What is Oracle Database?

Part 1

" Oracle Database (Commonly referred to as Oracle RDBMS or simply as Oracle) is an object relational database management system produces and marketed by Oracle Corporation. 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 " - Wikipedia

There are three major structure in Oracle Database server Architecture :
          
             1. Memory structure
             2. Process Structure
             3.  Storage Structure

A basic Oracle Database system of an Oracle database and a database instance. The instance is consists of :

             1. Memory structure
             2. Background Process

Memory are called System Global Area (SGA) and contains :

            1.Java pool
            2. Buffer cache
            3. Redo buffer
            4. Shared pool
           5. Streams pool
           6.  Large pool

Outside from SGA are Process Global Area (PGA) that connected to System Global Area.

System Global Area

Memory districts that contain information and control data for a server or foundation process. A PGA is non-shared memory made by Oracle Database when a server or foundation procedure is begun. Access to the PGA is selective to the server procedure. Every server procedure and foundation process has its own PGA. When a table is created, a segment is created to hold its data. A tablespace contains a collection of segments. Logically, a table contains rows of column values. A row is ultimately stored in a database block in the form of a row piece. Content of Database block are  Block Header, free spaces (Growth) and Row data.

Instance for database also we learned on classroom training. The database instances and database go through stages as the database is made for access by the user. " Each instance each database". This function for any valid user can connect connect to the database and perform typical data access operations. There also several type we shutdown the instance shutdown abort, immediate, transactional and normal.

Listener? What is listener? listener or Oracle Net Listener is the gateway to the oracle instance for all nonlocal user connections. As for me, listener are interpreter between user to system. " Bridge ! bridge is a thing that connect between town and island, so that's mean if the bridge are destroyed and other car from town cannot go through to the island and its act as listener." Basically one database can have many listener and default port are 1521.

listener

Also security are one of important element  in Oracle Database. To access the database, a user must be specify a valid database user account and successfully authenticate as require by that user account. each user account has unique username, authentication method, default tablespace, temporary tablespace, user profile, initial consumer group and account status. There has several element on this Oracle Database need to stress it.

 With Oracle database, space is automatically managed by the server. In Oracle database, the features include managed files, free-space management with bitmaps, proactive space management, space reclamation and capacity planning. Segment is a set of extents allocated for a certain logical structure and another types of segments table and cluster segments, index segment, undo segment and temporary segment.

Tablespace

That's all for today! Any question?

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