Oracle Database

Releases and versions

Oracle products follow a custom release-numbering and -naming convention. The "c" in the current release, Oracle Database 18c, 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".^[8] Oracle's RDBMS release numbering has used the following codes:

The Oracle Database Administrators Guide includes a brief history on some of the key innovations introduced with each major release of Oracle Database.

Patch updates and security alerts

Oracle Corporation releases Critical Patch Updates (CPUs) or Security Patch Updates (SPUs)^[12] 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.

• Customers may receive release notification by email.
• White Paper: Critical Patch Update Implementation Best Practices

Database Cloud Services

Oracle Corporation provides a 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).^[13]

Database editions

As of 2017, the latest Oracle Database version (12.2.0.1) comes in three editions for on-premises deployments^[14]:

• Oracle Database Enterprise Edition (EE): offers industry-leading scalability and reliability in both clustered and single system configurations and imposes no limitation on server resources available to the database.
• Oracle Database Standard Edition 2 (SE2): intended for small- to medium-sized implementations, SE2 includes Real Application Clusters and may be deployed on servers or clusters with a maximum of 2 sockets total and capped to use a maximum of 16 concurrent user threads. SE2 uses the same code base as EE, and therefore upwardly compatible and simple to upgrade to EE.
• Oracle Database Personal Edition (PE): A single-user, single-machine development and deployment license that allows use of all database features. PE is upwardly compatible to SE2 and EE.

Oracle Corporation also makes the following edition available:

• Oracle Database Express Edition (XE), a free-to-use entry-level version of Oracle Database available for Windows and Linux platforms limited to using only one CPU, up to 1 GB of RAM and storing up to 11 GB of user data. It provides a subset of SE2 functionality (lacking features such as Java Virtual Machine, managed backup and recovery, high availability and compression), is community-supported and comes with its own license terms. XE was first introduced in 2005 with Oracle Database 10g Release 2 with a limitation to a maximum of 4 GB of user data. XE for Oracle Database 11g was released on 24 September 2011, and increased user data capacity to 11 GB.

Up to (and including) Oracle Database 12c release 12.1.0.1, Oracle also offered the following:

• Oracle Database Standard Edition (SE) for single or clustered servers with a maximum capacity of 4 CPU sockets. It was largely the same as the current SE2 edition and included Real Application Clusters for use on server clusters with a maximum of 4 CPU sockets.
• Oracle Standard Edition One (SE1), was first introduced with Oracle Database 10g. It offered the same features as SE and was licensed to run on single servers with a maximum of 2 CPU sockets.

Oracle Corporation discontinued SE and SE1 with the 12.1.0.2 release, and stopped offering new licenses for these editions on December 1, 2015.

Supported platforms

Oracle Database 12c is supported on the following OS and architecture combinations:

• Linux on x86-64 (only Red Hat Enterprise Linux, Oracle Linux and SUSE distributions are supported^[15])
• Microsoft Windows on x86-64
• Oracle Solaris on SPARC and x86-64
• IBM AIX on POWER Systems
• IBM Linux on z Systems
• HP-UX on Itanium

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.^[16]

Database options

The Oracle Database offers a wide range of options^[17] 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.^[18] All Database Options are only available for Enterprise Edition and offered for an extra cost.^[17][19] 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.^[20]

Availability

• Oracle Active Data Guard extends Oracle Data Guard functionality with advanced features, allowing read-only access to data in a physical standby database to offload primary of such tasks as reporting, ad-hoc queries, data extraction and backup, offloading redo transport and minimizing standby impact on commit response times (using Far Sync feature), providing option for rolling upgrades for non-RAC customers, managing clients workload across replicated database and improving automated service failover (using Global Data Services), etc.

Scalability

• Oracle Real Application Clusters (RAC) is the computer cluster version of Oracle Database.
• Oracle RAC One Node is a one-node version of Oracle Real Application Clusters, providing capabilities for database failover and high availability in the form of rolling upgrades, online instance migration, application continuity and automated quality of service management.

Analytics

• Oracle Advanced Analytics allows access to in-database data mining algorithms and use of Oracle R Enterprise functionality, an integration with open-source R statistical programming language and environment.
• Oracle Partitioning allows partitioning of tables and indices, where large objects are stored in database as a collection of individual smaller pieces at the same time appearing on application level as a uniform data object.
• Oracle On-Line Analytical Processing (OLAP) is Oracle implementation of online analytical processing.
• Oracle data models: pre-built data models with database analytics and business intelligence capabilities for specific industries including
  • Retail Data Model
  • Communications Data Model
  • Airlines Data Model
  • Utilities Data Model

Performance

• Oracle Advanced Compression complements Enterprise Edition basic table compression feature with comprehensive data compression and Information Lifecycle Management capabilities, including those specifically tailored to Oracle's engineered systems, like Oracle Exadata.
• Oracle Database In-Memory, an in-memory, column-oriented data store, has been seamlessly integrated^[18] into the Oracle Database. This technology aims to improve the performance of analytic workloads without impacting the performance of transactions that continue to use Oracle's traditional row format in memory. The product's performance comes through the in-memory, columnar compressed format and through the use of SIMD vector processing (Single Instruction processing Multiple Data values).
  • In-Memory Aggregation improves performance of typical analytic queries using efficient in-memory arrays for joins and aggregation.^[21]
• Oracle Real Application Testing enable testing of system changes in a simulation of production-level workload and use.
• Oracle TimesTen Application-Tier Database Cache allows caching subsets of a database in the application tier for improved response time. It is built using Oracle TimesTen In-Memory Database.

Security

• Oracle Advanced Security provides Transparent Data Encryption and Data Redaction security features, the former allowing encryption of data stored in a database (all or a subset of it), exported using Data Pump, or backed up using Oracle Recovery Manager, and the latter allowing redaction of sensitive database data (e.g., credit card or social security numbers) returned to database applications.
• Oracle Database Vault enforces segregation of duties, principle of least privilege and other data access controls, allowing protection of application data from access by privileged database users.
• Oracle Label Security is a sophisticated and flexible framework for a fine-grained label based access control (LBAC) implementation.

Management

• Oracle Multitenant is the capability that allows database consolidation and provides additional abstraction layer. In a Multitenant configuration, one Oracle database instance known as "container database" (CDB) acts as a federated database system for a collection of up to 252 distinct portable collections of database objects, referred to as "pluggable databases" (PDB), each appearing to an outside client as a regular non-CDB Oracle database.
• Management Packs: integrated set of Oracle Enterprise Manager tools for maintaining various aspects of Oracle Database including:
  • Diagnostics Pack
  • Tuning Pack
  • Database Lifecycle Management Pack
  • Data Masking and Subsetting Pack
  • Cloud Management Pack for Oracle Database

Developers

• Oracle Spatial and Graph^[22] complements the Oracle Locator feature (available in all editions of Oracle Database^[23]) with advanced spatial capabilities enabling the development of complex geographic information systems and includes network data model and RDF/OWL Semantic graphs

Integration

• Oracle GoldenGate 11g (distributed real-time data acquisition)

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. Such "features" may include (for example):

• Automatic Storage Management
• Clusterware
• Data Aggregation and Consolidation
• Data Guard for high availability
• Generic Connectivity for connecting to non-Oracle systems.
• Database Resource Manager (DRM), which controls the use of computing resources.^[24]
• Expression filtering^[25]
• Fast-start parallel rollback^[26]
• Fine-grained auditing (FGA) (in Oracle Enterprise Edition)^[27] supplements standard security-auditing features^[28]
• Flashback for selective data recovery and reconstruction^[29]
• Heterogeneous Services (HS), providing connectivity to non-Oracle systems and code.^[30]
• iSQL*Plus, a web-browser-based graphical user interface (GUI) for manipulating data in an Oracle database (compare SQL*Plus)
• Oracle Data Access Components (ODAC), tools that consist of:^[31]
  • Oracle Data Provider for .NET (ODP.NET)^[32]
  • Oracle Developer Tools (ODT) for Visual Studio
  • Oracle Providers for ASP.NET
  • Oracle Database Extensions for .NET
  • Oracle Provider for OLE DB
  • Oracle Services for Microsoft Transaction Server
• Oracle-managed files (OMF) – a feature allowing automated naming, creation and deletion of datafiles at the operating-system level.
• Recovery Manager (RMAN) for database backup, restoration and recovery
• SQL*Plus, a program that allows users to interact with Oracle database(s) via SQL and PL/SQL commands on a command-line. Compare iSQL*Plus.
• SQLcl, a command-line interface for queries, developed on the basis of Oracle SQL Developer^[33]
• Universal Connection Pool (UCP), a connection pool based on Java and supporting JDBC, LDAP, and JCA^[34]
• Virtual Private Database^[35] (VPD), an implementation of fine-grained access control.^[36]
• Oracle Application Express, a no-cost environment for database-oriented software-development^[37]
• Oracle Text uses standard SQL to index, search, and analyze text and documents stored in the Oracle database.
• Workspace Manager version-enables tables^[38] using the WMSYS schema.^[39]

Multi-model support

Oracle database provides a long list of supported data models that can be used and managed inside Oracle database:

• JSON document support^[40]Oracle Database supports JavaScript Object Notation (JSON) data natively with relational database features, including transactions, indexing, declarative querying, and views.^[41].
• Oracle Spatial and Graph Oracle Database provides native support for managing spatial and location data
  • Oracle Locator – a freely-available subset of Oracle Spatial and Graph
• Oracle XML DB,^[42] or XDB,^[43], a no-cost component in each edition of the database, provides high-performance technology for storing and retrieving native XML.
• Oracle Text^[44], a no-cost component in each edition of the database. It provides native support for managing free text, in multiple languages inside the database.
• Oracle Multimedia (known as "Oracle interMedia" before Oracle 11g) for storing and integrating multimedia data within a database^[45]
• Object-relational database^[46] support, a no-cost component in each edition of the database. It provides native support for objects inside the database.

Utilities

Oracle Corporation classifies as "utilities" bundled software supporting data transfer, data maintenance and database administration.^[47]

Utilities included in Oracle database distributions include:

• Data Pump utilities, which aid in importing and exporting data and metadata between databases^[48]
• SQL*Loader, utility that facilitates high performance data loading.
• oradebug – interfaces with Oracle session tracing^[49]

Tools

As of 2007 Oracle Corporation had started a drive toward "wizard"-driven environments with a view to enabling non-programmers to produce simple data-driven applications.^[50]

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 REST Data Services (ORDS) function as a Java EE-based alternative to Oracle HTTP Server,^[51] providing a REST-based interface to relational data.^[52]

Users can also develop their own applications in Java and in PL/SQL, optionally using tools such as:

• Oracle Forms
• Oracle JDeveloper
• Oracle Reports

The Database Upgrade Assistant (DBUA)^[53] provides a GUI for the upgrading of an Oracle database.^[54]

JAccelerator (NCOMP) – a native-compilation Java "accelerator", integrates hardware-optimized Java code into an Oracle 10g database.^[55]

Oracle's OPatch provides patch management for Oracle databases.^[56]

The SQLTXPLAIN tool (or SQLT) offers tuning assistance for Oracle SQL queries.^[57]

External routines

PL/SQL routines within Oracle databases can access external routines registered in operating-system shared libraries.^[59][60] The DBMS_SCHEDULER package can invoke external scripts at the operating-system level from PL/SQL.

Database support options

Users who have Oracle support contracts can use Oracle's "My Oracle Support" or "MOS"^[61] 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^[62] 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)^[63] can verify and isolate host system environmental issues that may affect the performance of Oracle software.

Database-related guidelines

Oracle Corporation also endorses certain practices and conventions as enhancing the use of its database products. These include:

• Oracle Maximum Availability Architecture (MAA)^[64] guidelines on developing high-availability systems
• Optimal Flexible Architecture (OFA), blueprints for mapping Oracle-database objects to file-systems

Oracle Certification Program

The Oracle Certification Program, a professional certification program, includes the administration of Oracle Databases as one of its main certification paths. It contains three levels:

1. Oracle Certified Associate (OCA)
2. Oracle Certified Professional (OCP)
3. Oracle Certified Master (OCM)

User Groups

A large number of User Groups for Oracle Database administrators, developers and users has been established on geographical/region, industry and product basis, including:

• Geographical/regional user groups^[65] (e.g. The Independent Oracle Users Group (IOUG))
• Industry-centric user groups (e.g. Oracle Health Sciences User Group)
• Product-centric user groups (e.g. The OakTable Network)

The Oracle User Group communities also host regular events for customers/users to share their experiences and knowledge.

Competition

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.

Pricing

Storage

The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files ("datafiles").^[75] 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.^[76]

Database schema

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.^[81]

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.

Other default schemas^[82][83] include:

• 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.^[84])
• BI, IX, HR, OE, PM, and SH (expanded sample schemas^[85] containing more data and structures than the older SCOTT schema).

Process architectures

Concurrency and locking

Oracle databases control simultaneous access to data resources with locks (alternatively documented as "enqueues").^[115] The databases also use "latches" – low-level serialization mechanisms to protect shared data structures in the System Global Area.^[116]

Oracle locks fall into three categories:^[117]

• DML locks (or data locks) protect data
• System locks (including latches, mutexes and internal locks) protect internal database structures like data files.
• DDL locks (or data dictionary locks) protect the structure of schema objects.

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

• CREATE INDEX online
• ALTER INDEX rebuild online
• ALTER TABLE add column not null with default value
• ALTER TABLE add constraint enable no validate
• ALTER TABLE modify constraint validate
• ALTER TABLE add column (without any default)
• ALTER INDEX visible / invisible
• ALTER INDEX parallel / no parallel

Non-blocking ddl's added to the list in 12.1

• DROP INDEX online (backported to 11.2)
• ALTER TABLE set unused column online
• ALTER TABLE drop constraint online
• ALTER INDEX unusable online
• ALTER TABLE modify column visible / invisible
• ALTER TABLE move partition / sub-partition online
• ALTER TABLE add nullable column with default value

Non-blocking ddl's added to the list in 12.2

• ALTER TABLE split partition [sub-partition] online
• ALTER TABLE move online (move of a non-partitioned table)
• ALTER TABLEe modify partition by .. online (to convert a non-partitioned table to partitioned state)

Non-blocking ddl's added to the list in 18.1

• ALTER TABLE merge partition online
• ALTER TABLE modify partition by .. online (to change the partitioning schema of a table)

Configuration

Database administrators control many of the tunable variations in an Oracle instance by means of values in a parameter file.^[118] 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)^[119] defaults to the format spfile<SID-name>.ora. Within an SQL-based environment, the views V$PARAMETER^[120] and V$SPPARAMETER^[121] give access to reading parameter values.

Implementation

The Oracle DBMS kernel code depends on C programming. Database administrators have limited access to Oracle-internal C structures via V$ views and their underlying X$ "tables".^[122]

Layers or modules in the kernel (depending on different releases) may include the following (given with their inferred meaning):^{[123][124][125]}

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

Logging and tracing

Various file-system structures hold logs and trace files, which record different aspects of database activity. Configurable destinations for such records can include:

• background dump (bdump) destination: contains files generated when an Oracle process experiences unexpected problems.^[130] Also holds the "alert log".^[131]
• core dump (cdump) destination
• user dump (udump) destination