File Organisation

Question 1

File

Answer 1

A file is collection of related records

Question 2

Record

Answer 2

A record is a collection of related fields

Question 3

Variable length field

Answer 3

Variable length field has different number of bytes in each record. Variable length field makes it difficult to calculate how much storage space will be required
Variable length field are slower to process by computer as start and end locations have to be calculated at read/write time
Variable length field saves storage space as no blank space
E.g. - Name, Address, email address.

Question 4

Fixed length field

Answer 4

Fixed length field has the same number of bytes in each record. Fixed length field makes it easier to calculate how much storage space will be required. Fixed length records are quicker to process by computer as start and end locations are known.
E.g. - Gender, Date Of Birth.

Question 5

Serial File

Answer 5

Data is stored in the order in which it was entered. No order to the data is maintained. Useful for storing transactional and initialisation files. To add to a serial file the new record is appended to the end of the file.

Question 6

Sequential Files

Answer 6

Data is stored in the order of a key filed. Order is maintained when new records are added. Useful for storing master files. To add to a sequential file, a new file is made by copying the old file until an insertion is required then inserting the new record and copying the rest of the file. The old file is then deleted.

Question 7

Linear search

Answer 7

An algorithm that finds a value in a list by checking each item in order until a match is found

Question 8

Binary search

Answer 8

An algorithm that works by repeatedly dividing in half the portion of the list that could contain the item, until you’ve narrowed down the possible locations to just one.

Question 9

Direct access

Answer 9

storing data in a file where any record can be accessed directly, without having to read through the records that come before it

Question 10

Overflow

Answer 10

overflow describes a situation where a disk block is full
and a new record requires somewhere to be stored. the new record will be stored in this overflow area.

Question 11

Indexed sequential

Answer 11

storing data where records are physically arranged in a sequential order, but an additional index is maintained to allow for quick random access to individual records based on a key value