The DBEnvironment determines both what data can be accessed
in a transaction and what data can be recovered.
Following a failure, a transaction can be recovered, or all data can
be recovered, as follows:
A transaction is one or more SQL statements
that together perform a unit of work on one or more databases in
a DBEnvironment. Work done within a transaction can be made permanent
(committed) or undone (rolled back).
After a system or hardware failure, all data within a DBEnvironment is recovered to a consistent
state. Changes performed by any transactions incomplete at failure
time are rolled back. Changes performed by transactions completed
before failure time are made permanent.
You can have more than one DBEnvironment on your system. When
you connect to a DBEnvironment, ALLBASE/SQL establishes a DBE
session for you. The query processor can process statements
only when you are in a DBE session. You can access any DBEnvironment
in either of the two following modes:
Single-user mode—only
one user or program can use a DBEnvironment.
Multiuser mode—more
than one user and/or program can use a DBEnvironment at the same
time.
