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the other one needs. Neither of the processes will release its resource until it
has received the other's resource; therefore, neither process can proceed.</P>
<P><B>Decision Support System</B>--<I>See</I> <B>DSS</B>.</P>
<P><B>deferred frame</B>--A network frame delayed from transferring because the network
is busy.</P>
<P>DELETE--The SQL statement used to delete a row or rows from a table.</P>
<P><B>device driver</B>--The piece of software, supplied by the OS or hardware vendor,
that provides support for a piece of hardware such as a disk array controller or
a NIC.</P>
<P><B>disk array</B>--A set of two or more disks that might appear to the system
as one large disk. A disk array can be a software or hardware device.</P>
<P><B>DML commands</B>--Data Manipulation Language commands. The commands that allow
you to query and modify data within existing schema objects. Unlike the DDL commands,
a commit is not implicit. DML statements consist of <TT>DELETE</TT>, <TT>INSERT</TT>,
<TT>SELECT</TT>, and <TT>UPDATE</TT> statements; <TT>EXPLAIN PLAN</TT> statements;
and <TT>LOCK TABLE</TT> statements.</P>
<P><B>DSS</B>--Decision Support System. A DSS is characterized by large business
queries designed to provide valuable data that is used to make sound business decisions.</P>
<P><B>dynamic performance tables</B>--Tables created at instance startup and used
to store information about the performance of the instance. This information includes
connection information, I/Os, initialization parameter values, and so on.
<H2><FONT COLOR="#000077">E</FONT></H2>
<P><B>Ethernet</B>--A network hardware standard. Ethernet is probably the most-used
network type in the world.</P>
<P><B>equijoin</B>--A join statement that uses an equivalency operation. The converse
of this is the <B>nonequijoin</B> operation.</P>
<P><B>extent</B>--A group of contiguous data blocks allocated for a table, index,
or cluster. Extents are added dynamically as needed.
<H2><FONT COLOR="#000077">F</FONT></H2>
<P><B>foreign key</B>--An attribute requiring that a value must exist in another
object, if not NULL, and be its primary key.</P>
<P><B>frame</B>--<I>See </I><B>network frame</B>.</P>
<P><B>function</B>--A set of SQL or PL/SQL statements used together to execute a
particular function. Procedures and functions are identical except that functions
always return a value (procedures do not). By processing the SQL code on the database
server, you can reduce the number of instructions sent across the network and returned
from the SQL statements.
<H2><FONT COLOR="#000077">H</FONT></H2>
<P><B>HAL</B>--Hardware Abstraction Layer. A software layer closest to the hardware
that performs all hardware-specific functions. The HAL includes the device drivers.</P>
<P><B>Hardware Abstraction Layer</B>--<I>See</I> <B>HAL</B>.</P>
<P><B>hot data</B>--This term typically refers to frequently accessed data. Hot data
typically gets a good cache-hit rate.</P>
<P><B>hot database</B>--This term typically refers to a database that is currently
mounted, open, and servicing transactions. The instance is up and users are accessing
data.
<H2><FONT COLOR="#000077">I</FONT></H2>
<P><B>index</B>--A device designed to give you faster access to your data. An index
lets you avoid sequentially reading through data to find the item you are seeking.</P>
<P><B>initialization parameter</B>--A parameter read by Oracle at instance startup.
These parameters affect the Oracle configuration.</P>
<P>INSERT--The SQL statement used to insert a row into a table.</P>
<P><B>instance</B>--The Oracle instance consists of the SGA, the Oracle background
processes, and the datafiles that make up your database.</P>
<P><B>I/O</B> (<B>Input and Output [of data])</B>--This term can be used to describe
any type of data transfer but is typically associated with accesses to disk drives.
<H2><FONT COLOR="#000077">J</FONT></H2>
<P><B>join</B>--A query that selects data from more than one table. The data selected
from the different tables is determined by conditions specified within the <TT>FROM</TT>
clause of the statement. These conditions are called <B>join conditions</B>.</P>
<P><B>join condition</B>--The specification within the <TT>WHERE</TT> clause of a
query join that specifies the manner in which the rows in the different tables are
paired.
<H2><FONT COLOR="#000077">L</FONT></H2>
<P><B>LAN</B>--A local, high-speed network that uses network hardware such as Ethernet
or Token Ring and protocols such as TCP/IP and SPX/IPX.</P>
<P><B>lightweight process</B>--Sometimes known as a <B>thread</B>. Similar to a process
but shares the process context with other lightweight processes. A lightweight process
has much less overhead associated with it than does a normal process. A <B>thread
switch</B> (change between threads) has much less overhead than a process switch.</P>
<P><B>Local Area Network</B>--<I>See</I> <B>LAN</B>.</P>
<P><B>logical disk</B>--A term used to describe a disk that is in reality two or
more disks in a hardware or software disk array. It appears to the user as one large
disk when, in reality, it is two or more striped physical disks.
<H2><FONT COLOR="#000077">M</FONT></H2>
<P><B>main memory</B>--A term often used to describe RAM (Random Access Memory).
This is the part of the computer system used to store data being processed or data
that has recently been accessed. RAM is volatile and is not saved when the system
is powered off.</P>
<P><B>Massively Parallel Processor system</B>--<I>See</I> <B>MPP system</B>.</P>
<P><B>microkernel</B>--The core component of a microkernel operating system. The
microkernel contains the base components of the operating system. In a microkernel
architecture, OS functions usually done in the kernel (such as I/O and device-driver
support) are moved out of the kernel.</P>
<P><B>MPP system</B>--Massively Parallel Processor system. A multiprocessor computer
consisting of many independent processors that communicate through a complex, high-speed
bus.</P>
<P><B>multiprocessor system</B>--A computer that has two or more CPUs. A multiprocessor
can be an SMP (Symmetric Multiprocessor) or an MPP (Massively Parallel Processor)
system.
<H2><FONT COLOR="#000077">N</FONT></H2>
<P><B>NCA</B>--The Network Computing Architecture (NCA) is a standard for computing
over the network. The NCA was developed in conjunction with Oracle.</P>
<P><B>Network Computing Architecture</B>--<I>See</I> <B>NCA</B>.</P>
<P><B>network frame</B>--The structure sent across the network that contains user
data as well as network control information. The terms <B>network frame</B> and <B>network
packet</B> are sometimes interchangeable.</P>
<P><B>Network Interface Card</B>--<I>See</I> <B>NIC</B>.</P>
<P><B>network packet</B>--The structure built by the Network Protocol layer. This
structure includes user data as well as network and routing information.</P>
<P><B>NIC</B>--Network Interface Card. A piece of hardware used to network computers
together. A NIC can be one of several varieties including Ethernet, Token Ring, or
fiber optic.</P>
<P><B>nonequijoin</B>--A join statement that does not use an equality operation.
The converse of this is the <B>equijoin</B> operation.
<H2><FONT COLOR="#000077">O</FONT></H2>
<P><B>OCI</B>--Oracle Call Interface. The standard set of calls used to access the
Oracle database.</P>
<P><B>offline</B>--This term typically refers to a database that is currently closed
and not mounted. No users can connect to the database and no datafiles can be accessed.</P>
<P><B>OLTP</B>--Online Transaction Processing. An OLTP system is characterized by
large num-bers of users inserting and retrieving data in a somewhat unstructured
manner.</P>
<P><B>online</B>--This term typically refers to a database that is currently mounted,
open, and servicing transactions. The instance is up and users are accessing data.</P>
<P><B>Online Transaction Processing</B>--<I>See</I> <B>OLTP</B>.</P>
<P><B>optimizer</B>--A component of the Oracle RDBMS used to select SQL execution
plans in the most efficient and cost-effective manner. There are two optimizers:
a cost-based optimizer and a rules-based optimizer. Each determines the best execution
plan based on different criteria.</P>
<P><B>Oracle Call Interface</B>--<I>See</I> <B>OCI</B>.</P>
<P><B>outer join</B>--A join operation that uses the outer join operator (<TT>+</TT>)
in one of the join statements. The output of an outer join is the rows that satisfy
the join condition and those rows in the first table for which no rows in the second
table satisfy the join condition.
<H2><FONT COLOR="#000077">P</FONT></H2>
<P><B>package</B>--A collection of related, stored procedures or functions grouped
together.</P>
<P><B>packet</B>--<I>See</I> <B>network packet</B>.</P>
<P><B>paging</B>--An operating system function used to copy virtual memory between
physical memory and the paging file (<I>see</I> <B>virtual memory</B>). Paging is
used when the amount of virtual memory in use has exceeded the amount of physical
memory available. Paging is an expensive task in terms of performance and should
be avoided if possible.</P>
<P><B>Parallel Query option</B>--An add-on package to the Oracle RDBMS that allows
for concurrent processing of some functions.</P>
<P><B>Parallel Server option</B>--An add-on package to the Oracle RDBMS that allows
for multiple systems to share a common database. Each system has its own instance
but the database tables are shared. Data consistency is guaranteed by means of a
sophisticated locking mechanism.</P>
<P><B>physical memory</B>--The actual hardware RAM (Random Access Memory) available
in the computer for use by the operating system and applications.</P>
<P><B>PL/SQL</B>--A set of procedural language extensions that Oracle has added to
standard SQL. Procedures, functions, packages, and triggers are written in the PL/SQL
language.</P>
<P><B>primary key</B>--Attributes used to uniquely identify a row in a table.</P>
<P><B>procedure</B>--A set of SQL or PL/SQL statements used together to execute a
particular function. Procedures and functions are identical except that functions
always return a value (procedures do not). By processing the SQL code on the database
server, you can reduce the number of instructions sent across the network and returned
from the SQL statements.</P>
<P><B>program unit</B>--In Oracle, the term used to describe a package, a stored
procedure, or a sequence.
<H2><FONT COLOR="#000077">Q</FONT></H2>
<P><B>query</B>--A question. A <TT>SELECT</TT> statement is considered a query because