A sequence of bytes with a size ranging from 0 bytes to 2GB minus 1 byte. It can be any of three types: binary large object (binary), character large object (single-byte character or mixed), or double-byte character large object (double-byte character).
large table space
A table space that can store only long strings, large objects (LOBs), or index data.
latency
The time required for updates made to a replication source to appear in a replication target.
leaf page
A page containing pairs of keys and record identifiers that points to actual data.
left outer join
The result of a join operation that includes the matched rows of both tables being joined and preserves the unmatched rows of the first table.
list prefetch
An access method that takes advantage of prefetching even in queries not accessing data sequentially. A list prefetch is done by scanning the index and collecting record identifiers before any data pages are accessed. These record identifiers are then sorted, and data is prefetched using this list.
load copy
A backup image of data previously loaded and that can be restored during roll forward recovery.
load module
A program unit that is suitable for loading into main storage for execution. A load module is the output of a linkage editor.
load utility
A nontransactional utility that performs block updates of table data.
LOB
See [large object]
LOB locator
A mechanism that allows an application program to manipulate a large object (LOB) 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 using the locator.
local database
A database that is physically located on the workstation in use.
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.
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
The response that occurs when the number of locks issued for one agent exceeds the limit specified in the database configuration. This 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) A file that records changes made in a system.
(2)
See also [database log]
log file
(1) A record that monitors a database's activity. Log files are essential to the backup and recovery process.
(2) A file that is produced by the Information Catalog Center when it imports a tag language file into the information catalog. This file records the times and dates when the import process started and stopped and any error information for the process.
logical agent
An agent that represents the client or application connection.
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).
long string
A variable-length string whose maximum length is 32700 bytes.
