key
A key is an ordered list of pointers to the rows of
a table—much like the index of a book.
Existence of a key for an column can greatly
facilitate Rim's access to data rows during retrievals.
However, because keys need to be maintained, their
existence is detrimental to Rim's efficiency during database update.
Normally you will build a key for those columns
of a table which are most often referenced in query commands.
Rim will, in some circumstances, automatically build a key.
Columns for which keys have been built are referred to as
``keyed columns''.