Introduction to the Oracle Server

8/9/2019 Introduction to the Oracle Server

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Introduction to the Oracle

Server

Submitted by:

Harleen kaur7040301091


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Overview of the Oracle server

It provides an overview of the Oracle server. The topics include:

Database Structure and Space Management Overview

Data Access Overview

Memory Structure and Processes Overview

Application Architecture Overview

Distributed Databases Overview

Data Concurrency and Consistency Overview

Database Security Overview

Database Administration Overview Data Warehousing Overview

High Availability Overview

Content Management Overview


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Database Structure and Space Management Overview

An Oracle database is a collection of data treated as aunit

The purpose of a database is to store and retrieve related

information In general, a server reliably manages a large amount of

data in a multiuser environment so that many users canconcurrently access the same data

A database server also prevents unauthorized access andprovides efficient solutions for failure recovery

The database has logical structures and physicalstructures


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Logical Database Structures

The logical structures of an Oracle database include schema

objects, data blocks, extents, segments, and tablespaces A schema is a collection of database objects. A schema is

owned by a database user and has the same name as thatuser

Schema objects are the logical structures that directly refer to

the database's data. Schema objects include structures liketables, views, and indexes.

Oracle database data is stored in data blocks

The next level of logical database space is an extent. Anextent is a specific number of contiguous data blocks,

obtained in a single allocation, used to store a specific type ofinformation.

Above extents, the level of logical database storage is asegment


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Physical Database Structures

physical database structures of an Oracle database, including datafiles,

redo log files, and control files EveryOracle database has one or more physical datafiles. The datafiles

contain all the database data

EveryOracle database has a set of two or more redo log files. The primaryfunction of the redo log is to record all changes made to data. If a failureprevents modified data from being permanently written to the datafiles,

then the changes can be obtained from the redo log, so work is never lost. EveryOracle database has a control file. A control file contains entries that

specify the physical structure of the database. For example, it contains thefollowing information:

Database name

Names and locations of datafiles and redo log files

Time stamp of database creation

Like the redo log, Oracle lets the control file be multiplexed for protectionof the control file


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Data Access Overview

This section explains how Oracle adheres to industryaccepted standards for data access languages, andhow Oracle controls data consistency and dataintegrity. This section includes the following topics:

"SQL Overview"

"Objects Overview"

"PL/SQL Overview"

"Java Overview"

"TransactionsOverview"

"Data Integrity Overview"

"SQL*Plus Overview"


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OVERVIEWS

SQL Overview

SQL (pronounced SEQUEL) is the programming language thatdefines and manipulates the database. SQL databases arerelational databases, which means that data is stored in a setof simple relations.

PL/SQL Overview

PL/SQL is Oracle's procedural language extension to SQL.PL/SQL combines the ease and flexibility of SQL with theprocedural functionality of a structured programminglanguage, such as IF ... THEN, WHILE, and LOOP.

Java Overview

Java is an object-oriented programming efficient forapplication-level programs. Java has key features that make itideal for developing server applications


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Transactions Overview

A transaction is a logical unit of work that comprises one ormore SQL statements run by a single user. According to theANSI/ISO SQL standard, with which Oracle is compatible, atransaction begins with the user's first executable SQLstatement. A transaction ends when it is explicitly committedor rolled back by that user.

Data Integrity OverviewData must adhere to certain business rules, as determined bythe database administrator or application developer. Forexample, assume that a business rule says that no row in theinventory table can contain a numeric value greater than nine

in the sale_discount column. If an INSERT or UPDATEstatement attempts to violate this integrity rule, then Oraclemust roll back the invalid statement and return an error to theapplication. Oracle provides integrity constraints and databasetriggers to manage data integrity rules


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Memory Structure and Processes Overview

An Oracle server uses memory structures and

processes to manage and access the database

The architectural features discussed in this section

enable the Oracle server to support:

Many users concurrently accessing a single database


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Application Architecture Overview

There are two common ways to architect a database: client/server or

multitier Client/Server Architecture

An Oracle database system can easily take advantage of distributedprocessing by using its client/server architecture. In this architecture, thedatabase system is divided into two parts: a front-end or a client and aback-end or a server.

Multitier Architecture: Application ServersA multitier architecture has the following components:

A client or initiator process that starts an operation

One or more application servers that perform parts of the operation. Anapplication server provides access to the data for the client and performssome of the query processing, thus removing some of the load from the

database server. It can serve as an interface between clients and multipledatabase servers, including providing an additional level of security.

An end or database server that stores most of the data used in theoperation


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DistributedDatabases Overview

A distributed database is a network of databases managed by

multiple database servers that are used together They are not usually seen as a single logical database

The data of all databases in the distributed database can besimultaneously accessed and modified.

The primary benefit of a distributed database is that the data

of physically separate databases can be logically combinedand potentially made accessible to all users on a network.

Each computer that manages a database in the distributeddatabase is called a node. The database to which a user isdirectly connected is called the local database. Any additionaldatabases accessed by this user are called remote databases.When a local database accesses a remote database forinformation, the local database is a client of the remoteserver. This is an example of client/server architecture

A database link describes a path from one database to another


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Replication Overview

Replication is the process of copying and maintainingdatabase objects, such as tables, in multiple

databases that make up a distributed databasesystem.

Changes applied at one site are captured and storedlocally before being forwarded and applied at each ofthe remote locations. Oracle replication is a fullyintegrated feature of the Oracle server.

It is not a separate server.

Replication means that the same data is available atmultiple locations. For example, the employees tablecan be available at db1, db2, and db3.


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Data Concurrency and Consistency Overview

ConcurrencyA primary concern of a multiuser databasemanagement system is how to control concurrency,which is the simultaneous access of the same data by

many users. Without adequate concurrency controls,data could be updated or changed improperly,compromising data integrity.

If many people are accessing the same data, one way

of managing data concurrency is to make each userwait for a turn. The goal of a database managementsystem is to reduce that wait so it is eithernonexistent or negligible to each user.


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Read Consistency

Read consistency, as supported by Oracle, does the

following:..Guarantees that the set of data seen by a statement isconsistent with respect to a single point in time and doesnot change during statement execution (statement-levelread consistency)

..Ensures that readers of database data do not wait forwriters or other readers of the same data

The simplest way to think ofOracle's implementation ofread consistency is to imagine each user operating aprivate copy of the database, hence the multiversion

consistency model. It includes transactions

It even include locking techniques


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Database Security Overview Oracle includes security features that control how a

database is accessed and used Prevent unauthorized database access

Prevent unauthorized access to schema objects

Audit user actions

Database security can be classified into two categories:system security and data security

System security includes the mechanisms that controlthe access and use of the database at the system level

System security mechanisms check whether a user is

authorized to connect to the database, whether databaseauditing is active, and which system operations a usercan perform


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Data security includes the mechanisms that controlthe access and use of the database at the schema

object level. For example, data security includes:

Which users have access to a specific schema objectand the specific types of actions allowed for eachuser on the schema object (for example, user SCOTT

The Oracle server provides discretionary accesscontrol, which is a means of restricting access toinformation based on privileges. The appropriateprivilege must be assigned to a user in order for that

user to access a schema object. Appropriatelyprivileged users can grant other users privileges attheir discretion


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Database Administration Overview

People who administer the operation of an Oracle

database system, known as database administrators

(DBAs), are responsible for creating Oracle

databases, ensuring their smooth operation, and

monitoring their use. Database Backup and Recovery Overview

Oracle uses several structures to provide complete

recovery from an instance or disk failure: the redo

log, undo records, a control file, and databasebackups


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Data Warehousing Overview

A data warehouse is a relational database designed for

query and analysis rather than for transaction processing

It usually contains historical data derived fromtransaction data, but it can include data from othersources. It separates analysis workload from transaction

workload and enables an organization to consolidatedata from several sources

a data warehouse environment includes an extraction,transportation, transformation, and loading (ETL)solution, an online analytical processing (OLAP) engine,client analysis tools, and other applications that managethe process of gathering data and delivering it tobusiness users.


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High Availability Overview

Computing environments configured to provide

nearly full-time availability are known as high

availability systems

When failures occur, the failover process moves

processing performed by the failed component tothe backup component. This process remasters

systemwide resources, recovers partial or failed

transactions, and restores the system to normal,

preferably within a matter of microseconds. Themore transparent that failover is to users, the higher

the availability of the system


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Content Management Overview

Oracle provides a single platform for creating,managing, and delivering personalized, rich content

to any device.

Corporate information assets - documents,

spreadsheets, multimedia, presentations, e-mail, andHTML files - are easily accessible to all users, and

there is no need for specialty servers or unrelated file

systems.

Automatic search capabilities can discover valuablecontent wherever it resides and whatever language it

is in.


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THANK YOU

Documents

Introduction to the Oracle Server