table is a descendent of the one before it,
and the first table is a descendent of the
last table.
referential integrity
The state of a database in which all
values of all foreign keys are valid.
Maintaining referential integrity requires
the enforcement of referential constraints
on all operations that change the data in a
table on which the referential constraints
are defined.
referential structure
A set of tables and relationships that
includes at least one table and, for every
table in the set, all the relationships in
which that table participates and all the
tables to which it is related.
refresh age
The time duration between the current
time and the time during which a
materialized query table was last
refreshed.
registry
See registry database.
registry database
A database of security information about
principals, groups, organizations,
accounts, and security policies.
relational database
A database that can be perceived as a set
of tables and manipulated in accordance
with the relational model of data.
relational database management system
(RDBMS)
A collection of hardware and software
that organizes and provides access to a
relational database.
relational schema
See SQL schema.
relationship
A defined connection between the rows of
a table or the rows of two tables. A
relationship is the internal representation
of a referential constraint.
relative byte address (RBA)
The offset of a data record or control
interval from the beginning of the storage
space that is allocated to the data set or
file to which it belongs.
remigration
The process of returning to a current
release of DB2 following a fallback to a
previous release. This procedure
constitutes another migration process.
remote
Any object that is maintained by a remote
DB2 subsystem (that is, by a DB2
subsystem other than the local one). A
remote view, for example, is a view that is
maintained by a remote DB2 subsystem.
Contrast with local.
remote subsystem
Any relational DBMS, except the local
subsystem, with which the user or
application can communicate. The
subsystem need not be remote in any
physical sense, and might even operate
on the same processor under the same
z/OS system.
reoptimization
The DB2 process of reconsidering the
access path of an SQL statement at run
time; during reoptimization, DB2 uses the
values of host variables, parameter
markers, or special registers.
reordered row format
A row format that facilitates improved
performance in retrieval of rows that have
varying-length columns. DB2 rearranges
the column order, as defined in the
CREATE TABLE statement, so that the
fixed-length columns are stored at the
beginning of the row and the
varying-length columns are stored at the
end of the row. Contrast with basic row
format.
REORG pending (REORP)
A condition that restricts SQL access and
most utility access to an object that must
be reorganized.
REORP
See REORG pending.
repeatable read (RR)
The isolation level that provides
maximum protection from other executing
application programs. When an
application program executes with
repeatable read protection, rows that the
program references cannot be changed by
other programs until the program reaches
544 Application Programming Guide and Reference for Java
™
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
To Next Page
Loading...
Need help?
General