37. A compaction method according to claim 35 wherein said first group of fields comprises two separate fields of the database.
35. A compaction method, which comprises: selecting a first group of fields from a database; reading a first group of data values from a record of the database, each individual data value being read from a separate field from within the first group of fields to form a first data value combination; assigning a numeric equivalent to the first data value combination, such that the numeric equivalent uniquely determines the first data value combination; replacing the first data value combination with a representation of the numeric equivalent to create a compacted data value only if a field combining criterion based on the first group of fields, and dependent on a concentration level of unique data value combinations, is satisfied, the compacted data value being a reduced storage equivalent of the first data value combination; and creating a translation table which contains an entry that equates the data value combination with the assigned numeric equivalent, to provide for retranslation from the numeric equivalent to the data value combination.