12c Release 2 (18.104.22.168) / 1 March 2017
|Written in||Assembly language, C, C++|
It is the world's most popular database for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database workloads. The latest generation, Oracle Database 12c Release 2 (commonly referred to as 12.2), is available on-prem, on-Cloud, or in a hybrid-Cloud environment. 12.2 may also be deployed on Oracle Engineered Systems (e.g. Exadata) on-prem, on Oracle (public) Cloud or (private) Cloud at Customer (e.g. Exadata Cloud at Customer). At Openworld 2017 in San Francisco, Executive Chairman of the Board and CTO, Larry Ellison announced the next database generation, Oracle Autonomous Database.
Larry Ellison and his two friends and former co-workers, Bob Miner and Ed Oates, started a consultancy called Software Development Laboratories (SDL) in 1977. SDL developed the original version of the Oracle software. The name Oracle comes from the code-name of a CIA-funded project Ellison had worked on while formerly employed by Ampex.
Oracle products follow a custom release-numbering and -naming convention. The "c" in the current release, Oracle Database 12c, stands for "Cloud". Previous releases (e.g. Oracle Database 10g and Oracle9i Database) have used suffixes of "g" and "i" which stand for "Grid" and "Internet" respectively. Prior to the release of Oracle8i Database, no suffixes featured in Oracle Database naming conventions. Note that there was no v1 of Oracle Database, as Larry Ellison, "knew no one would want to buy version 1". Oracle's RDBMS release numbering has used the following codes:
|Oracle v2||2.3||1979||First commercially available SQL-based RDBMS|
|Oracle v3||3.1.3||1983||Concurrency control, data distribution, and scalability|
|Oracle v4||22.214.171.124||1984||126.96.36.199||Multiversion read consistency|
|Oracle v5||5.0.22 (5.1.17)||1985||5.1.22||Support for client/server computing and distributed database systems|
|Oracle v6||6.0.17||1988||6.0.37||Row-level locking, scalability, online backup and recovery, PL/SQL|
|Oracle 6.2||6.2.0||Oracle Parallel Server|
|Oracle7||7.0.12||June 1992||PL/SQL stored procedures, Triggers, Distributed 2-phase commit, Shared Cursors, Cost Based Optimizer|
|Oracle 7.1||7.1.0||Parallel SQL Execution|
|Oracle 7.2||7.2.0||June 1992||Shared Server, XA Transactions, Transparent Application Failover|
|Orale 7.3||7.3.0||June 1992||7.3.4||February 1996||Object-relational database|
|Oracle8 Database||8.0.3||June 1997||8.0.6||Recovery Manager, Partitioning|
|Oracle8i Database||188.8.131.52||1998||184.108.40.206||August 2000||Native internet protocols and Java, Virtual Private Database|
|Oracle9i Database||220.127.116.11||2001||18.104.22.168||December 2003||Oracle Real Application Clusters (RAC), Oracle XML DB|
|Oracle9i Database Release 2||22.214.171.124||126.96.36.199||April 2007||Advanced Queuing, Data Mining, Streams, Logical Standby|
|Oracle Database 10g Release 1||10.1.0.2||2003||10.1.0.5||February 2006||Automated Database Management, Automatic Database Diagnostic Monitor, Grid infrastructure, Oracle ASM, Flashback Database|
|Oracle Database 10g Release 2||10.2.0.1||July 2005 ||10.2.0.5||April 2010||Real Application Testing, Database Vault, Online Indexing, Advanced Compression, Data Guard Fast-Start Failover, Transparent Data Encryption|
|Oracle Database 11g Release 1||188.8.131.52||September 2007||184.108.40.206||September 2008||Active Data Guard, Secure Files, Exadata|
|Oracle Database 11g Release 2||220.127.116.11||September 2009 ||18.104.22.168||August 2013||Edition Based Redefinition, Data Redaction, Hybrid Columnar Compression, Cluster File System, Golden Gate Replication, Database Appliance|
|Oracle Database 12c Release 1||22.214.171.124||July 2013 ||126.96.36.199||July 2014||Multitenant architecture, In-Memory Column Store, Native JSON, SQL Pattern Matching, Database Cloud Service|
|Oracle Database 12c Release 2||188.8.131.52||September 2016 (cloud)
March 2017 (on-prem)
|Native Sharding, Zero Data Loss Recovery Appliance, Exadata Cloud Service, Cloud at Customer|
|Oracle Database 18c||18.1.0||February 2018||Polymorphic Table Functions, MDX Query support|
The Oracle Database Administrators Guide includes a brief history on some of the key innovations introduced with each major release of Oracle Database.
Oracle Corporation releases Critical Patch Updates (CPUs) or Security Patch Updates (SPUs) and Security Alerts to close security holes that could be used for data theft. Critical Patch Updates (CPUs) and Security Alerts come out quarterly on the Tuesday closest to 17th day of the month.
Oracle Database may be licensed and deployed on-premises on a choice of platforms including Oracle Engineered Systems, and on-Cloud with a choice of services running on general purpose hardware or Exadata. The various editions and Cloud services provide different levels of database functionality for difference use cases (e.g. dev/test, departmental and non-critical apps, mission-critical workloads) with different levels of performance, availability, etc. service levels.
Oracle Corporation provides a wide-range of database cloud services on its Oracle Cloud platform that are designed for different database use cases; from test/dev deployments to small and medium sized workloads to large mission-critical workloads. Oracle Database Cloud Services are available on a choice of general purpose hardware and Exadata engineered systems, in either virtual machines environments or 'bare metal' infrastructure (now known as Oracle Cloud Infrastructure).
As of 2017:, the latest Oracle Database version (184.108.40.206) comes in three editions for on-premises deployments
Oracle Corporation also makes the following edition available:
Up to (and including) Oracle Database 12c release 220.127.116.11, Oracle also offered the following:
Oracle Corporation discontinued SE and SE1 with the 18.104.22.168 release, and stopped offering new licenses for these editions on December 1, 2015.
Oracle Database 12c is supported on the following OS and architecture combinations:
In 2008, Oracle Corporation announced the availability of Oracle Exadata Database Machine (V1), the first generation of Engineered Systems specifically designed for Oracle Database workloads.
In 2011, Oracle Corporation announced the availability of Oracle Database Appliance, a pre-built, pre-tuned, highly available clustered database server built using two SunFire X86 servers and direct attached storage.
Some Oracle Enterprise Edition databases running on certain Oracle-supplied hardware can use Hybrid Columnar Compression for more efficient storage.
The Oracle Database offers a wide range of options and features in the areas of Availability, Scalability, Analytics, Performance, Security, Management, Developers and Integration. These aim to enhance and complement existing database functionality to meet customer-specific requirements. All Database Options are only available for Enterprise Edition and offered for an extra cost. An exception to these two rules is Oracle Real Application Clusters option, which comes included with Oracle Database 12c Standard Edition 2 at no additional cost.
Apart from the clearly defined database options, Oracle databases may include many semi-autonomous software sub-systems, which Oracle Corporation sometimes refers to as "features" in a sense subtly different from the normal use of the word. For example, Oracle Data Guard counts officially as a feature, but the command-stack within SQL*Plus, though a usability feature, does not appear in the list of "features" in Oracle's list.[original research?] Such "features" may include (for example):
Oracle database provides a long list of supported data models that can be used and managed inside Oracle database:
Oracle Corporation classifies as "utilities" bundled software supporting data transfer, data maintenance and database administration.
Utilities included in Oracle database distributions include:
The most popular application development tool that ships with Oracle Database is Oracle Application Express (APEX), a browser-based tool that allows developers to build responsive, database-driven applications, leveraging their SQL and PL/SQL skills.
Oracle SQL Developer, a free graphical tool for database development, allows developers to browse database objects, to run SQL statements and SQL scripts, and to edit and debug PL/SQL statements. It incorporates standard and customized reporting.
Oracle Database can be accessed from many programming languages and environments. These include:
Java based languages like Scala can use JDBC to access Oracle Database.
PL/SQL routines within Oracle databases can access external routines registered in operating-system shared libraries. The DBMS_SCHEDULER package can invoke external scripts at the operating-system level from PL/SQL.
The Oracle RDBMS has had a reputation among novice users as difficult to install on Linux systems. Oracle Corporation has packaged recent versions for several popular Linux distributions in an attempt to minimize installation challenges beyond the level of technical expertise required to preinstall a database server.
Users who have Oracle support contracts can use Oracle's "My Oracle Support" or "MOS" web site - known as "MetaLink" until a re-branding exercise completed in October 2010. The support site provides users of Oracle Corporation products with a repository of reported problems, diagnostic scripts and solutions. It also integrates with the provision of support tools, patches and upgrades.
The Remote Diagnostic Agent or RDA can operate as a command-line diagnostic tool executing a script. The data captured provides an overview of the Oracle Database environment intended for diagnostic and trouble-shooting. Within RDA, the HCVE (Health Check Validation Engine) can verify and isolate host system environmental issues that may affect the performance of Oracle software.
Oracle Corporation also endorses certain practices and conventions as enhancing the use of its database products. These include:
A large number of User Groups for Oracle Database administrators, developers and users has been established on geographical/region, industry and product basis, including:
The Oracle User Group communities also host regular events for customers/users to share their experiences and knowledge.
In the market for relational databases, Oracle Database competes against commercial products such as IBM's DB2 UDB and Microsoft SQL Server. Oracle and IBM tend to battle for the mid-range database market on UNIX and Linux platforms, while Microsoft dominates the mid-range database market on Microsoft Windows platforms. However, since they share many of the same customers, Oracle and IBM tend to support each other's products in many middleware and application categories (for example: WebSphere, PeopleSoft, and Siebel Systems CRM), and IBM's hardware divisions work closely with Oracle on performance-optimizing server-technologies (for example, Linux on z Systems). Niche commercial competitors include Teradata (in data warehousing and business intelligence), Software AG's ADABAS, Sybase, and IBM's Informix, among many others.
Increasingly, the Oracle database products compete against such open-source software relational database systems as PostgreSQL, MongoDB, and Couchbase. Oracle acquired Innobase, supplier of the InnoDB codebase to MySQL, in part to compete better against open source alternatives, and acquired Sun Microsystems, owner of MySQL, in 2010. Database products licensed as open source are, by the legal terms of the Open Source Definition, free to distribute and free of royalty or other licensing fees.
An Oracle database system--identified by an alphanumeric system identifier or SID--comprises at least one instance of the application, along with data storage. An instance--identified persistently by an instantiation number (or activation id: SYS.V_$DATABASE.ACTIVATION#)--comprises a set of operating-system processes and memory-structures that interact with the storage. Typical processes include PMON (the process monitor) and SMON (the system monitor). Oracle documentation can refer to an active database instance as a "shared memory realm".
Users of Oracle databases refer to the server-side memory-structure as the SGA (System Global Area). The SGA typically holds cache information such as data-buffers, SQL commands, and user information. In addition to storage, the database consists of online redo logs (or logs), which hold transactional history. Processes can in turn archive the online redo logs into archive logs (offline redo logs), which provide the basis for data recovery and for the physical-standby forms of data replication using Oracle Data Guard.
The Oracle RAC (Real Application Clusters) option uses multiple instances attached to a central storage array. In version 10g, grid computing introduced shared resources where an instance can use CPU resources from another node in the grid. The advantage of Oracle RAC is that the resources on both nodes are used by the database, and each node uses its own memory and CPU. Information is shared between nodes through the interconnect--the virtual private network.
The Oracle DBMS can store and execute stored procedures and functions within itself. PL/SQL (Oracle Corporation's proprietary procedural extension to SQL), or the object-oriented language Java can invoke such code objects and/or provide the programming structures for writing them.
The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files ("datafiles"). Tablespaces can contain various types of memory segments, such as Data Segments, Index Segments, etc. Segments in turn comprise one or more extents. Extents comprise groups of contiguous data blocks. Data blocks form the basic units of data storage.
A DBA can impose maximum quotas on storage per user within each tablespace.
The partitioning feature was introduced in Oracle 8. This allows the partitioning of tables based on different set of keys. Specific partitions can then be added or dropped to help manage large data sets.
Oracle database management tracks its computer data storage with the help of information stored in the
SYSTEM tablespace. The
SYSTEM tablespace contains the data dictionary, indexes and clusters. A data dictionary consists of a special collection of tables that contains information about all user-objects in the database. Since version 8i, the Oracle RDBMS also supports "locally managed" tablespaces that store space management information in bitmaps in their own headers rather than in the
SYSTEM tablespace (as happens with the default "dictionary-managed" tablespaces). Version 10g and later introduced the
SYSAUX tablespace, which contains some of the tables formerly stored in the
SYSTEM tablespace, along with objects for other tools such as OEM, which previously required its own tablespace.
Disk files primarily represent one of the following structures:
Most Oracle database installations come with a default schema called
SCOTT. After the installation process sets up sample tables, the user logs into the database with the username
scott and the password
tiger. The name of the
SCOTT schema originated with Bruce Scott, one of the first employees at Oracle (then Software Development Laboratories), who had a cat named Tiger.
Oracle Corporation now de-emphasizes the
SCOTT schema, as it uses few features of more recent Oracle releases. Most recent examples supplied by Oracle Corporation reference the default HR or OE schemas.
SYS(essential core database structures and utilities)
SYSTEM(additional core database structures and utilities, and privileged account)
OUTLN(used to store metadata for stored outlines for stable query-optimizer execution plans.)
SH(expanded sample schemas containing more data and structures than the older
Each Oracle instance allocates itself an SGA when it starts and de-allocates it at shut-down time. The information in the SGA consists of the following elements, each of which has a fixed size, established at instance startup:
Every Oracle database has one or more physical datafiles, which contain all the database data. The data of logical database structures, such as tables and indexes, is physically stored in the datafiles allocated for a database.
Datafiles have the following characteristics:
Data in a datafile is read, as needed, during normal database operation and stored in the memory cache of Oracle Database. For example, if a user wants to access some data in a table of a database, and if the requested information is not already in the memory cache for the database, then it is read from the appropriate datafiles and stored in memory.
Modified or new data is not necessarily written to a datafile immediately. To reduce the amount of disk access and to increase performance, data is pooled in memory and written to the appropriate datafiles all at once.
When you start the instance by using Enterprise Manager or SQL*Plus, the amount of memory allocated for the SGA is displayed.<link>
The library cache stores shared SQL, caching the parse tree and the execution plan for every unique SQL statement. If multiple applications issue the same SQL statement, each application can access the shared SQL area. This reduces the amount of memory needed and reduces the processing-time used for parsing and execution planning.
Oracle databases store information here about the logical and physical structure of the database. The data dictionary contains information such as:
The Oracle instance frequently accesses the data dictionary to parse SQL statements. Oracle operation depends on ready access to the data dictionary--performance bottlenecks in the data dictionary affect all Oracle users. Because of this, database administrators must make sure that the data dictionary cache has sufficient capacity to cache this data. Without enough memory for the data-dictionary cache, users see a severe performance degradation. Allocating sufficient memory to the shared pool where the data dictionary cache resides precludes this particular performance problem.
The Program Global Area or PGA memory-area of an Oracle instance contains data and control-information for Oracle's server-processes or background process. Every server or background process has its own PGA, the total of PGA elements is called Instance PGA.
The size and content of the PGA depends on the Oracle-server options installed. This area consists of the following components:
DBAs can monitor PGA usage via the system view.
The dynamic performance views (also known as "fixed views") within an Oracle database present information from virtual tables (X$ tables) built on the basis of database memory. Database users can access the V$ views (named after the prefix of their synonyms) to obtain information on database structures and performance.
The Oracle RDBMS typically relies on a group of processes running simultaneously in the background and interacting to monitor and expedite database operations. Typical operating environments might include - temporarily or permanently - some of the following individual processes (shown along with their abbreviated nomenclature):
Oracle Database terminology distinguishes different computer-science terms in describing how end-users interact with the database:
Each session within an instance has a session identifier - a session ID or "SID" (distinct from the Oracle system-identifier SID), and may also have an associated SPID (operating-system process identifier).
Oracle databases control simultaneous access to data resources with locks (alternatively documented as "enqueues"). The databases also use "latches" - low-level serialization mechanisms to protect shared data structures in the System Global Area.
Oracle locks fall into three categories:
Note: over the course of multiple releases Oracle has reduced the number of instances where an exclusive DDL lock is required when making changes to schema objects.
Non-blocking ddl's added as of 11.2
Non-blocking ddl's added to the list in 12.1
Non-blocking ddl's added to the list in 12.2
Non-blocking ddl's added to the list in 18.1
Database administrators control many of the tunable variations in an Oracle instance by means of values in a parameter file. This file in its ASCII default form ("pfile") normally has a name of the format
init<SID-name>.ora. The default binary equivalent server parameter file ("spfile") (dynamically reconfigurable to some extent) defaults to the format
spfile<SID-name>.ora. Within an SQL-based environment, the views
V$SPPARAMETER give access to reading parameter values.
K: Kernel KA: Kernel Access KC: Kernel Cache KCB: Kernel Cache Buffer KCBW: Kernel Cache Buffer Wait KCC: Kernel Cache Control file KCCB: Kernel Cache Control file Backup KCCCF: Kernel Cache Copy Flash recovery area KCCDC: Kernel cache Control file Copy KCP: Kernel Cache transPortable tablespace KCR: Kernel Cache Redo KCT: Kernel Cache insTance KD: Kernel Data KG: Kernel Generic KGL: Kernel Generic library cache KGLJ: Kernel Generic library cache Java KJ: Kernel Locking KK: Kernel Compilation KQ: Kernel Query KS: Kernel Service(s) KSB: Kernel Service Background KSM: Kernel Service Memory KSR: Kernel Service Reliable message KSU: Kernel Service User KSUSE: Kernel Service User SEssion KSUSECON: Kernel Service User SEssion CONnection KSUSEH: Kernel Service User SEssion History KT: Kernel Transaction(s) KTU: Kernel Transaction Undo KX: Kernel Execution KXS: Kernel eXecution Sql KZ: Kernel Security K2: Kernel Distributed Transactions
The "Scheduler" (DBMS_SCHEDULER package, available from Oracle 10g onwards) and the "Job" subsystems (DBMS_JOB package) permit the automation of predictable processing.
Oracle Resource Manager aims to allocate CPU resources between users and groups of users when such resources become scarce. As of Oracle Release 10.2, Database Resource Manager operates in Enterprise Edition.
Oracle Corporation has stated in product announcements that manageability for DBAs improved from Oracle9i to 10g. Lungu and V?tuiu (2008) assessed relative manageability by performing common DBA tasks and measuring timings.  They performed their tests on a single Pentium CPU (1.7 GHz) with 512 MB RAM, running Windows Server 2000. From Oracle9i to 10g, installation improved 36%, day-to-day administration 63%, backup and recovery 63%, and performance diagnostics and tuning 74%, for a weighted total improvement of 56%. The researchers concluded that "Oracle10g represents a giant step forward from Oracle9i in making the database easier to use and manage".
This section needs expansion. You can help by adding to it. (September 2016)
Oracle Database software comes in 63 language-versions (including regional variations such as British English and American English). Variations between versions cover the names of days and months, abbreviations, time-symbols (such as A.M. and A.D.), and sorting.
Oracle Corporation has translated Oracle Database error-messages into Arabic, Catalan, Chinese, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Romanian, Russian, Slovak, Spanish, Swedish, Thai and Turkish.
Oracle Corporation provides database developers with tools and mechanisms for producing internationalized database applications: referred to internally as "Globalization".
You should not get confused between Critical Patch Update (CPU) and Security Patch Update (SPU) as CPU terminology has been changed to SPU from October 2012.
Oracle Database Hybrid Columnar Compression is included at no extra cost with the Sun ZFS Storage Appliance and Pillar Axiom Storage System [...] Oracle's Hybrid Columnar Compression technology [...] uses a combination of both row and columnar methods for storing data. This approach [...] achieves the compression benefits of columnar storage, while avoiding the performance shortfalls of a pure columnar format.
The Oracle Spatial and Graph option for Oracle Database 12c includes advanced features for spatial data and analysis; physical, network, and social graph applications; and a foundation to help location-enable business applications.
A majority of the functionality of spatial indexes and spatial operators is part of Oracle Locator (included in all editions of the Oracle Database).
The Database Resource Manager (DRM) was first introduced in Oracle 8i [...] to place limits on the amount of computer resources that can be used [...]
The Expression Filter feature can be installed on an Oracle 10g Standard or Enterprise Edition database. It is provided as a set of PL/SQL packages, a Java package, a set of dictionary tables, catalog views. All these objects are created in a dedicated schema named EXFSYS.
In the fast-start parallel rollback method, the background process SMON [...] rolls back a set of transactions in parallel [...] This feature is particularly useful when a system has transactions that run a long time before committing [...]
...the standard audit (available in all versions) and the fine-grained audit (available in Oracle 9i and up ...
The core of Oracle's database virtual federation strategy is Heterogeneous Services (HS). Heterogeneous Services provides [sic] transparent and generic gateway technology to connect to non-Oracle systems. Heterogeneous Services is an integrated component of the database. Therefore, it can exploit all the capabilities of the Oracle database including PL/SQL and Oracle SQL extensions.
The Oracle Data Provider for .NET (ODP.NET) features optimized ADO.NET data access to the Oracle database.
SQLcl is a new Java-based command-line interface for Oracle Database. [...] The new take on SQL*Plus, SQLcl, is based on the script engine in Oracle SQL Developer and is attached to a Java-based command-line interface.
The UCP is a Java-basd connection pool that supports JDBC, the Lightweight Directory Access Protocol (LDAP) and Java EE Connector Architecture (JCA) connection types from any middle tier.
Oracle's Virtual Private Database (VPD) [...] is a practically implemented model for fine-grained access control wherein one or more security policies are attached to each table and view in the database. These policies are sets of functions coded in PL/SQL, C or Java. A user query that accesses a table or view having a security policy, is dynamically and transparently modified by appending a predicate. This predicate is returned by the policy function for the relation/view and is a function of the user who has fired the query. A secure application context is created for each user at log in.
Oracle Application Express is a no-cost option of the Oracle database.
[...] Oracle provides the Workspace Manager, a feature you can use to version-enable tables, so different users can maintain different versions of the data.
The WMSYS account owns the schema used to store metadata information for the Oracle Workspace Manager. Workspace Manager is a tool used to manage multiple versions of data within the same database.
Oracle XML DB is a high-performance, native XML storage and retrieval technology that is delivered as a part of all versions of Oracle Database.
The Oracle XML Database (also known as XDB) furnishes a native XMLType data type for managing XML documents directly in the database.
Oracle Multimedia is a feature that enables Oracle Database to store, manage, and retrieve multimedia data in an integrated manner with other enterprise information.
Oracle Utilities [...] This chapter describes Oracle database utilities for data transfer, data maintenance, and database administration.
The oradebug utility can be used to enable and disable tracing for a session.
Oracle Corporation has started a drive toward wizard-driven environments with a view to enabling non-programmers to produce simple data-driven applications.
Oracle REST Data Services is a Java EE-based alternative for Oracle HTTP Server and mod_plsql. The Java EE implementation offers increased functionality including a command line based configuration, enhanced security, file caching, and RESTful web services.
[...] Oracle REST Data Services (ORDS) [...] provides a REST-based interface to data in relational tables.
The Database Upgrade Assistant (DBUA) is a GUI tool that guides you through the various steps in the upgrade process and configures the database for the target release.
The DBUA is a GUI that is designed for upgrading your Oracle database [...]
Native compilation provides a speed increase ranging from two to ten times the speed of the bytecode interpretation.
OPatch is a collection of Perl scripts and Java classes providing the capability to apply and roll back interim (one-off) patches to an Oracle database environment.
[...] fast Oracle SQL tuning with SQLTXPLAIN, or SQLT as it is typically called [...]
Oracle Live SQL exists to provide the Oracle database community with an easy online way to test and share SQL and PL/SQL application development concepts.
An external program must be executed as a shared library to be accessed in PL/SQL. [...] The shared libraries may include multiple programs, which can be invoked as external programs.
If users have the CREATE LIBRARY, or any of the other library privileges. then they have the ability to run arbitrary code through external procedures.
Search Oracle's My Oracle Support (MOS) web site at http://support.oracle.com.
Run the Install checklist for Oracle 10.2.0 (Metalink Note 250262.1: RDA 4 - Health Check / Validation Engine Guide): The Health Check Validation Engine (HCVE) rule set for Oracle Database 10g R2 (10.2.0) PreInstall (AIX) is described in: Oracle.com
Oracle products are currently licensed using two different licensing models: Per Named User. [...] Per Processor [...]
The SID automatically defaults to the database name portion of the global database name (sales in the example sales.us.example.com) until you reach eight characters or enter a period. You can accept or change the default value.
The set of programs also lets you start a database instance. They allocate a shared memory realm where other programs process SQL statements. This shared memory realm is the active database instance.
Oracle databases are logically divided into one or more tablespaces. An Oracle tablespace is a logical entity that contains the physical datafiles.
You can use tablespaces to achieve the following goals: [...] Assign a quota (space allowance or limit) to a database user [...]
In 10g, Oracle introduced a new kind of storage for its database product. Automatic Storage Management (ASM) is a logical volume manager that takes physical disk partitions and manages their contents [...] Until ASM, there were only two choices: file system storage and raw disk storage.
X$ tables are fixed tables created in memory at database startup [...] V$ views are created on one or more X$ tables
V$INDEXED_FIXED_COLUMN displays the columns in dynamic performance tables that are indexed (X$ tables).[dead link]
The worker process is named <instance>_DWnn_<pid>. It is the process that actually performs the heavy-duty work of loading and unloading data. The master process (DMnn) creates the worker process.
Data Guard Monitor (DMON)[:] This Broker-controller process is the main Broker process and is responsible for coordinating all Broker actions as well as maintaining the Broker configuration files.
The job queue is handled by the job queue coordinator process CJQ0 and job queue slave processes (JNNN).
The optional net_timeout parameter to the log_archive_dest_n parameter allows the DB As to specify the number of seconds the log writer process (LGWR) waits for a response from the logwriter network server (LNS) before terminating the process.
MMON Memory Monitor process is associated with the Automatic Workload Repository new features used for automatic problem detection and self-tuning. MMON writes out the required statistics for AWR on a scheduled basis.
M000 These are MMON background slave (m000) processes.
NSVn[:] Data Guard Broker NetSlave Process[:] Performs broker network communications between databases in a Data Guard environment
Pnnn: Parallel Query Execution Servers [...] Oracle 7.1.6 introduced the parallel query capability into the database. [...] When using parallel query, you see processes named Pnnn. These are the parallel query execution servers themselves.
Process Spawner Process [...] Spawns Oracle background processes after initial instance startup
In Oracle 10.1, a queue monitor coordinator (QMNC) process [...] dynamically spawns queue monitor slaves (q000 to q009).
Redo data transmitted from the primary database is received by the remote file server (RFS) process on the standby system, where the RFS process writes the redo data to archived log files or standby redo log files.
Performs monitoring management tasks related to Data Guard on behalf of DMON
New Oracle Background Processes [...] SMCO: the space management coordinator process is in charge of coordinating the work of space management-related tasks such as space reclamation, for example.
When a user runs an application program (such as a Pro*C program) or an Oracle tool (such as Enterprise Manager or SQL*Plus), Oracle creates a user process to run the user's application.
A connection is a communication pathway between a user process and an Oracle instance.
A session is a specific connection of a user to an Oracle instance through a user process
V$SESSION displays session information for each current session. [...] SID [...] Session identifier
[...] Oracle assigns a unique session ID into the v$session table for each individual user logged on to Oracle.
SPID VARCHAR2(12) Operating system process identifier
enqueue[:] This is another term for a lock.
latch[:] A simple, low-level serialization mechanism to protect shared data structures in the System Global Area.
Parameter files contain a list of configuration parameters for that instance and database.
V$PARAMETER displays information about the initialization parameters that are currently in effect for the session.
V$SPPARAMETER displays information about the contents of the server parameter file.
At least a significant part, if not all of the code for the ORACLE DBMS kernel, is written in the C programming language. [...] The basic idea behind V$ views is to expose information in C data structures to database administrators. This is done by mapping V$ views to C data structures through some intermediate layers. X$ tables are one of the intermediate layers. They are the layer closest to C [...] Of course the word table in X$ table has a meaning that is almost entirely different from the meaning in a SQL context.
Many X$ table names follow a strict naming convention, where the first few letters represent a layer or module in the ORACLE kernel. [...] Abbreviations used in X$ Fixed Table Names [:]
Oracle Kernel Database Layers
Updated to Oracle 22.214.171.124
Oracle 10g includes a [...] scheduling mechanism to automate routine tasks. [...] It is a collection of procedures and functions in the DBMS_SCHEDULER package. The earlier versions of Oracle included the DBMS_JOB program to schedule jobs; this utility is still available in Oracle 10g.
Oracle Resource Manager is [...] designed to ensure that CPU resources can be allocated fairly between groups of users on a single instance [...]
[...] we performed a basic and common DBA tasks on the two products and measured the time taken and the steps required to complete each task, to assess their relative manageability.
Background dump (bdump) files are generated when an Oracle process experiences unexpected problems.
Every Oracle database has an alert log named alertdb_name.log (where db_name is the name of the database). The alert log captures major changes and events that occur during the running of the Oracle instance, including log switches, any Oracle-related errors, warnings, and other messages. [...] Oracle puts the alert log in the location specified for the BACKGROUND_DUMP_DEST initialization parameter. [...] Commonly, it is located in a directory called bdump, which stands for background dump directory.
In the past, Oracle referred to globalization support capabilities as National Language Support (NLS) features. NLS is actually a subset of globalization support. NLS is the ability to choose a national language and store data in a specific character set. Globalization support enables you to develop multilingual applications and software products that can be accessed and run from anywhere in the world simultaneously.
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