WELCOME TO DBA TECHNOLOGIES
ORACLE DATABASE ARCHITECTURE – 1
By
Mr. PRASAD MYNUMPATI
18 Years Real Time in
INDIA-USA
http://www.dbatechnologies.net/
www.dbatechnologies.net
Building Career With Passion
Architecture
Main components of Architecture
1. ORACLE INSTANCE
SGA (Memory) &
Background Process
2. ORACLE DATABASE
Storage Level
ORACLE Instance Architecture – SGA
What is ORACLE INSTANCE?
Physical Memory (SGA) & Processes
SGA should be able to open in physical memory
What is SWAP?
Swap also a type of file system on HDD, it is used by OS when Real memory usage is at high
Swap must be available before installing Oracle Software
Oracle Instance Architecture – PROCESSES
Each connection to UNIX operating system is processWhile starting up instance – SGA (Memory Structures) – Background Process ($ps)Background process are required to manage memory structures and database files.Some of the important background process are: DBWn, LGWR, SMON, PMON, ARCH,RECO
Instance Architecture
SGA - Mandate and Optional memory structures and background processes
Streams PoolLarge
DBWn LGWR SMON PMON CKPT RECO
What is ORACLE DATABASE?
ORACLE DATABASE is a combination of 3 different types of files
Different types of files (C,R,D)
-Control Files
-Redo log files
-Data files
DB Architecture - Control Files
Control Files – Holds data about database structure (physical database
structural information)
Importance of control file
– Database can not be started with out control file
– Multiplexing to support from failures
– Supports up to 8 file copies
DB Architecture – Control Files
Contents of Control file
• Database Name and database id
• Database creation date and time
• All database file names (data files)
• Location of each data file• Age of each file (Checkpoint Information)
• Current online log sequence number
• Checkpoint number
• Backup information
DB Architecture - Data File
Data FilesStores actual data permanently in ORACLE proprietary files called data files.Data files are going to be on file system like -UNIX
-EXT2
-EXT3
-NTFS (in case of windows)
Minimum 3 data base files are required from 10g -System
-Undo
-Sysaux
DB Architecture - Redo log files
Stores all changes in the form of change vectors for recovery
Changes are saved to Data Files and Redo Log Files – what is the
difference?
Changes to REDO LOG FILES are in the form of change vectors
– Block id
– File id
– Change details
Changes to Data files are in the form of rows and blocks
DB Architecture
Control files : minimum 1. Stores Database structural information. Recommended 3 files.
Disk1Control
Disk2Control
Disk3Control
Data files : Minimum 3 from 10g. Stores data permanently for retrieval purpose.
System Undo Sysaux
Redo log files: Minimum -2
holds all changes in the formof changes vectors for recovery Rego1a
.logRedo2a
.log
Oracle Server
Oracle Server is the combination of Oracle Instance & Oracle database.
Database access is only via Instance
SGA Database
> SelectDBBC SPFrom
Emp;User Process
ControlRedoDataFiles
LC DDC
REDO LOG
BUFFERSBack ground Processes
Logical and Physical aspect of Oracle database
DATABASE
PHYSICAL LOGICAL
ControlFiles
Tables
ViewsData Files
ProceduresRedo LogFiles
Triggers
IS INSTANCE PHYSICAL OR LOGICAL ?
PHYSICAL
LOGICAL
INSTANCE
?NEITHER
IT IS VOLATILE
ORACLE Database TS Architecture
SYSTEM TABLE SPACE
INDEX TABLESPACE
DATA TABLESPACE
TEMPORARY TABLESAPCE
UNDO TABLESPACE
SYSAUX TABLESPACE
Database Architecture – SYSTEM TS
Users should not keep application data on SYSTEM tablespace.It is only to support base tables like.
TAB$COL$IND$
Base Tables are created during the creation of data base to support metadata.
Database Architecture – SYSAUX TS
SYSAUX tablespace introduced in version 10gSupports work load repository Reports such as AWR and ADDM willmake use of SYSAUX to generate reportsHelps in understanding the performance at SERVER level
Database Architecture – UNDO TS
UNDO tablespace is to support image during DML operationsSupports Read consistencyFlashback operationsRollback transactionsContents of UNDO TS type is UNDO it is not permanent
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