of records pertaining to one of the main subjects of an information system.

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5
Q

Transaction file

A

Is used to hold data during transaction processing, it is later used to update the master file

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6
Q

Sequential file access

A

Is the access of files in the order that they are stored.

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7
Q

Advantages of Sequential file access

A

Easy to implement and use

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8
Q

Disadvantages of sequential file access

A

Slow or inefficient for random access operations when working with large files

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9
Q

Indexed sequential file access

A

Is either sequential access where the files are accessed in the order they are entered, or it is indexed

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10
Q

Advantages of indexed sequential file access

A

Can access the files quickly and efficiently if it is properly organised.
Reduces the amount of sequential access used

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11
Q

Disadvantages of indexed sequential file access

A

Expensive as it requires special operators.
Requires more storage space.

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12
Q

Direct/random file access

A

Is where data is accessed randomly rather than sequentially

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13
Q

Advantages of direct/random file access

A

Sorting of the records is not required.
Access the required records immediately

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14
Q

Disadvantages of direct/random file access

A

Expensive.
Less storage compared to sequential file access

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15
Q

Why do we need file safety procedures?

A

So that we can minimise the damage caused after the incident

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16
Q

Why do we need different generations of files?

A

This allows us to have multiple backups making the files even more secure

17
Q

Why do we archive files?

A

To avoid losing all data, accidently or on purpose

18
Q

Four examples of data checks

A

Format Check
Consistency Check
Uniqueness Check
Presence Check