You can create a role using the CREATE ROLE statement, but you must have the CREATE ROLE system privilege to do so. Typically, only security
administrators have this system privilege.
Immediately after creation, a role has no privileges associated with it. To associate privileges with a new role, you must grant privileges or other roles to the new role.
You must give each role you create a unique name among existing usernames and role names of the database. Roles are not contained in the schema of
any user. In a database that uses a multibyte character set, Oracle recommends that each role name contain at least one single-byte character. If a
role name contains only multibyte characters, the encrypted role name/password combination is considerably less secure.
ad-hoc
Done on an irregular or spontaneous basis. An ad-hoc report, for example, is one that is designed on the spot and run only once, or maybe a very few times.
architecture
In the context of Oracle’s database, the term architecture refers to the overall design of the product, especially with reference to how the various individual components interact with each other. With Oracle, there is memory architecture, referring to how Oracle uses memory, process architecture--referring to the various processes that run to make an Oracle database work, and file architecture, referring to the way in which Oracle uses files.
Archive Log Destination
The location, usually a directory, to which Oracle copies redo log files before reusing them.
Archive Log File
The same as an archived log file. Many people use this term instead.
Archive Log Mode
A mode in which Oracle saves the entire redo log. As redo log files are filled, they are copied to another location, known as the archive log destination, for safekeeping. Running a database in archive log mode allows all committed changes to be recovered in the event of a failure.
Archived Log File
A redo log file that has been copied to the archive log destination. After copying, it is said to have been archived.
Asynchronously
When applied to processes, Oracle processes in particular, to execute asynchronously means to execute at the same time as other processes, without having to take turns.
Background Processes
Operating system processes that are always running, and that make Oracle work. On Windows NT, these are implemented as threads within an NT service, not as separate processes.
Bouncing
The process of stopping and starting something. To bounce a listener, means to stop and start the listener. To bounce a database, means to shutdown and startup the database.
Buffer
A memory area used to hold data. Oracle uses buffers to hold blocks of data read from the data files, and also uses a buffer to hold redo log entries.
Cache Hit Ratio
A ratio indicating how often Oracle goes to read a block, and finds it already in memory as opposed to having to read the block from disk.
Checkpoint
A number recorded in a database's control file that represents the highest redo log number for which changes have already been written back to the datafiles.
Clause
A portion of a long command that deals with a specific domain. Clauses are often, but not always, optional, and often begin with a keyword. The CREATE TABLE command, for example, has an optional storage clause that can be used to define storage characteristics for the table.
Cold Backup
A copy of the database files made while the database is shutdown and closed. A cold backup is often refered to as an offline backup.
Commit or COMMIT
Commit is both a specific command and an action. When you make changes to a database, you must tell Oracle when to make those changes permanent. When you do this, you are said to be committing the changes. The COMMIT command is the command that is typically used to commit a change.
Control File
A file hat Oracle uses to keep track of the rest of the database. Among other things, the control file contains the names and locations of all other database files.
Controllers
Usually refers to disk controllers. A disk controller is a component (usually a circuit board card) that manages one or more disks.
CPU
Central Processing Unit. That part of a computer that executes instructions. When database administrators talk of CPU, they are most often referring to CPU time. They may be concerned with the amount of CPU time required to execute a query, or with the amount of CPU time consumed by a given user.
Crash Recovery
The process of redoing changes that were lost during a system crash because the affected data blocks were contained only in memory. During crash recovery, the redo log files are read, and the changes reapplied to the datafiles.
cron jobs
Unattended batch jobs that are scheduled with the Unix cron utility.
Data Dictionary
A set of tables and views that Oracle uses to keep track of the tables, views, and other objects that you have defined.
Data Dictionary Cache
An area in the Shared Pool where Oracle stores frequently accessed data dictionary information so that it does not need to be continuously reread from disk.
Database
Oracle defines the term database to mean a collection of data that is treated as a unit. In practical terms, a database is a set of physical data files, control files, and redo log files.
Database Buffer Cache
An area in memory where Oracle keeps recently used data blocks so that they do not need to be constantly reread from disk.
Datafile
In Oracle, the term datafile is used to denote a file used to store user data. Datafiles may contain table data, index data, or
stored code.
DBA Management Pack
The set of Enterprise Manager applications used to perform basic database administration tasks.
Dedicated Server Process
A server process that is dedicated to one, specific user process.
Default Buffer Pool
A pool of buffers in the database buffer cache that are managed using a least recently used algorithm. As new data is read in, the oldest data is aged out.
Directive
With regards to an Oracle initialization parameter file, a directive is an entry in the file that has meaning to the program reading the file, rather than to the Oracle instance being started. For example, the IFILE directive is processed by Server Manager (or SQL*Plus), and is not passed on to the Oracle instance.
Dirty
In Oracle, a term often applied to a database buffer held in memory to signify that the buffer has been modified but that the modifications have not yet been written back out to disk.
Dirty Buffer
A buffer, in the database buffer cache, that contains a modified data block that has not been written to disk.
Dirty List
A list, maintained by the Oracle database software, that points to all the modified buffers in the database buffer cache that have not yet been written back out to the datafiles.
disk contention
The problem resulting when multiple processes are all trying to access data on the same disk, to the point where the disk becomes overloaded and cannot
respond to all the I/O requests in a timely fashion.
Disk Mirroring
The practice of linking two disk drives, usually with hardware, so that they operate as one. If one disk fails, the other disk continues to operate while the failed disk is replaced.
Data is protected, and users are not aware that anything out of the ordinary happened.
Mirroring is a form of RAID, and is referred to as RAID level 1. Mirroring is often combined with striping in order to balance the input/output
load across several disks.
Enterprise Manager
Oracle's flagship suite of database administration software. Enterprise Manager consists of a set up GUI-based tools used
to manage users, database objects, and security.
Enterprise Manager Console
A central screen used to monitor one or more Oracle databases, and from which you can launch any of the Enterprise Manager
applications.
Entry Point
When used in connection with an Oracle package, an entry point is a specific procedure or function you can call that is part of
that package.
Environment Variable
A variable maintained by the operating system. Environment.variables are sometimes used to convey information about your
environment to the Oracle software. For example, on UNIX.systems, the environment variable ORACLE_HOME points to the.top-level directory containing
the Oracle software.distribution.
Execution Plan
The plan that the Oracle software devises to best process a SQL statement.
foreign-key
A field, or a set of fields, in a table that reference a record in another table. Foreign keys are often used in parent-child
relationships. In an order-entry system, for example, line-item records would typically have one or more fields (the foreign-key) that identified
the parent order record.
formfeed character
A special character used to tell a printer to advance to a new page. Formfeed characters were a standard item in the days
before page description languages such as Postscript.
GETHIT Ratio
The GETHIT ratio tells you how often an SQL statement is.found already in memory, in the shared pool, and already.parsed. The
ratio is relative to 1, so a ratio of .90.indicates that 90% of SQL statements are found to already be.in the shared pool. Higher ratios indicate
better.performance than lower ones.
GETMISS Ratio
Tells you relatively how often Oracle has to go to the disk for data dictionary information as opposed to finding it already in
memory, in the data dictionary cache.
Grepping
The process, used under UNIX, of filtering the output of one command through the grep command in order to restrict output to specific items of interest.
GUI
An acronym for Graphical User Interface. A graphical user interface is characterized by windows, dropdown menus, buttons, and
the use of mouse to navigate.
Head of the Log
A pointer to the oldest redo log entry in the redo log buffer that has not yet been written to the redo log files. The log
writer process always writes from the head-end of the log.
Headers
When used in the context of a function or procedure, a header is the part of the program code that defines the number and types
(datatypes) of the inputs and outputs. Programmers often refer to these headers in order to ascertain how to correctly call a given procedure or
function.
hexadecimal
A base-16 numbering system often used to display an exact representation of data in memory. Hexadecimal numbering goes from
1-9, and then from A-F. The hexadecimal A is equivilant to the decimal value 10. After F, the next hexadecimal value is 10, which is equivilant to
the decimal value 16. Hexadecimal digits each represent exactly four binary bits, making hexadecimal a convenient alternative to writing long
strings of 1s and 0s.
I/O
An acronym for Input/Output. The term I/O is often used to refer to the amount data that is read from, or written to, the
database files on disk.
Index
In the context of a relational database, an index is a structure that allows you to quickly find records in a table based on
the contents of the specific table columns that have been indexed. An index on employee last name and first name fields, for example, would allow
you to retrieve an employee record by name. Indexes are an essential part of getting reasonable performance out of any relational database.
Initialization File
A text file containing a number of parameters that control the operation of an Oracle database. Initialization files are read
when an instance starts.
Initialization Parameter
An entry in a database's initialization file, or parameter file, that controls some aspect of the way the database instance
operates. For example, the SHARED_POOL parameter controls the size of the shared pool within the SGA.
Instance
A set of memory structures and background processes that operate against an Oracle database. Database users (programs that you
run) communicate with an Oracle instance (background processes), and the instance does the actual work of reading and writing data to and from the
database files. Using Oracle Parallel Server option, it is possible to have multiple instances simultaneously operating against a single
database.
Internal
A special Oracle user known as the internal user. All databases have an internal user, and it used to be quite common to
connect as internal in order to start or stop a database. Oracle now recommends connecting as SYSDBA or SYSOPER instead.
internal password
The password that you need to use when you issue a CONNECT INTERNAL command from Server Manager.
Keep Buffer Pool
A pool of buffers within the database buffer cache that is used to hold objects that are never to be flushed from memory.
Keyword
A word that is significant to a language or tool that you are using. SELECT, for example, is a SQL keyword.
Large Pool
An area of memory from which large allocations can be made.
Least Recently Used List
A list of pointers to database buffers that is maintained by Oracle in the SGA. The pointers in the LRU list are arranged in
order based on the time interval since a buffer was last accessed.
listener
A process that runs on a database server, and listens for incoming requests from clients that want to connect to databases on
that server.
Log Files
Another way of refering to redo log files.
Log Mining
The practice of reading a databases's redo log files in order to report out changes that have been made.
Log Switch
An event in which Oracle advances from writing one redo log group to writing the next.
LRU
An acronym for Least Recently Used.
LRU List
Least Recently Used List. A list of pointers to database buffers that is maintained by Oracle in the SGA. The pointers in the
LRU list are arranged in order based on the time interval since a buffer was last accessed.
LU6.2
A networking protocol used in IBM mainframe environments.
Mount Point
On a UNIX system, a mount point is the place in the directory structure where a disk is inserted. A mount point is basically a
directory path, such that the resulting destination is really the top-level directory of an entirely new disk.
Multi-threaded Server
An option that allows multiple user processes to share one server process. Normally with Oracle, each user connection has its
own dedicated server process. These server processes consume resources, and this arrangement becomes unwieldy when thousands of users connect to
the database. Because of this, Oracle has come up with a way to configure the server software that allows several user processes to share one
server process. Thus, 1000 users, all connected to Oracle at once, may only need 100 processes on the server.
Multiplex
To make many copies of something. In the Oracle world, multiplexing refers to the practice of maintaining several copies of
control files and redo log files.
Net8
Oracle's generic networking protocol, used to connect two databases to each other, or to connect client software to a
database server. Net8 insulates Oracle and client applications from the underlying network protocol being used.
Net8 service name
A Net8 service is a usually a database instance, but could be some other software that is accessible via Net8.
network adaptor
A Net8 component that adapts the Net8 software for a particular networking protocal. For example, the Net8 TCP/IP adaptor
allows you to run Net8 over a TCP/IP network.
OEM
Oracle's flagship suite of database administration software. Enterprise Manager consists of a set up GUI-based tools used
to manage users, database objects, and security.
OFA
OFA is an abbreviation for Optimal Flexible Architecture.
Optimal Flexible Architecture
The Optimal Flexible Archictecture is a set of guidelines from Oracle that provides suggestions for directory structures, file
placement, file naming conventions, and standard tablespaces that each database should have.
Oracle Base
The top-level Oracle directory on a given machine is referred to as the Oracle Base directory. If you are following OFA
guidance, all other Oracle directories will hang off of this one.
Oracle Change Management Pack
A set of Oracle Enterprise Manager applications that help the DBA plan and implement schema changes in an Oracle
environment.
Oracle Diagnostic Pack
A set of Oracle Enterprise Manager applications used to monitor and diagnose problems in an Oracle environment.
Oracle Enterprise Manager
Oracle's flagship suite of database administration software. Enterprise Manager consists of a set up GUI-based tools used
to manage users, database objects, and security.
Oracle Home
An Oracle Home is the top-level directory for a given release of the Oracle software. Typically, the release number is used for
the directory name. On a UNIX system running Oracle8i 8.1.5, the Oracle Home directory would be at $ORACLE_BASE/product/815.
Oracle Tuning Pack
A set of Oracle Enterprise Manager applications used for tuning an Oracle database environment.
Package
A package is a PL/SQL programming unit that binds together a number of related functions, procedures, and constants.
packs
With respect to Oracle Enterprise Manager, a pack is a set of related applications that delivers functionality covering one
aspect of database administration. The Oracle Tuning Pack, for example, consists of a set of applications that help a DBA tune an Oracle database
environment.
Page Footer
A set of lines that print at the bottom of each page of a SQL*Plus report.
Page Header
A set of lines that print at the top of each new page of a SQL*Plus report.
Parameter File
Another way of referring to the initialization file.
Parsing
The process of pulling apart a SQL statement and figuring out how best to execute it.
PGA
An acronym for Program Global Area.
ping
A utility used to verify TCP/IP connectivity between two nodes on a network.
Private SQL Area
Memory allocated to a user for the execution of SQL queries. The private SQL area contains user-specific values such as those
used for bind variables.
Private Synonym
An alternate name for a database object that allows you to reference that object without having to qualify the object name with
a schema name. There are two types of synonyms, public and private. Public synonyms apply to all users. Private synonyms apply to the user that
owns them.
Product User Profile
A table used as part of an application security scheme by SQL*Plus.
Production System
A system containing real data, and which is used to conduct real business, as opposed to a test system.
profile
A profile is a named collection of resource limits. Profiles can be assigned to users to prevent them from consuming inordinate
amounts of database resources.
Program Global Area
An area of memory set aside for the exclusive use of one process.
Public Synonym
An alternate name for a database object that allows you to reference that object without having to qualify the object name with
a schema name. There are two types of synonyms, public and private. Public synonyms apply to all users. Private synonyms apply to the user that
owns them.
quota
A limit on the amount of disk space that a user may use in a particular tablespace.
RAID
RAID = Redundant Array of Inexpensive Disks. RAID storage is commonly used for production systems in order to protect the
database files from being lost. RAID storage can be configured so that the loss of any single disk (and sometimes more than one) due to damage does
not cause the loss of any data files. Typically, a damaged disk can be removed and replaced by the system administrator while the system is
running, and no one outside of the operations staff will even be aware that a failure occurred.
Recovery
The process of reading entries from the redo log files (including the archived redo log files) and using that information to
replay changes that have been made to the database. Recovery is often used to bring a database up-to-date after it has been restored from a
backup.
Recycle Buffer Pool
A pool of buffers in the database buffer cache that should be held in memory for the minimum amount of time possible.
Redo Log
A record of changes made to a database. When the term redo log is used by itself, it usually refers generically to the entire
log of changes, not to any one file.
Redo Log Buffer
An area in the SGA that Oracle uses to hold redo log entries until they can be written to the log files.
Redo Log Entry
A redo log entry describes an atomic set of changes that have been made to one database block. It is not the same as a
transaction. Several log entries may go together to record one transaction. Redo log entries are often called redo log records, particularly after
they have been written to the log files.
Redo Log File
A file that contains part of a databases' redo log.
Redo Log Group
A group of redo log files that Oracle treats as a unit. Oracle writes the same information to each file, thus implementing a
form of mirroring using software rather than hardware.
Redo Log Member
One file in a group of redo log files.
Redo Log Switch
A redo log switch refers to the process of closing one redo log file and opening the next file in the seqeuence.
registry variable
A variable that is stored in the Windows Registry, and that must be edited using the regedit utility.
Restricted Session Mode
A mode in which the database is open, but normal users are not allowed to connect. Only users holding the restricted session
system privilege, usually only database administrators have this, can connect.
Rollback Segment
A database structure that Oracle uses to keep track of changes made by a transaction. The information is used to undo those
changes in the event that the transaction is rolled back. The information is also used to provide other database users with a consistent view of
the database. Other users do not see your changes until you have committed them. If someone retrieves a row that you have changed, and you
haven't committed that change yet, Oracle will send back the original version of that row using the information in the rollback segment.
schema
A schema is named collection of database objects. In Oracle, schemas are tightly linked to users--each user has one schema with
a name matching the user's name, and the term schema is sometimes used synonymously with user.
SELECT
SELECT is the SQL command used to retrieve data from a database.
Server Process
A process on the server that communicates with a user process, and which processes SQL statements submitted by that user
process.
service
service NT.A service under Windows NT is software that runs in the background, independently of any logged on user. ..service
Net8.A Net8 service is a usually a database instance, but could be some other software, that is accessible via Net8.
service handler
A Net8 related entity that runs in conjunction with the listener to handle connection requests for a database instance.
Session Information
Information, such as that contained in the private SQL area, that is specific to one Oracle database session. Under the
default, dedicated server configuration, session information is stored in the PGA for each session's dedicated server process. Under the
multi-threaded server configuration, session information is stored in the SGA.
SGA
An abbreviation for System Global Area.
Shared Pool
An area of shared memory that contains information related to the parsing and execution of SQL statements and PL/SQL
code.
SID
SID is an acronym for System Identifier. The system identifier is the name that identifies an Oracle instance.
Sort Area
An area of memory used for sorting data, often to satisfy the ORDER BY clause of an SQL SELECT statement.
SPX/IPX
A networking protocol used on Novel NetWare networks.
SQL
An acronym for Structured Query Language. It provides a set of commands that can be used to add data to a database, retrieve
that data, and update it. SQL, often pronounced sequel, is universally supported by relational database vendors.
SQL buffer
A memory area used by SQL*Plus to hold the most recently entered SQL statement or PL/SQL block.
SQL*Plus
An Oracle utility that can be used to submit ad-hoc SQL statements to the database. SQL*Plus can be used to generate simple
reports, run scripts, and even to extract data from a database into a text file.
sqlpath
The name of a UNIX environment variable, or on NT a registry entry, that defines a search path for SQL*Plus to use in looking
for a script file executed by a user.
Stack Space
With respect to the PGA, stack space is used to hold variables and arrays used by a process.
Storage Parameters
Values that control the way in which Oracle allocates disk space for a given table, view, or other database object. Storage
parameters allow you to control the size of an object's initial extent, it's subsequent extents, and the maximum number of extents.
Striping
Striping refers to the practice of taking small sections (or stripes) of several disks, linking them together, and treating
them as one large disk. This forces input and output to be distributed more evenly across the drives. Instead of one disk receiving a large amount
of I/O requests, striping could be used to spread the same amount of I/O across three disks, thus increasing performance.
Substitution Variable
Also called user variables, substitution variables are used in SQL*Plus scripts to mark a location where user-supplied text is
to be inserted.
Synonym
An alternate name for a database object that allows you to reference that object without having to qualify the object name with
a schema name. There are two types of synonyms, public and private. Public synonyms apply to all users. Private synonyms apply to the user that
owns them.
SYSDBA
A special type of privilege that allows the holder to administer an Oracle database. A user logged in as SYSDBA can do
anything, including starting, stopping, and recovering the database.
SYSOPER
A special type of privilege that allows the holder to perform several routine administrative tasks against an Oracle database.
A user logged in as SYSOPER is limited to starting the database, stopping the database, certain types of recovery, and a few other routine
chores.
System Global Area
A memory area that Oracle uses for a multitude of purposes such as the buffering data blocks, buffering redo log records,
holding SQL statements, and so forth. It's called shared because multiple Oracle process access it at the same time.
System Tablespace
The tablespace Oracle uses for the data dictionary. Oracle treats this differently from other tablespaces. It is the one
tablespace created by the CREATE DATABASE statement. Every database must have one, and it can never be taken offline.
tablespace
A logical container in which Oracle stores data. Database administrators map tablespaces onto one or more physical
datafiles.
Tail of the Log
A pointer to the most recent redo log entry. New redo log records are always added at the tail-end of the log.
TCP/IP
A networking protocal widely used in the UNIX world, and which happens to be the most commonly used protocol by clients that
need to connect to Oracle servers.
Temporary Segments
Temporary segments are those created by Oracle for the purpose of executing a single query. After the query results have been
determined, the segments are deleted. Temporary segments are most often used for sorting.
Thread
An independent execution path within a program.
three-tier architecture
An application architecture where you have an application that communicates to a middle-tier, often an application server,
which in turn communicates to a database server. Thus you have three tiers, or platforms, involved: the client, the application server, and the
database server.
Throughput
When used in reference to a disk drive, throughput is a measure of how much data the drive can physically pump back to the
application in a given period of time. A typical SCSI drive, for example, might have a sustained throughput of 17 megabytes/second. If all your
database files were on this one drive, your database throughput would be quite limited.
tnsping
A Net8 utility used to verify connectivity between a client and a remote listener.
Trigger
Code that is executed in response to a database event, or in response to a SQL statement issued against a table.
try it
Each time you click a glossary term, you'll see a window like this displaying the term and its definition. To see the
entire glossary, click "Show All Terms".
two-tier architecture
An application architecture where you have clients that communicate directly with a database server.
Usenet
Usenet is a networked collection of discussion groups that you can access via the internet.
User Variable
Also called substitution variables, user variables are used in SQL*Plus scripts to mark a location where user-supplied text is to be inserted.
X-Windows
A Graphical User Interface standard that is widely used in the UNIX world.