|Oracle Master Glossary||
lamp Text in angled brackets that appears on the status line when you are in a given mode (e.g., <Insert>, <Connected>, etc.).
LAN (Local Area Network) A limited-distance, high-speed, data communications network that allows various data processing resources to be connected and shared. Typically served by communications media such as Token Ring and Ethernet. Contrast with WAN (Wide Area Network). LANs are usually less expensive, easier to maintain, and offer better performance than WANs.
latch An internal lock held for a short time to ensure the consistency of internal shared data structures.
layout (1) The area of an editor in which you can create, modify, position, or delete objects while viewing their graphic representations. (2) Defines the format of the report output using SQL*ReportWriter objects.
layout editor The WYSIWYG, graphical design facility in SQL*Forms. The Layout Editor is a component of the Designer.
Layout menu Lists the set of layout objects and provides users access to their settings.
layout objects SQL*ReportWriter objects used to define the layout of a report. Layout objects are frames, repeating frames, fields, boilerplate, and anchors.
LDU Logical Disk Unit.
leading The vertical spacing between the baselines of two lines of text.
leaf In a database table in which the rows' data values imply a hierarchy, a row that has no children rows. The lowest-level row, or the row at the finest level of detail.
Leaf menu item Represents a command that the user may select. It has no submenu.
leaf view A view with no children.
least privilege The concept where a user is granted the least number of privileges necessary to perform a job or task.
least upper bound The highest classification and the union of the categories of two or more labels.
level The number of rows between a given row and the root row in a database table in which the rows' data values imply a hierarchy. The root row is considered level 1, its children rows are level 2, and so on.
lexical delimiter characters Characters used during indexing to delimit words or numbers.
lexical reference A reference to a parameter used as a placeholder for text in a SQL SELECT statement. For a lexical reference, you must precede the parameter name with an ampersand (&).
lexical rules The rules whereby a stream of text is broken down into tokens.
LGF file The standard dialogue file that contains the information used by the autologon facility for logging on to(connecting to) the server process and host system. See also autologon facility and dialogue files.
LGO file The standard dialogue file that contains the information used by the autologon facility for logging off (disconnecting from) the host system. See also autologon facility and dialogue files.
LGWR (Log Writer task) One of five background tasks used by an ORACLE instance. Log Writer writes redo log entries to disk. Also called LGWR process.
library (1) In the Wang VS operating system, a directory of files. Equivalent to directory. (2) A collection of one or more PL/SQL program units that are stored together in a file or database, and that can be referenced by several displays at once.
library module A definition file of user-named PL/SQL functions and procedures. A library module can only contain one library.
limited search by field Ability to search for the occurrence of a term or word in a specific field such as the field for name or the field for title. See also field-directed searching.
line mode (1) Refers to use of a subset of ASCII characters for data that do not conflict with certain control characters used by modems and other communications equipment (such as DCX). Contrast with raw mode. (2) The state during which SQL*Net sends and receives strings using an expansion technique that reduces throughput 25% in exchange for more reliable data transmission.
link Data model object used to define a master/detail (parent-child) relationship between a SELECT statement and one or more groups owned by other queries. See also database link.
link file The name of a file to which a boilerplate object is linked, allowing you to import into your report layout at runtime, text and/or graphics currently stored in the named file. You can create links using the CLI command CREATE with the /LINK switch.
list box A list of items within a dialog box. Usually, the list box offers choices for selection, and it is scrollable. See also scroll bar.
list of values A list of the valid values for a field in the design interface.
listener See TNS listener.
Listener Control Utility (LSNRCTL) A utility included with SQL*Net V2 to control various functions, such as to start, stop, and get the status of the TNS listener.
LISTENER.ORA A configuration file that describes one or more TNS listeners on a server.
listener process The server process that listens for and accepts incoming connection requests from client applications. ORACLE listener processes start up ORACLE database Shadow processes to handle subsequent communications with the client.
LOAD The opposite of DUMP and DUMP_II. See also LOAD_II.
loadable driver A driver that need not be loaded into RAM until it is required. It can be added in and called at any time and need not be permanently linked with the rest of the ORACLE code, thus freeing up memory and allowing the user of SQL*Net to change versions of a SQL*Net driver without having to relink the ORACLE tools. See also driver.
LOADREP Executable that loads an ASCII report definition file into an ORACLE database. LOADREP is used in conjunction with the DUMPREP command.
LOAD_II program An AOS/VS utility program that restores material dumped from disk by either the DUMP command or the DUMP_II program.
local area network See LAN.
local database (1) The database on the computer running the application. (2) The database to which an application is connected. This database parses and executes all SQL statements generated by the application. Contrast with remote database.
local tables See user-owned tables.
location See business location.
location list A set of bit strings that indicate the documents which contain each indexed word. See also pointer file.
location transparency A distributed database characteristic that allows applications to access data tables without knowing where they reside. All data tables appear to be in a single database, and the system determines the actual data location based on the table name. The user can reference data on multiple nodes in a single statement, and the system automatically and transparently routes (parts of) SQL statements to remote nodes for execution if needed. The data can move among nodes with no impact on the user or application.
lock (1) (noun) A temporary "hold" on a database resource, acquired by a user while using that resource, to support concurrency.
A lock is a mechanism intended to prevent destructive interaction between users accessing ORACLE data.
(Destructive interaction can be interpreted as any interaction that incorrectly updates data or incorrectly alters underlying data structures.) Locks are used to achieve consistency and integrity.There are numerous types of locks; see dictionary locks and data locks.
(2) (verb) To request a lock on a database table or row with the SQL statement LOCK, in order to temporarily restrict other users' access to it and to perform updates or queries.
(3) In the Designer, a restriction that assigns temporary ownership, or control, of a SQL*Forms (Design) object (e.g., a text item or boilerplate object) to a window. A lock prevents the designer from changing the properties of an object in another property sheet.
lock escalation A property of some databases (not ORACLE) that causes a lock to be placed on a larger amount of data. For example, a row-level lock might be escalated to a table-level lock.
lock manager A software facility that allows multiple processes to coordinate resource sharing. In a loosely coupled system, these processes can run on different nodes and so require a distributed lock manager. The lock manager allows applications to synchronize access to resources such as data, software, and peripheral devices, so that concurrent requests for the same resource are coordinated.
LOCK mode A mode in which a data lock can be acquired. The six modes are SHARE, SHARE UPDATE, SHARE EXCLUSIVE, ROW SHARE, ROW EXCLUSIVE, and EXCLUSIVE. Each mode defines the restrictions placed by that lock. The most restrictive mode is EXCLUSIVE and the least restrictive is SHARED.
lockword A security feature that ensures the database is installed only by those granted special authorization.
log allocation The allocation of another portion of an online redo log file to a running instance for writing redo log entries. Relevant primarily for shared disk systems, when multiple instances must all write to the same redo log file.
log in (or log on) To perform a sequence of actions at a terminal that establishes a user's communication with the operating system and sets up default characteristics for the user's terminal session.
log off (or log out) To terminate interactive communication with the operating system, and end a terminal session.
log sequence number A unique number identifying a specific redo log file. Assigned by ORACLE Server and used by the DBA during archiving and recovery of log files.
Log Writer See LGWR.
logging A feature in which information about an individual connection is written to a log file. See also tracing.
logical attribute A logical attribute describes an attribute by function rather than by appearance. It provides a mechanism for specifying a view on character mode platforms where the set of available attributes may vary among terminals with different display capabilities.
logical database structure Structure determined by one or more tablespaces, the database's schema objects (e.g., tables, views, indexes, clusters, sequences, stored procedures), and the logical storage structures, including tablespaces, segments, and extents. All these elements dictate how the physical space of a database is used. The schema objects and the relationships among them form the relational design of a database.
logical expression A statement about a relationship between two or more field values and/or constants, which may be true or false. Logical expressions are used in WHERE clauses in SQL statements and in search criteria in SQL*Forms.
logical file A character string used to refer to files or devices by other than their specific names. Also known as logical assignment or logical name.
logical operator The logical operators are AND, OR, and NOT. You use AND and OR to combine conditions for a query, and NOT to make a negative condition, such as NOT BETWEEN. See also operator and condition.
logical page One page of your actual report, even if it is displayed on several physical pages.
logical unit of work Synonym for transaction.
login account A username and password to use ORACLE Server. This account is usually separate from an operating system account.
logon string A user-specified command line, used to run an application that is connected to either a local or remote database. The logon string either explicitly includes a connect string or implicitly uses a default connect string.
long column Each entry in a long column can be up to 65,535 characters long. Users cannot apply SQL functions to long columns, nor use long columns in the CONDITIONS and SORT regions of the screen.
LONG datatype A standard ORACLE datatype. A LONG column may contain any printable character, such as A, 3, &, or blanks, and can be any length from 1 to 65K characters; alternatively it can be null.
LONG RAW datatype A standard ORACLE datatype similar to LONG, but which contains raw binary data. Values entered into LONG RAW columns must be in hexadecimal notation.
lookup column usage A detailed column usage used by CASE*Generator to specify a lookup field on a form or report. A lookup column usage is always part of a lookup table usage.
lookup data Data retrieved into a lookup field on a form or a report.
lookup field A non-base table field on a generated form or report that displays descriptive values associated with a foreign key in the base table of the block or group. The descriptive values are derived from the table to which the foreign key relates.
look-up item An item whose value is derived from a column in a table other than its own base table.
lookup table usage A detailed table usage used by CASE*Generator to specify non-base table fields to be incorporated in a block or group. The base table has a foreign key linking it to the lookup table. Code is included in the generated application to implement a join condition based upon the foreign key. This ensures that the values displayed in the lookup table fields are consistent with the values in the base table fields. Note that non-base table fields may be derived from other sources.
loosely coupled architecture A shared-disk architecture that enables multiple processing nodes to cooperate without sharing memory. Each node operates independently of the other nodes, except when sharing a resource such as a data file or print queue.
lost updates A problem associated with multiple-user databases that can occur when multiple users update the same data and some updates are lost, or the final effect is not cumulative. ORACLE Server prevents lost updates.
LRU algorithm Least-recently used algorithm.
LU (Logical Unit) A unit in a System Network Architecture (SNA) network that addresses and interacts with the host. Typically in a LAN gateway system, a LU is analogous to a session, a terminal-to-mainframe connection.
LU0 A component of IBM's System Network Architecture (SNA), an unstructured protocol that can be called from VTAM. This protocol is used by Oracle for mainframe-to-mainframe connections along with the LU2 protocol. See VTAM.
LU1 Same as asynchronous transmission.
LU2 Also known as 3270 data streams, this IBM SNA protocol was designed for block mode terminal-to-host communications.
LU6.2 Also known an APPC, a component of IBM's System Network Architecture (SNA). It is a peer-to-peer protocol that can be run on a Token Ring (IEEE 802.5 network) to support LANs or on a synchronous SDLC line for long haul (WAN) communications. LU6.2 is a higher-level transport protocol that defines a session between two tool or application programs. It is a product-independent LU type. See also APPC.
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