Fixed and Variable length Records


and how they are related to direct and sequential access methods.

  • A record consists of fields
    • every field has a data type
      • data types commonly are made up of fixed length of bits (usually 32)
  • The length of a record is calculated through the total number of bits in a record
  • A length of a general record is is 32 Bits +variable number of Bits + 64 Bits
  • Note: the general length is the same, but is dependent of the length of the central name.

The key difference between Fixed and Variable length Records is that the central "variable" length is...
  • in the Fixed Length record is set to a certain length and the location is simply calculated
  • in the Variable Length Record the record size is irrelevant because all records are indexed sequentially in a header record.


Created by: Daniel Gillo
Last modification: 13th September 2011

Sources:
  • Jones, Richard. Computer Science Java Enabled. Victoria: IBID Press, 2004