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1. 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

2. Architecture
Main components of Architecture
1. ORACLE
INSTANCE
SGA (Memory) &
Background Process
2.
ORACLE DATABASE
Storage Level

3. 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

4. Oracle Instance Architecture – PROCESSES
Each connection to UNIX operating system is process
While 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

5. Instance Architecture
SGA - Mandate and Optional memory structures and background processes
Streams Pool
Large
DBWn
LGWR
SMON
PMON
CKPT
RECO

6. 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

7. 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

8. 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

9. DB Architecture - Data File
Data Files
Stores 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

10. 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

11. DB Architecture
Control files : minimum 1. Stores Database structural information.
Recommended 3 files.
Disk1
Control
Disk2
Control
Disk3
Control
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 form
of changes vectors for recovery
Rego1a
.log
Redo2a
.log

12. Oracle Server
Oracle Server is the combination of Oracle Instance &
Oracle database.
Database access is only via Instance
SGA
Database
> Select
From
Emp;
User Process
DBBC
SP
LC
DDC
REDO LOG
BUFFERS
Back ground Processes
Control
Redo
Data
Files

13. Logical and Physical aspect of Oracle database
DATABASE
PHYSICAL
LOGICAL
Control
Files
Data Files
Redo Log
Files
Tables
Views
Procedures
Triggers

14. IS INSTANCE PHYSICAL OR LOGICAL ?
LOGICAL
INSTANCE
PHYSICAL
?
NEITHER
IT IS VOLATILE

15. ORACLE Database TS Architecture
SYSTEM TABLE SPACE
SYSAUX TABLESPACE
UNDO TABLESPACE
TEMPORARY TABLESAPCE
DATA TABLESPACE
INDEX TABLESPACE

16. 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.

17. Database Architecture – SYSAUX TS
SYSAUX tablespace introduced in version 10g
Supports work load repository Reports such as AWR
and ADDM willmake use of SYSAUX to generate
reports
Helps in understanding the performance at SERVER
level

18. Database Architecture – UNDO TS
UNDO tablespace is to support image during DML
operations
Supports Read consistency
Flashback operations
Rollback transactions
Contents of UNDO TS type is UNDO it is not
permanent

19. Building career with passion
QUESTION AND ANSWER SESSION
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