The concept of transaction is a basic one in database theory. Yet, in
some cases the atomicity of a transaction may be relaxed. This happens
either to avoid the damage inflicted by the fact that many data eleme
nts are locked in long transactions, or to support different view-poin
ts of the database that may relax atomicity constraints. This paper de
fines the concept of transaction, in the environment of PARDES-an inte
lligent active database and outlines a model in which different modes
of consistency co-exist as local decisions. These modes are defined an
d analyzed. Among the basic modes are: fully consistent (consistent at
all times), quasi consistent (eventually consistent) and loosely cons
istent (failures in derivations are not compensated). This is an exten
sion to the active database definition language that enables the suppo
rt of implementation considerations using high-level abstractions.