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Page 1: DBMS Concept

Copyright © 2004 Pearson Education, Inc.

Page 2: DBMS Concept

Copyright © 2004 Pearson Education, Inc.

Chapter 2

Database System Concepts and Architecture

Page 3: DBMS Concept

Slide 2-3Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Data Models

Data Model: Satu set konsep untuk menggambarkan struktur database, dan kendala tertentu yang database harus mematuhi .

Data Model Operations:Operasi untuk menentukan retrievals database dan update dengan mengacu pada konsep dari model data. Operasi pada model data dapat mencakup operasi dasar dan user-defined operasi.

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Slide 2-4Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Categories of data models Konseptual (tingkat tinggi, semantik) model data: Memberikan

konsep-konsep yang dekat dengan cara banyak pengguna melihat data. (Juga disebut entitas-based atau berbasis obyek model data.)

Fisik (rendah-tingkat, internal) model data: Memberikan konsep-konsep yang menggambarkan detail bagaimana data disimpan dalam komputer.

Implementasi model data (representasional): Memberikan konsep-konsep yang jatuh antara dua di atas, menyeimbangkan pandangan pengguna dengan beberapa rincian penyimpanan komputer.

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Slide 2-5Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

History of Data Models Relational Model: proposed in 1970 by E.F. Codd (IBM),

first commercial system in 1981-82. Now in several commercial products (DB2, ORACLE, SQL Server, SYBASE, INFORMIX). Network Model: the first one to be implemented by Honeywell in 1964-65 (IDS System). Adopted heavily due to the support by CODASYL (CODASYL - DBTG report of 1971). Later implemented in a large variety of systems - IDMS (Cullinet - now CA), DMS 1100 (Unisys), IMAGE (H.P.), VAX -DBMS (Digital Equipment Corp.).

Hierarchical Data Model: implemented in a joint effort by IBM and North American Rockwell around 1965. Resulted in the IMS family of systems. The most popular model. Other system based on this model: System 2k (SAS inc.)

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Slide 2-6Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

History of Data Models

Object-oriented Data Model(s): several models have been proposed for implementing in a database system. One set comprises models of persistent O-O Programming Languages such as C++ (e.g., in OBJECTSTORE or VERSANT), and Smalltalk (e.g., in GEMSTONE). Additionally, systems like O2, ORION (at MCC - then ITASCA), IRIS (at H.P.- used in Open OODB).

Object-Relational Models: Most Recent Trend. Started with Informix Universal Server. Exemplified in the latest versions of Oracle-10i, DB2, and SQL Server etc. systems.

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Slide 2-7Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Hierarchical Model

• ADVANTAGES:• Hierarchical Model is simple to construct and operate on• Corresponds to a number of natural hierarchically organized

domains - e.g., assemblies in manufacturing, personnel organization in companies

• Language is simple; uses constructs like GET, GET UNIQUE, GET NEXT, GET NEXT WITHIN PARENT etc.

• DISADVANTAGES:• Navigational and procedural nature of processing• Database is visualized as a linear arrangement of records• Little scope for "query optimization"

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Slide 2-8Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Network Model• ADVANTAGES:

• Network Model is able to model complex relationships and represents semantics of add/delete on the relationships.

• Can handle most situations for modeling using record types and relationship types.

• Language is navigational; uses constructs like FIND, FIND member, FIND owner, FIND NEXT within set, GET etc. Programmers can do optimal navigation through the database.

• DISADVANTAGES:• Navigational and procedural nature of processing• Database contains a complex array of pointers that thread through a

set of records. Little scope for automated "query optimization”

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Slide 2-9Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Schemas versus InstancesDatabase Schema: Skema database: Deskripsi dari

database. Termasuk deskripsi struktur database dan kendala yang harus berpegang pada database.

Skema Diagram (Schema Diagram) : Sebuah tampilan diagram (beberapa aspek) skema database.Skema Bangun: Sebuah komponen dari skema atau objek dalam skema, misalnya, MAHASISWA, KURSUS.

Database Instance: Data aktual yang disimpan dalam database pada saat tertentu dalam waktu. Juga disebut database (atau kejadian).

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Slide 2-10Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Database Schema Vs. Database State

• Basis Data Negara(Database State ): Mengacu pada isi dari database pada saat dalam waktu.

• Negara database awal(Initial Database State ): Mengacu ke database ketika dimuat

• Negara Hari(Valid State ): Sebuah negara yang memenuhi struktur dan kendala dari database.

perbedaannya

• Skema database perubahan yang sangat jarang. • Database state: berubah setiap kali database diperbarui.

• Skema juga disebut kehebatan(intension), sedangkan state disebut extension.

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Slide 2-11Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Three-Schema Architecture

• Proposed to support DBMS characteristics of:• Program-data independence.

• Support of multiple views of the data.

• Usulan untuk mendukung karakteristik DBMS:• Program-data independence.

• Dukungan beberapa pandangan dari data.

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Slide 2-12Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Three-Schema Architecture• Defines DBMS schemas at three levels:

• Internal schema at the internal level to describe physical storage structures and access paths. Typically uses a physical data model.

• Conceptual schema at the conceptual level to describe the structure and constraints for the whole database for a community of users. Uses a conceptual or an implementation data model.

• External schemas at the external level to describe the various user views. Usually uses the same data model as the conceptual level.

• Mendefinisikan skema DBMS pada tiga tingkat:• Skema internal di tingkat internal untuk menjelaskan struktur penyimpanan fisik

dan jalur akses. Biasanya menggunakan model data fisik.• Konseptual skema di tingkat konseptual untuk menggambarkan struktur dan

kendala untuk seluruh database untuk komunitas pengguna. Menggunakan konseptual atau model data pelaksanaan.

• Skema eksternal pada tingkat eksternal untuk menggambarkan pandangan berbagai pengguna. Biasanya menggunakan model data yang sama sebagai tingkat konseptual.

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Slide 2-13Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Three-Schema Architecture

Mappings among schema levels are needed to transform requests and data. Programs refer to an external schema, and are mapped by the DBMS to the internal schema for execution.

Pemetaan antara tingkat-tingkat skema yang diperlukan untuk mengubah permintaan dan data. Program mengacu pada skema eksternal, dan dipetakan oleh DBMS untuk skema internal untuk eksekusi.

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Slide 2-14Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Data Independence

• Logical Data Independence: The capacity to change the conceptual schema without having to change the external schemas and their application programs.

• Physical Data Independence: The capacity to change the internal schema without having to change the conceptual schema.

• Logical data Kemerdekaan: Kapasitas untuk mengubah skema konseptual tanpa harus mengubah skema eksternal dan program aplikasi mereka.

• Data fisik Kemerdekaan: Kapasitas untuk mengubah skema internal tanpa harus mengubah skema konseptual.

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Slide 2-15Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Data Independence

When a schema at a lower level is changed, only the mappings between this schema and higher-level schemas need to be changed in a DBMS that fully supports data independence. The higher-level schemas themselves are unchanged. Hence, the application programs need not be changed since they refer to the external schemas.

Ketika skema di tingkat yang lebih rendah berubah, hanya pemetaan antara skema dan lebih tinggi tingkat skema perlu diubah dalam DBMS yang sepenuhnya mendukung independensi data. Semakin tinggi tingkat skema sendiri tidak berubah. Oleh karena itu, program aplikasi tidak perlu dirubah karena mereka mengacu pada skema eksternal.

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Slide 2-16Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

DBMS Languages• Data Definition Language (DDL): Used by the DBA and database designers

to specify the conceptual schema of a database. In many DBMSs, the DDL is also used to define internal and external schemas (views). In some DBMSs, separate storage definition language (SDL) and view definition language (VDL) are used to define internal and external schemas.

• Data Definition Language (DDL): Digunakan oleh DBA dan desainer database untuk menentukan skema konseptual database. Dalam banyak DBMS, DDL juga digunakan untuk mendefinisikan skema internal dan eksternal (pandangan). Dalam beberapa DBMS, penyimpanan terpisah bahasa definisi (SDL) dan melihat definisi bahasa (VDL) digunakan untuk mendefinisikan skema internal dan eksternal.

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Slide 2-17Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

DBMS Languages

• Data Manipulation Language (DML): Used to specify database retrievals and updates.• DML commands (data sublanguage) can be embedded in a general-

purpose programming language (host language), such as COBOL, C or an Assembly Language.

• Alternatively, stand-alone DML commands can be applied directly (query language).

• Data Manipulasi Language (DML): Digunakan untuk menentukan database dan update retrievals.

• Perintah DML (Data sub-bahasa) dapat tertanam dalam bahasa pemrograman untuk tujuan umum (host language), seperti COBOL, C atau Majelis Bahasa.

• Atau, yang berdiri sendiri perintah DML dapat diterapkan secara langsung (bahasa query).

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DBMS Languages

• High Level or Non-procedural Languages: e.g., SQL, are set-oriented and specify what data to retrieve than how to retrieve. Also called declarative languages.

• Low Level or Procedural Languages: record-at-a-time; they specify how to retrieve data and include constructs such as looping.

• Tingkat Tinggi atau Non-prosedural Bahasa: misalnya, SQL, adalah set-oriented dan menentukan apa data untuk mengambil dari bagaimana untuk mengambil. Juga disebut bahasa deklaratif.

• Tingkat rendah atau Bahasa Prosedural: catatan-di-waktu-, mereka menentukan bagaimana untuk mengambil data dan termasuk konstruksi seperti perulangan.

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Slide 2-19Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

DBMS Interfaces• Stand-alone query language interfaces.• Programmer interfaces for embedding DML in programming languages:

• Pre-compiler Approach/Pendekatan• Procedure (Subroutine) Call Approach

• User-friendly interfaces:• Menu-based, popular for browsing on the web• Forms-based, designed for naïve users• Graphics-based (Point and Click, Drag and Drop etc.)• Natural language: requests in written English• Combinations of the above

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Other DBMS Interfaces

• Speech as Input (?) and Output• Web Browser as an interface• Parametric interfaces (e.g., bank tellers) using

function keys.• Interfaces for the DBA:

• Creating accounts, granting authorizations

• Setting system parameters

• Changing schemas or access path

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Slide 2-21Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

Copyright © 2004 Pearson Education, Inc.

Database System Utilities• To perform (tugas dan fungsi)certain functions

such as:• Loading data stored in files into a database. Includes

data conversion tools.• Backing up the database periodically on tape.• Reorganizing database file structures.• Report generation utilities.• Performance monitoring utilities.• Other functions, such as sorting, user monitoring, data

compression, etc.

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Slide 2-22Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

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Other Tools• Data dictionary / repository:

• Used to store schema descriptions and other information such as design decisions, application program descriptions, user information, usage standards, etc.

• Active data dictionary is accessed by DBMS software and users/DBA.• Passive data dictionary is accessed by users/DBA only.

• Data dictionary / repository:Digunakan untuk menyimpan deskripsi skema dan informasi lain seperti keputusan desain, deskripsi program aplikasi, informasi pengguna, standar penggunaan, dll

• Kamus data aktif diakses oleh DBMS perangkat lunak dan pengguna / DBA.

• Pasif kamus data diakses oleh pengguna / DBA hanya• Application Development Environments and CASE (computer-aided

software engineering) tools:• Examples – Power builder (Sybase), Builder (Borland)

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Slide 2-23Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

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Centralized and Client-Server Architectures

• Centralized DBMS: combines everything into single system including- DBMS software, hardware, application programs and user interface processing software.

• Sentralisasi DBMS: menggabungkan semuanya ke dalam sistem tunggal termasuk-DBMS software, hardware program aplikasi, dan pengguna perangkat lunak antarmuka pengolahan

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Slide 2-24Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

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Basic Client-Server Architectures

• Specialized Servers with Specialized functions• Clients

• DBMS Server

• Server khusus dengan fungsi khusus

• klien

• DBMS Server

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Specialized Servers with Specialized functions:

• File Servers

• Printer Servers

• Web Servers

• E-mail Servers

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Clients: • Provide appropriate interfaces and a client-version of the system to access and

utilize the server resources. • Clients maybe diskless machines or PCs or Workstations with disks with only

the client software installed.• Connected to the servers via some form of a network.

(LAN: local area network, wireless network, etc.)• Menyediakan antarmuka yang sesuai dan klien-versi sistem untuk

mengakses dan memanfaatkan sumber daya server.

• Klien mungkin mesin diskless atau PC atau Workstation dengan disk dengan hanya perangkat lunak klien diinstal.

• Terhubung ke server melalui beberapa bentuk jaringan. (LAN: jaringan area lokal, jaringan nirkabel, dll)

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Slide 2-27Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition

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DBMS Server

• Provides database query and transaction services to the clients

• Sometimes called query and transaction servers• Menyediakan query database dan layanan

transaksi kepada klien

• Kadang-kadang disebut query dan transaksi server

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Two Tier Client-Server Architecture

• User Interface Programs and Application Programs run on the client side• Interface called ODBC (Open Database Connectivity – see Ch 9) provides

an Application program interface (API) allow client side programs to call the DBMS. Most DBMS vendors provide ODBC drivers.

• User Interface Program dan Program Aplikasi berjalan di sisi klien

• Antarmuka yang disebut ODBC (Database Connectivity Terbuka - lihat Bab 9) menyediakan program aplikasi antarmuka (API) memungkinkan klien untuk memanggil program sisi DBMS. Kebanyakan DBMS vendor menyediakan driver ODBC.

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Two Tier Client-Server Architecture

• A client program may connect to several DBMSs.• Other variations of clients are possible: e.g., in some DBMSs, more

functionality is transferred to clients including data dictionary functions, optimization and recovery across multiple servers, etc. In such situations the server may be called the Data Server.

• Sebuah program klien dapat terhubung ke beberapa DBMS.

• Variasi lain dari klien yang mungkin: misalnya, dalam beberapa DBMSs, fungsionalitas lebih ditransfer ke klien termasuk fungsi kamus data, optimasi dan pemulihan di beberapa server, dll Dalam situasi seperti server dapat disebut Data Server.

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Three Tier Client-Server Architecture

• Common for Web applications• Intermediate Layer called Application Server or Web Server:

• stores the web connectivity software and the rules and business logic (constraints) part of the application used to access the right amount of data from the database server

• acts like a conduit for sending partially processed data between the database server and the client.• Additional Features- Security:

• encrypt the data at the server before transmission• decrypt data at the client

• Umum untuk aplikasi Web

• Lapisan intermediate yang disebut Application Server atau Server Web:

• toko perangkat lunak konektivitas web dan aturan-aturan dan logika bisnis (kendala) bagian dari aplikasi yang digunakan untuk mengakses jumlah yang tepat data dari database server

• bertindak seperti saluran untuk mengirim data sebagian diproses antara database server dan klien.

• Tambahan Fitur-Keamanan:

• mengenkripsi data pada server sebelum transmisi

• mendekripsi data pada klien

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Classification of DBMSs

• Based on the data model used:• Traditional: Relational, Network, Hierarchical.• Emerging: Object-oriented, Object-relational.

• Other classifications:• Single-user (typically used with micro-

computers) vs. multi-user (most DBMSs).• Centralized (uses a single computer with one

database) vs. distributed (uses multiple computers, multiple databases)

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Classification of DBMSs

Distributed Database Systems have now come to be known as client server based database systems because they do not support a totally distributed environment, but rather a set of database servers supporting a set of clients.

Sistem Basis Data Terdistribusi kini telah dikenal sebagai sistem database berbasis client server karena mereka tidak mendukung lingkungan yang sama sekali didistribusikan, melainkan satu set database server mendukung satu set klien.

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Variations of Distributed Environments:

• Homogeneous DDBMS

• Heterogeneous DDBMS

• Federated or Multidatabase Systems