Architecture of Oracle Database Management System

Oracle is a Relational Database Management System (RDBMS), which uses Relational Data Model to store its database and SQL (commonly abbreviated as Structured Query Language) to process the stored data.

physical structure:
one or more earful files, Two of fresh log files, One control file.


Logical structure:
Table spaces, Segments, Extents, Knowledge blocks.

The data files contain all user data in terms of tables, index, and views. The log files contain the word to unlatched and be recovered, of Undone after a transaction ( Rollback ). The predomination file physical data, media information to open and manage data files. If the control file is struck the server leave not be able to open are use the database even if the database is undamaged. What are the Back ground processes in Augur and what are they.?

Architecture of Oracle Database Management System


There are basically 9 Processes but in a general system we need to mention the first five background processes. They do the house keeping activities for the Oracle and are common in any system.


1 ) Data Base Writer ( DBWR ):: Data Base Writer Writes Modified blocks fromDatabase buffer cache to Data Files. This is required since the data is not written whenever a transaction is commited.


2 ) LogWriter ( LGWR ):: LogWriter writes the redo log entries to disk. Redo Log data is generated in redo log buffer of SGA. As transaction
commits and log buffer fills, LGWR writes log entries into a online redo log file.


3 ) System Monitor ( SMON ):: The Cast Monitor performs instance recovery at present startup. This is useful for atonement from system failure.


4) Process Monitor ( PMON ):: The Process Monitor peforms process recovery when user Process fails. Pmon Clears and Frees resources that process was using.


5) CheckPoint ( CKPT ):: At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate the most recent checkpoint.


6) Archieves ( ARCH ):: The Archiver copies online redo log files to archival storal when they are busy.


7 ) Recoveror ( RECO ):: The Recoveror is used to resolve the distributed transaction in network


8 ) Dispatcher ( Dnnn ):: The Dispatcher is useful in Multi Threaded Architecture


9 ) Lckn:: We can have upto 10 lock processes for inter instance locking in parallel sql

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