Oracle - OS (LC) Oracle Architecture Oracle Day 1 3 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Objectives To Recall RDBMS concepts To introduce ORACLE and its products To introduce Oracle Client/Server Architecture To explain Oracle Physical structure-Data Files, Control Files, Redo Files To explain Oracle Logical Structure- Tablespaces, Segments, Extents, Blocks To introduce Schema objects-Tables, Sequences, Synonyms, Views, Indexes and Clusters To explain Oracle Memory Structures and Background Processes, Data Dictionary 4 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 RDBMS - Overview • Why RDBMS? • Keys • SQL • Embedded SQL • Transaction processing 5 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 What is Oracle? Oracle is a Relational Database Management System. • It is a management system which uses the Relational Data Model. • In the Relational Data Model, data is seen by the users in form of tables. 6 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Oracle Products Oracle broadly sells products in two categories • Database Servers • Application Development Tools 7 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Database Servers • Oracle 10g Database • Oracle 9i Database • Oracle 8i Database 8 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Application Development Tools • Oracle Developer (Includes Forms, Reports, Graphics etc.) • Oracle Designer • Oracle Discoverer • PL/SQL (Technology) 9 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Oracle Database Server Oracle Database server: – Is a database management system that provides an open, comprehensive, integrated approach to information management – Consists of • An Oracle Instance and • An Oracle Database Oracle Server 10 Copyright © 2005, Infosys Technologies Ltd ER/CORP/CRS/DB25/003 Version No.2.0 Oracle Database Server Architecture Control files Datafiles Database Redo Log files Instance SGA Redo Log Buffer Shared Pool Data Dictionary Cache Library Cache DBWRSMONPMON CKPTLGWR Others User process Server process PGA Database Buffer Cache Large Pool Password file Parameter file Archived Log files [...]... ER/CORP/CRS/DB25/003 Version No.2.0 User Process – A program that requests interaction with the Oracle server – Must first establish a connection – Does not interact directly with the Oracle server Server process User process Connection established Database user Copyright © 2005, Infosys Technologies Ltd 25 ER/CORP/CRS/DB25/003 Version No.2.0 Server Process – A program that directly interacts with the Oracle server... Technologies Ltd 23 ER/CORP/CRS/DB25/003 Version No.2.0 Process Structure Oracle takes advantage of various types of processes: – User process: Started at the time a database user requests connection to the Oracle server – Server process: Connects to the Oracle Instance and is started when a user establishes a session – Background processes: Started when an Oracle Instance is started Copyright © 2005,.. .Oracle Database Oracle Database: – Is a collection of data that is treated as a unit – Consists of three file types Oracle Database Datafiles Control files Copyright © 2005, Infosys Technologies Ltd Redo Log files 11 ER/CORP/CRS/DB25/003 Version No.2.0 Oracle Instance Oracle Instance: • Is a means to access an Oracle database • Always open one and only one... 12 Background Processes ER/CORP/CRS/DB25/003 Version No.2.0 Establishing a Connection and Creating a Session Connecting to an Oracle Instance: – Establishing a user connection – Creating a session Connection established Server process Session created Oracle Server User process Database user Copyright © 2005, Infosys Technologies Ltd 13 ER/CORP/CRS/DB25/003 Version No.2.0 Physical Structure The physical... directly interacts with the Oracle server – Fulfills calls generated and returns results – Can be Dedicated or Shared Server Connection established User process Server process Session created Oracle server Database user Copyright © 2005, Infosys Technologies Ltd 26 ER/CORP/CRS/DB25/003 Version No.2.0 Background Processes • Maintains and enforces relationships between physical and memory structures – Mandatory... server processes • Backup and restore operations or RMAN – Does not use an LRU list – Sized by LARGE_POOL_SIZE Copyright © 2005, Infosys Technologies Ltd 22 ER/CORP/CRS/DB25/003 Version No.2.0 Program Global Area – Memory reserved for each user process connecting to an Oracle database – Allocated when a process is created – Deallocated when the process is terminated – Used by only one process PGA Server... Archived redo log file Oracle Database Parameter file Datafiles Control files Redo Log files Archived Log files Password file Copyright © 2005, Infosys Technologies Ltd 14 ER/CORP/CRS/DB25/003 Version No.2.0 Memory Structure • Oracle s memory structure consists of two memory areas known as: – System Global Area (SGA): Allocated at instance startup, and is a fundamental component of an Oracle Instance –... Allocated at instance startup, and is a fundamental component of an Oracle Instance – Program Global Area (PGA): Allocated when the server process is started Copyright © 2005, Infosys Technologies Ltd 15 ER/CORP/CRS/DB25/003 Version No.2.0 System Global Area The SGA consists of several memory structures: • • • • Shared Pool Database Buffer Cache Redo Log Buffer Other structures (for example, lock and latch... recovery Changes recorded within are called redo entries Redo entries contain information to reconstruct or redo changes Size defined by LOG_BUFFER Redo Log Buffer Copyright © 2005, Infosys Technologies Ltd 21 ER/CORP/CRS/DB25/003 Version No.2.0 Large Pool – An optional area of memory in the SGA – Relieves the burden placed on the Shared Pool – Used for: • Session memory (UGA) for the Shared Server... writes: – At commit – When one-third full – When there is 1 MB of redo – Every three seconds – Before DBWn writes Redo Log files Database Copyright © 2005, Infosys Technologies Ltd 29 ER/CORP/CRS/DB25/003 Version No.2.0 System Monitor (SMON) Instance SGA • SMON Datafiles Control files Redo Log files Responsibilities: – Instance recovery • Rolls forward changes in redo logs • Opens database for user access . Tools 7 Copyright © 200 5, Infosys Technologies Ltd ER/CORP/CRS/DB25 /00 3 Version No.2 .0 Database Servers • Oracle 10 g Database • Oracle 9i Database • Oracle 8i Database 8 Copyright © 200 5, Infosys Technologies. – Consists of • An Oracle Instance and • An Oracle Database Oracle Server 10 Copyright © 200 5, Infosys Technologies Ltd ER/CORP/CRS/DB25 /00 3 Version No.2 .0 Oracle Database Server Architecture Control. Oracle - OS (LC) Oracle Architecture Oracle Day 1 3 Copyright © 200 5, Infosys Technologies Ltd ER/CORP/CRS/DB25 /00 3 Version No.2 .0 Objectives To Recall RDBMS concepts To introduce ORACLE