Oracle
An Oracle database consists of a collection of data managed by an Oracle database management system. Popular generic usage also uses the term to refer to the Oracle DBMS management software, but not necessarily to a specific database under its control.
One can refer to the Oracle database management system unambiguously as Oracle DBMS or (since it manages databases which have relational characteristics) as Oracle RDBMS.
Oracle Corporation itself blurs the very useful distinction between:
- data managed by an Oracle RDBMS
- an Oracle database, and
- the Oracle RDBMS software itself
when it refers nowadays to the Oracle RDBMS (the software it sells for the purpose of managing databases) as the Oracle Database. The distinction between the managed data (the database) and the software which manages the data (the DBMS / RDBMS) relies, in Oracle's marketing literature, on the capitalisation of the word database.
Oracle Corporation produces and markets the Oracle DBMS, which many database applications use extensively on many popular computing platforms.
Larry Ellison and his friends and former co-workers Bob Miner and Ed Oates - who had started a consultancy called Software Development Laboratories (SDL) - developed the original Oracle DBMS software. They called their finished product Oracle after the code name of a CIA-funded project they had worked on while previously employed by Ampex.
Database structure
An Oracle database comprises an instance and data storage. The instance 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 users refer to the server-side memory-structure as the SGA (System Global Area). The SGA typically holds cache information like data-buffers, SQL commands and user information. In addition to storage, the database consists of online redo logs (which hold transactional history). Processes can in turn archive the online redo logs into archive logs (offline redo logs), which provide the basis (if necessary) for data recovery and for some forms of data replication.
The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files. Tablespaces can contain various types of segments, for example, 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. At the physical level, data files comprise one or more data blocks, where the blocksize can vary.
Oracle keeps track of its data storage with the help of information stored in the SYSTEM tablespace. The SYSTEM tablespace contains the data dictionary - and often (by default) 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 which can store space management information in bitmaps in their own headers rather than in the SYSTEM tablespace (as happens with the default "dictionary-managed" tablespaces).
If the Oracle database administrator has instituted Oracle RAC (Real Application Clusters), then multiple instances, usually on different servers, attach to a central storage array. This scenario offers numerous advantages, most importantly performance, scalability and redundancy. However, support becomes more complex, and many sites do not use RAC. In version 10g, grid computing has introduced shared resources where an instance can use (for example) CPU resources from another node (computer) in the grid.
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.
Older Oracle database installations (pre-10g) traditionally came with a default schema called scott. After the installation process has set up the sample tables, the user can log 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.)
Version numbering conventions
Other Oracle products may become confused with the Oracle RDBMS — these have historically followed their own release-numbering and naming conventions. As of the RDBMS 10g release, Oracle Corporation seems to have started to make an effort to standardize all current versions of its major products using the "10g" label, although some sources often refer to Oracle Applications Release 11i as Oracle 11i. Major database-related products and some of their versions include:- Oracle Application Server 10g (aka Oracle AS 10g) — a middleware product;
- Oracle Applications Release 11i (aka Oracle e-Business Suite, Oracle Financials or Oracle 11i) — a suite of business applications;
- Oracle Developer Suite 10g (9.0.4);
- Oracle JDeveloper 10g — a Java integrated development environment;
Oracle's numbering conventions have confused many people; they warrant a brief explanation. Since version 7, Oracle's RDBMS release numbering has used the following codes:
- Oracle7: 7.0.16 — 7.3.4
- Oracle8 Database: 8.0.3 — 8.0.6
- Oracle8i Database Release 1: 8.1.5.0 — 8.1.5.1
- Oracle8i Database Release 2: 8.1.6.0 — 8.1.6.3
- Oracle8i Database Release 3: 8.1.7.0 — 8.1.7.4
- Oracle9i Database Release 1: 9.0.1.0 released May 2002
- Codenamed "the last database"
- 9.0.1.5 (Latest current patchset as of December 2003)
- Oracle9i Database Release 2: 9.2.0.1 — 9.2.0.8 (Latest current patchset as of August 2006)
- Oracle Database 10g Release 1: 10.1.0.2 — 10.1.0.5 (Latest current patchset as of February 2006)
- Oracle Database 10g Release 2: 10.2.0.1 — 10.2.0.2 (Latest current patchset as of March 2006)
The version-numbering syntax within each release follows the pattern: major.maintenance.application-server.component-specific.platform-specific.
For example, "10.2.0.1 for 64-bit Solaris" means: 10th major version of Oracle, maintenance level 2, Oracle Application Server (OracleAS) 0, level 1 for Solaris 64-bit.
The Oracle Administrator's Guide offers further information on Oracle release numbers. Oracle provides a table showing the latest patch set release by major release, operating system and hardware architecture.
Oracle Database 10g Release 1(10.1.0.3)
Oracle Database 10g Release 1 (10.1.0.3)Enterprise/Standard Edition for Linux Itanium
| ||||||||||||||||||||||||||||
 | Linux_IA64_CCD_10_1_0_3_Disk1.cpio.gz (630,810,360 bytes) (cksum - 2185536258)*Includes: Examples, HTML DB, HTTP Server, JPublisher, JavaVM ncomps, Legato Single Server, Text Knowledgebase, InterMedia ncomps | |
| Oracle Application Express (formerly HTML DB) v2.0 (56,104,916 bytes) - released 21-SEP-2005 | |
| Oracle Application Express (formerly HTML DB) v1.6 (55,219,364 bytes) - released 30-DEC-2004 |
Oracle Database 10g Client Release 1 (10.1.0.3) for Linux Itanium
| Linux_IA64_Client_10_1_0_3_Disk1.cpio.gz (452,049,915 bytes) (cksum - 1327104796) | |
| Linux_IA64_CRS_10_1_0_3_Disk1.cpio.gz (189,663,936 bytes) (cksum - 771267648) | |
| gtwy_10103_linux_itanium.cpio.gz (278,361,245 bytes) (cksum - 990276436) | |
| Instant Client allows you to run your applications without installing the standard Oracle client or having an ORACLE_HOME. OCI, OCCI, ODBC, and JDBC applications work without modification, while using significantly less disk space than before. Even SQL*Plus can be used with Instant Client. No recompile, no hassle |
posted by sagar @ 2:20 AM
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