Glossary
L
labeled duration
A number that represents a duration of
years, months, days, hours, minutes, seconds, or microseconds.
large object (LOB)
A sequence of bytes, where the length can
be up to 2 gigabytes. It can be any of three types: BLOB (binary), CLOB
(single-byte character or mixed) or DBCLOB (double-byte character).
length attribute
A value associated with a string that
represents the declared fixed length or maximum length of the string.
LEN node
Low-entry networking node.
list prefetch
An access method that takes advantage of
prefetching even in queries that do not access data sequentially. This is done
by scanning the index and collecting RIDs in advance of accessing any data
pages. These RIDs are then sorted, and data is prefetched using this list.
load copy
A backup image of data that was loaded at
a previous time and can be restored during roll-forward recovery.
load utility
A nontransactional utility that performs
block updates of table data. Contrast with import utility.
LOB
Large object.
LOB locator
A mechanism that allows an application
program to manipulate a large object value in the database system. A LOB
locator is a simple token value that represents a single LOB value. An
application program retrieves a LOB locator into a host variable and can then
apply SQL functions to the associated LOB value via the locator.
local database
A database that is physically located on
the workstation in use. Contrast with remote database.
local database directory
A directory where a database physically
resides. Databases that are displayed in the local database directory are
located on the same node as the system database directory.
local table lock
A table lock that is acquired only on a
single database partition.
local update
An update to the base table, not to the
replica.
locator
See LOB locator.
lock
(1) A means of serializing events or access to
data.
(2) A means of preventing uncommitted changes
made by one application process from being perceived by another application
process and for preventing one application process from updating data that is
being accessed by another process.
lock escalation
In the database manager, the response that
occurs when the number of locks issued for one agent exceeds the limit
specified in the database configuration; the limit is defined by the MAXLOCKS
configuration parameter. During a lock escalation, locks are freed by
converting locks on rows of a table into one lock on a table. This is repeated
until the limit is no longer exceeded.
locking
The mechanism used by the database manager
to ensure the integrity of data. Locking prevents concurrent users from
accessing inconsistent data.
log
(1) See database log.
(2) A file used to record changes made in a
system.
log head
The oldest written log record in the
active log.
logical node
A node on a processor when more than one
node is assigned to that processor. See also node.
logical operator
A keyword that specifies how multiple
search conditions are to be evaluated (AND, OR) or if the logical sense of a
search condition is to be inverted (NOT).
logical unit (LU)
In SNA, a port through which an end user
accesses the SNA network to communicate with another end user. An LU may be
capable of supporting many sessions with other LUs.
logical unit 6.2 (LU 6.2)
The LU type that supports sessions between
two applications using APPC.
log partition
The log file on each database partition
that records database activity for that database partition.
log record
A record of an update to a database
performed during a unit of work. This record is written after the log tail of
the active log.
log tail
The log record that was written most
recently in an active log.
long string
A varying-length string whose maximum
length is greater than 254 bytes.
long table space
A table space that can store only long
string or large object (LOB) data.
low-entry networking node (LEN node)
A type 2.1 node that supports independent
LU protocols but does not support CP-CP sessions. It can be a peripheral node
attached to a boundary node in a subarea network, an end node attached to an
APPN network node in an APPN network, or a peer-connected node directly
attached to another LEN node or APPN end node.
LU
Logical unit.
LU 6.2
See logical unit 6.2.
LU type
The classification of a logical unit in
terms of the specific subset of SNA protocols and options it supports for a
given session, specifically:
- The values allowed in the session activation request
- The usage of data stream controls, function management headers, request
unit parameters, and sense data values
- Presentation services protocols such as those associated with function
management headers
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