This page intentionally left blank Glossary A ACID Atomicity, Consistency, Isolation, and Durability. Four characteristics that a relational database must be able to maintain for transactions. ADDM Automatic Database Diagnostic Monitor. A tool that generates performance tuning reports based on snapshots in the AWR. ADR Automatic Diagnostic Repository. The default location for the alert log, trace files, and other information useful for fault finding. ADRCI The ADR command-line interface. AES Advanced Encryption Standard. A widely used data encryption method. AL16UTF16 A Unicode fixed-width two-byte character set, commonly specified for the NLS character set used for NVARCHAR2, NCHAR, and NCLOB data types. alias In Oracle Net, a pointer to a connect string. An alias must be resolved into the address of a listener and the name of a service or instance. ANSI American National Standards Institute. A U.S. body that defines a number of standards relevant to computing. 987 OCA/OCP Oracle Database 11g All-in-One Exam Guide 988 API Application programming interface. A defined method for manipulating data, typically implemented as a set of PL/SQL procedures in a package. ARBn Background processes that perform extent movement between disks in an Automatic Storage Management (ASM) disk group during the rebalancing process triggered by adding a disk to or removing a disk from the group. ASA Automatic Segment Advisor. An Oracle advisory tool that can recommend segments (tables or indexes) that are candidates for segment shrink. ASCII American Standard Code for Information Interchange. A standard (with many variations) for coding letters and other characters as bytes. ASH Active session history. A category of information in the AWR that records details of session activity. ASM Automatic Storage Management. A logical volume manager (LVM) provided with the Oracle database. ASMM Automatic Shared Memory Management. A technique for automating the allocation of memory to both the SGA and PGA structures. ASSM Automatic segment space management. The method of managing space within segments by use of bitmaps. attribute One element of a tuple (aka a column). AVG A function that divides the sum of a column or expression by the number of nonnull rows in a group. AWR Automatic Workload Repository. A set of tables in the SYSAUX tablespace, populated with tuning data gathered by the MMON process. B background process A process that is part of the instance: launched at startup. BFILE A large object data type that is stored as an operating system file. The value in the table column is a pointer to the file. bind variable A value passed from a user process to a SQL statement at statement execution time. BLOB Binary large object. A LOB data type for binary data, such as photographs and video clips. BLOBs do not undergo character set conversion when passed between a session’s user process and server process. block The units of storage into which datafiles are formatted. The size can be 2KB, 4KB, 8KB, 16KB, 32KB, or 64KB. Some platforms will not permit all these sizes. Glossary 989 BMR Block media recovery. An RMAN technique for restoration and recovery of individual data blocks, rather than complete datafiles. C Cartesian product Sometimes called a cross join. A mathematical term that refers to the set of data created by multiplying the rows from two or more tables together: every row is joined to every other row. CET Central European Time. A time zone used in much of Europe (though not Great Britain) that is one hour ahead of UTC, with daylight saving time in effect during the summer months. character set The encoding system for representing data within bytes. Different character sets can store different characters and may not be suitable for all languages. Unicode character sets can store any character. check constraint A simple rule enforced by the database that restricts the values that can be entered into a column. checkpoint An event that forces the DBWn to write all dirty buffers from the database buffer cache to the datafiles. CKPT The checkpoint process. The background process responsible for recording the current redo byte address—the point in time up to which the DBWn has written changed data blocks to disk—and for signaling checkpoints, which force DBWn to write all changed blocks to disk immediately. client-server architecture A processing paradigm where the application is divided into client software that interacts with the user and server software that interacts with the data. CLOB Character large object. A LOB data type for character data, such as text documents, stored in the database character set. cluster A hardware environment where more than one computer shares access to storage. A RAC database consists of several instances on several computers opening one database on the shared storage. cluster segment A segment that can contain one or more tables, denormalized into a single structure. COALESCE A function that returns the first nonnull value from its parameter list. If all its parameters are null, then a null value is returned. column An element of a row: tables are two-dimensional structures, divided horizontally into rows and vertically into columns. commit To make a change to data permanent. OCA/OCP Oracle Database 11g All-in-One Exam Guide 990 complete recovery Following a restore of damaged database files, a complete recovery applies all redo to bring the database up to date with no loss of data. connect identifier An Oracle Net alias. connect role A preseeded role retained only for backward compatibility. connect string The database connection details needed to establish a session: the address of the listener and the service or instance name. consistent backup A backup made while the database is closed. constraint A mechanism for enforcing rules on data: that a column value must be unique, or may only contain certain values. A primary key constraint specifies that the column must be both unique and not null. control file The file containing pointers to the rest of the database, critical sequence information, and the RMAN repository. CPU Central processing unit. The chip that provides the processing capability of a computer, such as an Intel Pentium or a Sun SPARC. CTWR Change Tracking Writer. The optional background process that records the addresses of changed blocks, to enable fast incremental backups. D data blocks The units into which datafiles are formatted, made up of one or more operating system blocks. data dictionary The tables and views owned by SYS in the SYSTEM tablespace that define the database and the objects within it. data dictionary views Views on the data dictionary tables that let the DBA investigate the state of the database. Data Guard A facility whereby a copy of the production database is created and updated (possibly in real time) with all changes applied to the production database. Data Pump A facility for transferring large amounts of data at high speed into, out of, or between databases. database buffer cache An area of memory in the SGA used for working on blocks copied from datafiles. database link A connection from one database to another, based on a username and password and a connect string. Database Replay An Oracle feature that can help assess the performance impact of a workload captured from one system and replayed on another. Glossary 991 datafile The disk-based structure for storing data. DBA Database administrator. The person responsible for creating and managing Oracle databases—this could be you. DBA role A preseeded role in the database provided for backward compatibility that includes all the privileges needed to manage a database, except that needed to start up or shut down. DBCA The Database Configuration Assistant. A GUI tool for creating, modifying, and dropping instances and databases. DBID Database identifier. A unique number for every database, visible in the DBID column of the V$DATABASE dynamic performance view. DBMS Database management system, often used interchangeably with RDBMS. DBWn or DBWR The Database Writer. The background process responsible for writing changed blocks from the database buffer cache to the datafiles. An instance may have up to 20 database writer processes, DBW0 through DBWj. DDL Data Definition Language. The subset of SQL commands that change object definitions within the data dictionary: CREATE, ALTER, DROP, and TRUNCATE. deadlock A situation where two sessions block each other, such that neither can do anything. Deadlocks are detected and resolved automatically by the DIA0 background process. DECODE A function that implements if-then-else conditional logic by testing two terms for equality and returning the third term if they are equal or, optionally, returning some other term if they are not. DHCP Dynamic Host Configuration Protocol. The standard for configuring the network characteristics of a computer, such as its IP address, in a changing environment where computers may be moved from one location to another. DIA0 The diagnosability process that detects hang and deadlock situations. DIAG The diagnosability process that generates diagnostic dumps. direct path A method of I/O on datafiles that bypasses the database buffer cache. directory object An Oracle directory: a object within the database that points to an operating system directory. dirty buffer A buffer in the database buffer cache that contains a copy of a data block that has been updated in memory and not yet written back to the datafile. DMnn Data Pump Master process. The process that controls a Data Pump job—one will be launched for each job that is running. OCA/OCP Oracle Database 11g All-in-One Exam Guide 992 DML Data Manipulation Language. The subset of SQL commands that change data within the database: INSERT, UPDATE, DELETE, and MERGE. DNS Domain Name Service. The TCP mechanism for resolving network names into IP addresses. domain The set of values an attribute is allowed to take. Terminology: tables have rows; rows have columns with values. Or: relations have tuples; tuples have attributes with values taken from their domain. DSS Decision Support System. A database, such as a data warehouse, optimized for running queries as opposed to OLTP work. DWnn Data Pump Worker process. There will be one or more of these launched for each Data Pump job that is running. E easy connect A method of establishing a session against a database by specifying the address on the listener and the service name, without using an Oracle Net alias. EBCDIC Extended Binary Coded Decimal Interchange Code. A standard developed by IBM for coding letters and other characters in bytes. environment variable A variable set in the operating system shell that can be used by application software and by shell scripts. equijoin A join condition using an equality operator. F fact table The central table in a star schema, with columns for values relevant to the row and columns used as foreign keys to the dimension tables. FGA Fine-grained auditing. A facility for tracking user access to data, based on the rows that are seen or manipulated. flash recovery area A default location for all recovery-related files. Flashback Data Archive A database container object that retains historical data for one or more database objects for a specified retention period. Flashback Database A flashback feature that recovers the entire database to a prior point in time using Flashback Database logs. Flashback Database logs Changed database blocks that are stored in the flash recovery area and used for Flashback Database. Flashback Drop A flashback feature that makes it easy to recover dropped tables if they are still in the recycle bin. Glossary 993 Flashback Query A flashback feature that enables you to view table rows at a prior point in time. Flashback Table A Flashback Query that recovers a single table and its associated objects to a prior point in time. full backup A backup containing all blocks of the files backed up, not only those blocks changed since the last backup. G GMT Greenwich Mean Time. Now referred to as UTC, this is the time zone of the meridian through Greenwich Observatory in London. grid computing An architecture where the delivery of a service to end users is not tied to certain server resources but can be provided from anywhere in a pool of resources. GROUP BY A clause that specifies the grouping attribute rows must have in common for them to be clustered together. GUI Graphical user interface. A layer of an application that lets users work with the application through a graphical terminal, such as a PC with a mouse. H HTTP Hypertext Transfer Protocol. The protocol that enables the World Wide Web (both invented at the European Organization for Nuclear Research in 1989)—this is a layered protocol that runs over TCP/IP. HWM High water mark. This is the last block of a segment that has ever been used—blocks above this are part of the segment but are not yet formatted for use. I I/O Input/output. The activity of reading from or writing to disks—often the slowest point of a data processing operation. image copy An RMAN copy of a file. inconsistent backup A backup made while the database was open. incremental backup A backup containing only blocks that have been changed since the last backup was made. INITCAP A function that accepts a string of characters and returns each word in title case. inner join When equijoins and nonequijoins are performed, rows from the source and target tables are matched. These are referred to as inner joins. OCA/OCP Oracle Database 11g All-in-One Exam Guide 994 instance recovery The automatic repair of damage caused by a disorderly shutdown of the database. INSTR A function that returns the positional location of the nth occurrence of a specified string of characters in a source string. IOT Index-organized table. A table type where the rows are stored in the leaf blocks of an index segment. IP Internet Protocol. Together with the Transmission Control Protocol, TCP/IP: the de facto standard communication protocol used for client/server communication over a network. IPC Inter-Process Communications protocol. The platform-specific protocol, provided by your OS vendor, used by processes running on the same machine to communicate with each other. ISO International Organization for Standardization. A group that defines many standards, including SQL. J J2EE Java 2 Enterprise Edition. The standard for developing Java applications. JOIN . . . ON A clause that allows the explicit specification of join columns regardless of their column names. This provides a flexible joining format. JOIN . . . USING A syntax that allows a natural join to be formed on specific columns with shared names. joining Involves linking two or more tables based on common attributes. Joining allows data to be stored in third normal form in discrete tables, instead of in one large table. JVM Java Virtual Machine. The runtime environment needed for running code written in Java. Oracle provides a JVM within the database, and there will be one provided by your operating system. L large pool A memory structure within the SGA used by certain processes: principally shared server processes and parallel execution servers. LAST_DAY A function used to obtain the last day in a month given any valid date item. LDAP Lightweight Directory Access Protocol. The TCP implementation of the X25 directory standard, used by the Oracle Internet Directory for name resolution, Glossary 995 security, and authentication. LDAP is also used by other software vendors, including Microsoft and IBM. LENGTH A function that computes the number of characters in a string, including spaces and special characters. LGWR The Log Writer. The background process responsible for flushing change vectors from the log buffer in memory to the online redo log files on disk. library cache A memory structure within the shared pool, used for caching SQL statements parsed into their executable form. listener The server-side process that listens for database connection requests from user processes and launches server processes to establish sessions. LOB Large object. A data structure that is too large to store within a table. LOBs (Oracle supports several types) are defined as columns of a table but physically are stored in a separate segment. log switch The action of closing one online logfile group and opening another: triggered by the LGWR process filling the first group. LRU Least recently used. LRU lists are used to manage access to data structures, using algorithms that ensure that the data that has not been accessed for the longest time is the data that will be overwritten. LVM Logical Volume Manager. A layer of software that abstracts the physical storage within your computer from the logical storage visible to an application. M MMAN The Memory Manager background process, which monitors and reassigns memory allocations in the SGA for automatically tunable SGA components. MML Media Management Layer. Software that lets RMAN make use of automated tape libraries and other SBT devices. MMNL Manageability Monitor Light. The background process responsible for flushing ASH data to the AWR, if MMON is not doing this with the necessary frequency. MMON The Manageability Monitor is a background process that is responsible for gathering performance monitoring information and raising alerts. MOD The modulus operation, a function that returns the remainder of a division operation. MONTHS_BETWEEN A function that computes the number of months between two given date parameters and is based on a 31-day month. . datafiles. database link A connection from one database to another, based on a username and password and a connect string. Database Replay An Oracle feature that can help assess the performance. or manipulated. flash recovery area A default location for all recovery-related files. Flashback Data Archive A database container object that retains historical data for one or more database. for a specified retention period. Flashback Database A flashback feature that recovers the entire database to a prior point in time using Flashback Database logs. Flashback Database logs Changed