1. Any of a number of methods to reduce unused or unusable space
in primary, secondary, or other memory. See memory compaction.
2. Removal of redundant data from a record. Many systems work
with fixed-length records as a convenient method of handling files.
This has the disadvantage that all records must be capable of
holding the longest record, giving uneconomic use of storage. The
fixed-length records can be processed (compacted) into a
variable-length form. One method involves the removal of trailing
spaces; another involves the replacement of long strings of
identical characters by a flag that
indicates the occurrence of such a string, together with a count of
the number of characters and a single instance of the character.
Compaction will require CPU time when the record is stored and again
when it is unpacked to fixed-length form, but the consequent saving
in storage may justify this.