The document provides an overview of the Oracle database including its architecture, components, and features. It discusses Oracle's memory structure consisting of the shared pool, database buffer cache, and redo log buffer. It describes Oracle's process structure including background processes like DBWR, LGWR, PMON and SMON. It also covers Oracle's storage structure such as datafiles, redo logs, control files and the physical and logical storage architectures including tablespaces, segments, extents and blocks.

1. Overview of Oracle Database

2. Part 1. Introduction to Database System
 Introduction to Database
 History of RDBMS
 Entity-Relationship Modeling
 Database Language

3. Introduction to Database

File-Based Approach
 Each program defines and manages its own data
 Limitation


Duplication of data

Data dependence

Incompatibility of files


Separation and isolation of data
Fixed queries/proliferation of application program
Database Approach
 A shared collection of logically related data, designed
to meet the information needs of an organization

4. 
Database Management System(DBMS)
 A software system that enables users to define, create and
maintain the database and provides controlled access to
database
 DDL
 DML : procedural, non-procedural
 Control : security, integrity, concurrency control,
recovery control, user-accessible catalog

Components of the DBMS Environment
 Hardware - Software - Data - Procedures - People

5. 
Advantages of DBMS
- Control of data redundancy - Economy of scale
- Data consistency
- Balance of conflicting requirements
- More information from the same amount of data
- Sharing of data
- Improved data accessibility and responsiveness
- Improved data integrity
- Increased productivity
- Improved security
- Improved maintenance through data
independence
- Enforcement of standards
- Increased concurrency
- Improved backup and recovery services

Disadvantages of DBMS
- Complexity, Size, Cost of DBMSs, Additional H/W costs
- Cost of conversion, Performance, Higher impact of a failure

6. 
Three-Level Database Architecture
 External Level
The users’ view of the database
 Conceptual Level
The community view of the database
 Internal Level
The physical representation of the database on the computer

7. 
Functions of a DBMS
1. Data storage, retrieval, and update
2. A user-accessible catalog
3. Transaction support
4. Concurrency control services
5. Recovery services
6. Authorization services
7. Support for data communication
8. Integrity services
9. Services to promote data independence
10. Utility services

8. 
Components of a DBMS
Programmers
Users
DBA
Application
Programs
Queries
Database
Schema
DML
preprocessor
Query
processor
DDL
compiler
Program
object code
Database
manager
Dictionary
manager
Access
methods
File
manager
System
buffers
Database and
system catalog
DBMS

9. 
Components of Database Manager
Authorization
control
Integrity
checker
Command
processor
Query
optimizer
Transaction
manager
Scheduler
Buffer
manager
Recovery
manager
Data
Manager

10. History of RDBMS

History of DBMS
 1960s - Apollo moon-landing project, GUAM
 mid 1960s - IMS by IBM (hierarchical DBMS)
 mid 1960s - IDS by GE (network DBMS)
 1965 - CODASYL(Conference on Data SYStems
Language)
 1967 -DBTG(Data Base Task Group)
 1970 - E.F.Codd of the IBM Research Lab.
 Late 1970s - System R project at IBM
 1980s - commercial relational DBMS(DB2, Oracle,
Informix..)
 Now - OODBMS, ORDBMS

11. 
Terminology
 Relation : a relation is a table with columns and rows
 Attribute : an attribute is a named column of a relation
 Domain : a domain is the set of allowable values for
one or more attributes
 Tuple : a tuple is a row of a relation
 Degree : the degree of a relation is the number of
attributes it contrains
 Cardinality : the cardinality of a relation is the number
of tuples it contains
 Relational database : a collection of normalized
relation

12. 
Properties of Relations
 The relation has a name that is distinct from all other
relation names
 Each cell of the relation contains exactly on atomic
value
 Each attribute has a distinct name
 The values of an attribute are all from the same domain
 The order of attributes has no significance
 Each tuple is distinct; there are no duplicate tuples
 The order of tuples has no significance, theoretically

13. 
When is a DBMS Relational?
 Foundational rules
Rule 0 : Foundational rule Rule 12 : Nonsubversion rule
 Structural rules
Rule 1 : Information representation
Rule 6 : View updateing
 Integrity rules
Rule 3 : Systematic treatment of null values
Rule 10 : Integrity independance
 Data manipulation rules
Rule2 : Guaranteed access
Rule 4 : Dynamic online catalog based on the
relational model
Rule5 : Comprehensive data sublanguage
Rule7 : High-level insert, update, delete
 Data independence rules
Rule8 : Physical data independence
Rule11 : Distribution independence
Rule 9 : Logical data independence

14. Entity-Relationship Modeling

Concepts of the E-R Modeling
 Entity Types
An object or concept that is identified by the enterprise as having an
independent existence
 Attributes
A property of an entity or a relationship type
 Relationship Types
A meaningful association among entity types

15. 
Conceptual Database Design
 The process of constructing a model of the
information used in an enterprise, independent of all
physical considerations
 Logical Database Design
 The process of constructing a model of the
information used in an enterprise based on a specific
data model, but independent of a particular DBMS and
other physical considerations.

Physical Database Design
 The process of producing a description of the
implementation of the database on secondary storage;
it describes the storage structures and access
methods used to archieve efficient access to the data

16. Database Language

SQL
 1974 - SEQUEL by D.Chamberlin (IBM)
 1975 - SQUARE by Boyce (System R project)
 1976 - SEQUEL/2 (SQL) by Chamberlin and Boyce)
 late 1970 - SQL(Oracle), QUEL(Ingres)
 1982 - Relational Database Language(RDL) : ANSI
 1987 - ISO standard
 1989 - Integrity Enhancement Feature (ISO)
 1992 - SQL2(SQL92) : ISO

17. 
DML
 SELECT
 INSERT
 UPDATE
 DELETE

DDL
 CREATE(DROP) SCHEMA
 CREATE(ALTER, DROP) DOMAIN
 CREATE(ALTER, DROP) TABLE
 CREATE(DROP) VIEW
 CREATE(DROP) INDEX

18. 
Advanced SQL
 View
 Integrity Enhancement Feature
 Primary key
 Unique
 Foreign key
 Access Control
 Embedded SQL
 Host Language Variables
 Application Programming Interface
 Dynamic SQL

19. Part 2. Understanding Oracle Database
 Overview of oracle Database Architecture
 Memory Structure
 Process Structure
 Storage Structure
 New Features

20. Overview of Oracle Architecture
PMON
SMON
RECO
D000
S000
Redo Log
Buffer
SGA
Shared SQL Area
P000
Database Buffer Cashe
* Total SGA Size :
1700 Mbyte
* Fixed Size :
70 Kbyte
* Variavle Size :
490 MByte
TL-812
4,000,000 KByte
Server
1,200,000 KByte
DBW0
CKPT
Data File
Raw Device
USER
2,100 KByte
LGWR
ARCH
Archive Log Mode(50M)

21. Memory Structure : Shared Pool
Shared Pool
Library Cache
Dictionary
Cache
Shared
SQL Area
Control Structures
for example:
PL/SQL Procedures
and Package
Control Structures
for examples;
Locks
Library
Cache handles
and so on ...
Character Set
Conversion
Memory
Network Security
Attributes
and so on ..
Reusable
Runtime
Memory
 Shared Pool Contents
- Text of the SQL or PL/SQL statement
- Parsed form of the SQL or PL/SQL statement
- Execution plan for the SQL or PL/SQL
statements
- Data dictionary cache containing rows of data
dictionary information

Library Cache
- shared SQL area
- private SQL area
- PL/SQL procedures and package
- control structures : lock and library cache handles

Dictionary Cache
- names of all tables and views in the database
- names and datatypes of columns in database tables
- privileges of all Oracle users

SHARED_POOL_SIZE

22. Memory Structure :Database Buffer
Cache
 Database Buffer Cache holds copies of data blocks read from disk
 All users concurrently connected to the system share access to the buffer cache
 Dirty List
 LRU List
 Size = DB_BLOCK_SIZE * DB_BLOCK_BUFFERS
SGA
Shared Pool
Shared SQL
Area
Database Buffer Cache

23. Memory Structure :Redo Log Buffer

Circular buffer containing information about changes made to the database

save it redo entry

Redo Entries is used when Database Recovery

DBWR write contents of Redo Log Buffer to Online Redo Log

LOG_BUFFER
change vector #1
redo record
change vector #1
change vector #1

24. Oracle Processes
SNPn
SMON
PMON
Pnnn
RECO
SGA
Database Buffer Cache
Snnn
Redo Log
Buffer
Offline
Storage
Device
Dedicated
Server
Process
DBWR
Dnnn
LCK0
User
Process
LGWR
ARCH
CKPT
Control
Files
Users
Data
Files
Redo Log
Files

25. Background Process
 DBWR
(Database Writer)
- write all dirty buffers to datafiles
- Use a LRU algorithm to keep most recently used blocks in memory
- Defers write for I/O optimization
 dirty list reaches a threshold length
 A process SCNAS a specifed number of buffer in the LRU without finding free buffer
 A time-out occurs
 DBWR checkpoint occurs
 LGWR
(Log Writer)
- writes redo log entries to disk
 Commit occurs
 The redo log buffers pool becomes one-third full
 DBWR completes cleaning the buffer blocks at a checkpoint
 LGWR time-out
- A commit confirmation is not issued until the tx has been recorded in the redo
log file

26. Cont’d
 PMON
(Process Monitor)
- Cleans up abnormally terminated connection
- Rolls back uncommited transactions
- Releases locks held by a terminated process
- Frees SGA resources allocated to the failed processes
- Database maintenance
 SMON
(System Monitor)
- Performs automatic instance recovery
- Reclaims space used by temporary segments no longer in use
- Merges contiguous area of free space in the datafile

27. Cont’d
 CKPT
(Check Point)
- is enabled by setting the parameter CHECKPOINT_PROCESS=TRUE
- If enabled, take over LGWR’s task of updating files at a checkpoint
- Updates header of datafiles and control files at the end of checkpoint
- More frequent checkpoint reduce recovery time from instance failure
- CKPT improve the performance of database with many database files
 ARCH
(Archiver)
- Copies redo log files to tape or disk for media failure
- Operates only when a log switch occurs
- Is optional and is only needed when in ARCHIVELOG mode
- May write to a tape drive or to a disk
 LCKn
(Lock), Dnnn (Dispatcher), Snnn (Server),
RECO (Recover), Pnnn(Parallel), SNPn(Snapshot process)(Job
Queue),
QMNn(Queue Monitor),

28. Server/User Process
 User
Processes
- A user process is used when a user runs an application program
- Runs the tool/application and is considered the client
- Passes SQL to the server process and receives the results
 Server
Processes
- A server process must place the data in the database buffer cache
- Parce and execute SQL statements
- Read data blocks from disk into the shred database buffers of the SGA
- Return the results of SQL statements to the user process
 Parse : check syntax, security access, object resolution, optimization
 Execute : applies the parse tree to the data, perform a physical read and
change
 Fetch : Passes data to the user (only SELECT)

29. Oracle Files

Datafile

Redo Log Files

Control Files

Parameter File

Archive File

Log File (alert*.log, sqlnet.log, listener.log...)

Trace File

30. Storage Architecture

Physical storage structures
 Data files
 Segments
 Extents
 Blocks

Logical storage structures
 Tablespaces
 Tables / Clusters / Indexes
 Rows
 Columns

31. Physical Storage Architecture

Relationship among Segments, Extents, and Blocks
Segment
96K
Extent
Extent
24K
72K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
Database Blocks
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K

32. Logical Storage Architecture

Relationship between tablespaces and datafiles
Database
System Tablespace
DATA1.ORA
DATA2.ORA
USER Tablespace
DATA3.ORA

33. Cont’d

Objects stored in tablespaces
Tablespace (one or more datafiles)
Table
Table
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
Table
Database Files
Objects
(Physical structures associated
with only one tablespace)
(stored in tablespace may
span serveral datafiles)

34. Block
Header
Table Dictionary
Row Dictionary
Free Space
General Block Information
(Block add, Segment type)
85 ~ 100 bytes
Table info in Cluster
Row info in Block
(2 byte per row)
Row Data
using when New Row
Insert or Update
(pctfree, pctused)
Table or Index Data

35. PCTFREE / PCTUSED
PCTFREE
PCTFREE
PCTUSED
PCTUSED
20% Free space
61% Free space
PCTUSED = 40
PCTFREE = 20


Insert new row until 80%
20% use when Update


Can insert new row when below 60%
When Usage is below 40% (61% Free
space), block is listed in FREELIST

36. Extent
A
set of contiguous database blocks within a datafile.
Extent
are allocated when.
- The segment is created (INITIAL EXTENT)
- The segments grows (NEXT EXTENT)
- The table is altered to allocate extents.
Extent
are de-allocated when the
- The segment is dropped and truncated.
- The segment is larger than optimal and contains free extents
(for rollback segments only)
Each
segment is created with at least on extend( initial extent )
( Rollback segment : 2)
ALTER
TABLE table_name DEALLOCATE UNUSED

37. Segment
a set of one or more extents that contains all the data for a specific type of logical storage
structure within a tablespace
 Data Segment
- A collection of extents that holds all of the data for a table or a cluster
 Index Segment
- A collection of extents that holds all of the index data for search optimization on large tables
and clusters
 Rollback Segment
- A collection of extents that holds rollback data for rollback, read-consistency, or recovery
 Temporary segment
- A collection of extents that holds data belonging to temporary tables created during a sort
operation
 Bootstrap segment
- An extent that contains dictionary definitions for dictionary tables to be loaded when the
database is opened.


38. Oracle Client/Server Architecture
NETWORK
Server b
Client
Application
Server/Server
Client/Server
Server A

Benefit of Client/Server Component
- Database S/W work on Server
- Minimize network resource
- concurrency, consistency, transparency
- Only Server upgrade to increase size
- Minimize Client H/W spec
- concurrency, consistency, transparency