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International Technology University
Lecture 1
Overview of Oracle Database
1
Part 1. Introduction to Database System
 Introduction to Database
 History of RDBMS
 Entity-Relationship Modeling
 Database Language
2
Introduction to Database

File-Based Approach
 Each program defines and manages its own data
 Limitation


Separation and isolation of data

Duplication of data

Data dependence

Incompatibility of files

Fixed queries/proliferation of application program
Database Approach
 A shared collection of logically related data, designed
to meet the information needs of an organization
3
Introduction to Database

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
4
Introduction to Database

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
5
Introduction to Database

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
6
Introduction to Database

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
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Introduction to Database

Components of a DBMS
Programmers
Application
Programs
Users
Queries
DBA
Database
Schema
DML
Query
DDL
preprocessor
processor
compiler
Program
Database
Dictionary
object code
manager
manager
Access
File
methods
manager
System
Database and
buffers
system catalog
DBMS
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Introduction to Database

Components of Database Manager
Authorization
control
Integrity
Command
Query
checker
processor
optimizer
Transaction
manager
Scheduler
Buffer
Recovery
manager
manager
Data
Manager
9
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
10
RDBMS Terminology

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 contains
 Cardinality : the cardinality of a relation is the number
of tuples it contains
 Relational database : a collection of normalized
relation
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Properties of Relations

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
12
Properties of Relations

When is a DBMS Relational?
 Foundational rules
Rule 0 : Foundational rule Rule 12 : Non-subversion rule
 Structural rules
Rule 1 : Information representation
Rule 6 : View updateing
 Integrity rules
Rule 3 : Systematic treatment of null values
Rule 10 : Integrity independence
 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
Rule 9 : Logical data independence
Rule11 : Distribution independence
13
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
14
Normalization

Normalization
 A technique for producing a set of relations with desirable
properties, given the data requirements of an enterprise
 UNF is a table that contains one or more repeating groups
 1NF is a relation in which the intersection of each row and column contains one
and only one value
 2NF is a relation that is in 1NF and every non-primary-key attribute is fully
functionally dependent on the primary key.
 3NF is a relation that is in 1NF, 2NF in which no non-primary-key attribute is
transitively dependent on the primary key
 BCNF is a relation in which every determinant is a candidate key
 4NF is a relation that is in BCNF and contains no trivial multi-valued
dependency
 5NF is a relation that contains no join dependency
15
Database Views

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
Database Language

DML
 SELECT
 INSERT
 UPDATE
 DELETE

DDL
 CREATE(DROP) SCHEMA
 CREATE(ALTER, DROP) DOMAIN
 CREATE(ALTER, DROP) TABLE
 CREATE(DROP) VIEW
 CREATE(DROP) INDEX
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Structured Query Language - SQL

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
D000
RECO
S000
Redo Log
Buffer
SGA
Shared SQL Area
P000
Database Buffer Cache
* 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
2,100 KByte
LGWR
ARCH
USER
Archive Log Mode(50M)
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Memory Structure : Shared Pool
Shared Pool
 Shared Pool Contents
- Text of the SQL or PL/SQL statement
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
- 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
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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
Database Buffer Cache
Shared Pool
Shared SQL Area
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
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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
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Background Process

DBWR (Database Writer)
- write all dirty buffers to data files
- 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 scans a specified 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 text has been recorded in the redo
log file
26
Cont’d

PMON (Process Monitor)
- Cleans up abnormally terminated connection
- Rolls back uncommitted 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 data files 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(Job Queue),
QMNn(Queue Monitor),
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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
- Parse 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

Data file

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
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
2K
Database Blocks
32
Logical Storage Architecture

Relationship between tablespaces and data files
Database
System Tablespace
DATA1.ORA
DATA2.ORA
USER Tablespace
DATA3.ORA
33
Cont’d

Objects stored in tablespaces
Tablespace (one or more data files)
Table
INDEX
INDEX
Table
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
INDEX
Table
Database Files
Objects
(Physical structures associated
with only one tablespace)
(stored in tablespace may
span several data files)
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
PCTUSED
20% Free space
61% Free space
PCTFREE = 20
 Insert new row until 80%
 20% use when Update
PCTUSED = 40
 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 data file.
 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
39
SQL*Net

What is SQL*Net?
- Oracle’s Client/Server middleware product
- transparent connection from client tool to DB ( from on DB to another )
- works across multiple network protocol and operation system

What is TNS?
- Transparent Network Substrate
- Oracle’s Network applications to access the underlying network protocols transparently
- TNS-based application, Oracle Protocol Adapters, Network software like TCP/IP

Configuration File
- TNSNAME.ORA ( Client )
- TNSNAV.ORA ( Client )
- SQLNET.ORA ( Client, Server )
- LISTENER.ORA ( Server )
40
SQL*Net Configuration

TNSNAME.ORA
info =
(DESCRIPTION=
(ADDRESS_LIST=
(ADDRESS=
(PROTOCOL=tcp)
(HOST=brinfoa01)
(PORT=1521)
)
)
(CONNECT_DATA=
(SID=BRBINFO1)
)
)

SQLNET.ORA
# SQLNET.EXPIRE_TIME = 0
SQLNET.AUTHENTICATION_S
ERVICES=(none, beq)

LISTENER.ORA
LISTENER=
(ADDRESS_LIST=
(ADDRESS=
(PROTOCOL=tcp)
(HOST=brinfoa01)
(PORT=1521)
)
)
SID_LIST_LISTENER=
(SID_LIST=
(SID_DESC=
(SID_NAME=BRBINFO1)
(ORACLE_HOME=/oracle7/oracle7)
(ENVS='EPC_DISABLED=TRUE')
)
)
STARTUP_WAIT_TIME_LISTENER=0
CONNECT_TIMEOUT_LISTENER=0
LOG_DIRECTORY_LISTENER=/oracle7/oracle7/network/log
LOG_FILE_LISTENER=listener
TRACE_LEVEL_LISTENER=OFF
41
Networking Challenge
Networking Challenge

Support large mission-critical
client/server, and provide migration
path towards distributed object
architecture

Focus
1. Scalability : Connection Pooling, Multiplexing(Connection Manager)
2. Manageability : Configuration-free installation option,
Centralized client administration, Automated client configuration
3. Security : Oracle Security Server
42
ODBC / oo4o / JDBC
 ODBC (Open Database Connectivity )
- Provide a way for client program (eg VB, Excel, Access) to access database
- is a standardized API, developed according to the specification of the SQL
Access Group, than allows one to connect to SQL database
 oo4o (Oracle Object for OLE)
- a middleware product manufactured by Oracle that allows native access to Oracle7
databases from client applications via the Microsoft OLE standard
- OLE 2.0 Automation Server, Oracle Data Control, Two C++ Class Library
 JDBC (Java Database Connectivity )
- a set of classes and interfaces written in Java to allow other Java programs to send
SQL statements to a relational database management system
- JDBC Thin for Java applets, JDBC OCI for Java application
43