The Oracle Database (commonly referred to as Oracle RDBMS or simply Oracle) consists of a relational database management system (RDBMS) produced and marketed by Oracle Corporation. As of 2008, Oracle had become a major presence in database computing.
Larry Ellison and his friends and former co-workers Bob Miner and Ed Oates started the consultancy 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 previously employed by Ampex.
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).
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 (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.
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I am using Oracle database since 2005. Oracle database was not used very often in projects I had been engaged, but it follows concepts most relational databases do. I am competent in:
Database design,
Writing and optimizing of SQL queries.