BTE 423 Chapter 1
File
collection of records
Metadata
data that describes the objects in the database and makes it easier for those objects to be accessed or manipulated.
External/conceptual mapping
this mapping enables the DBMS to map names in the user's view to the relevant part of the conceptual schema.
Authorization control
to confirm whether the user has the necessary permission to carry out the required operation.
Data manipulation Language (DML)
users use this to insert, update, delete, and retrieve data from the database. Having a central repository for all data and data descriptions allows the DML to provide a general inquiry facility to the data called the query language
The limitations of the file-based approach can be attributed to two factors
1. The definition of the data is embedding in the application programs, rather than being stored separately and independently 2. There is no control over the access and manipulation of data beyond that imposed by the application programs
Multi-tenet
DB that has shared server from one or multiple orgs
Components of a DBMS
DBMS partitioned into several software components called modules where each is assigned a specific operation; The DBMS interfaces with other software components such as user queries and access methods
Functions of a DBMS
Data storage, retrieval, and update, user-accessible catalog, transaction support, concurrency control services, recovery services, authorization services, support for data communication, integrity services, services to promote data independence, utility services
Three service models of cloud computing
SaaS, PaaS, IaaS
Limitations of file-based system
Separation of isolation of data, duplication of data, data dependence, incompatible file formats, fixed queries
the database management system
Software that interacts with the users' application programs.
Data Definition Language
The DDL allows users to specify the data types and structures and the constraints on the data to be stored in the database
Conceptual level
The community view of the database. This level describes what data is stored in the database and the relationships among the data. It provides the mapping and the desired independence between the external and internal levels. It represents all entities and their attributes and relationships; the constraints on the data; semantic info about the data; security and integrity information
Internal level
The physical representation of the database on the computer. This level describes how the data is stored in the database. The way the DBMS and the operating system perceive the data and where the data is actually stored using the data structures and file organizations
Entities
[Staff, PropertyforRent, PrivateOwner, Client]
Service oriented architecture (SOA)
a business-centric software for building applications that implement business processes as sets of services published at a granularity relevant to the service consumer. Services can be invoked, published, and discovered and are abstracted away from the implementation using a single standards-based form of interface
Distributed processing
a centralized database that can be accessed over a computer network
File based system
a collection of application programs that preform services for the end-users, such as the production of reports. Each program defines and manages its own data.
Database
a collection of related data
Data warehouse
a consolidated/integrated view of corporate data drawn from disparate operational data sources and a range of end-user access tools capable of supporting simple to highly complex queries to support decision making
entity
a distinct object in the organization that is to be represented in the database
Entity
a distinct object like a person place or thing
Data definition language (DDL)
a language that allows the DBA or user to describe and name the entities, attributes, and relationships required for the application together with any associated integrity and security constraints
Nonprocedural DML
a language that allows the user to state what data is needed rather than how it is to be retrieved
Procedural DML
a language that allows the user to tell the system what data is needed and exactly how to retrieve the data
Distributed database
a logically interrelated collection of shared data (and a description of this data) physically distributed over a computer network
Structured Query Language (SQL)
formal and defacto language.
Cloud computing
a model for enabling ubiquitous convenient on demand network access to a shared pool of configurable computer resources (eg networks, servers, storage, applications and services)
Database application
a program that interacts with the database at some point in its execution
attribute
a property that describes some aspect of the object that we wish to record
Web service
a software system designed to support interoperable machine-to-machine interaction over a network
Query language
alleviates the problems with file based systems.
Attributes
also called fields, are in tables. For ex. PropertyForRent can have fields like propertyNo, rent, city
External schema
also called subschemas that correspond to different views of the data.
Enterprise resource planning (ERP)
an application layer built on top of a DBMS that integrates all the business functions of an organization.
relationship
an association between entities
Relationship
an association between the two entities.
Data model
an integrated collection of concepts for describing and manipulating data, relationships between data, and constraints on the data in an organization. Has three components, a structural part, manipulative part, and a set of integrity constraints
Components of the database manager
authorization control, command processor, integrity checker, query optimizer, transaction manager
Relational data model
based on the concept of mathematical relations. Here data and relationships are represented as tables.
Relationships
between these entities [Staff Manages PropertyforRent]
Hybrid cloud
cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community or public) that remain unique entities but are bound together by standardized or proprietary tech
Public cloud
cloud infrastructure is made available to the public by a service provider. These services are free or offered on a pay-per-use model. It may be owned and manage by a business, academic, or government org
Private cloud
cloud infrastructure is operated solely for a single organization whether managed internally by the org, a third party, or some combination of them
Community cloud
cloud infrastructure is shared for exclusive use by a specific community of orgs that have common concerns (ie security) and may be hosted internally or externally
Resource managers
complex apps are usually built on top of several resource managers such as DBMSs, OSs, user interfaces.
Disadvantages of DBMSs
complexity, size, cost of DBMSs, additional hardware costs, cost of conversion, performance, greater impact of a failure
Three level architecture
comprised of an external, a conceptual and an internal level
Structural part
consists of a set of rules according to which databases can be constructed
Advantages of DBMs
control of data redundancy, economy of scale, data consistency, balance of conflicting requirements, more information from the same amount of data, improved data accessibility and responsiveness, sharing of data, increased productivity, improved security, increased concurrency, improved data integrity, improved maintenance through data independence, enforcement of standards, improved backup and recovery services
DML Preprocessor
converts DML statements embedded in an application program into standard function calls in the host language. The DML preprocessor must interact with the query procerrir to generate the appropriate code
DDL compiler
converts the DDL statements into a set of tables containing metadata. These tables are then stored in system catalog while control information is sorted in data file headers
Benefits of cloud computing
cost reduction, scalability/agility, improved security, reliability, access to new tech, faster dev, large scale prototyping, more flexible work practices, increased competitiveness
Manipulative part
defining the types of operation that are allowed on the data
Conceptual schema
describes all the entities, attributes, and relationships together with integrity constraints.
Attributes
describing properties or qualities of each entity (for example, each Staff entry has a name, position and salary)
Query optimizer
determines an optimal strategy for the query execution. Finds best way of getting data to you
Fields
each record contains a logical set of one or more fields
Scheduler
ensures that concurrent operations on the database proceed without conflicting with one another. It controls the relative order in which transaction operations are executed.
Integrity checker
ensures that requested operation satisfies all necessary integrity constraints (eg key constraints) for an operation that changes the database. Will make sure things aren't doubled
Set of integrity constraints
ensures that the data is accurate.
Recovery manager
ensures that the database remains in a consistent state in the presence of failures. It is responsible for transaction commit and abort
Tables
files in a schema which have attributes (PropertyForRent, PrivateOwner, Client, Lease)
middleware
generic term used to describe software that mediates with other software and allows for communication disparate applications in a heterogeneous system.
Application server
hosts an application programing interface (API) to expose business logic and business processes for use by other applications.
Database design
how the structure of the database is determined. The org must think of the data first and the application second. This is called the paradigm shift.
Application programs
how users interact with the database and can generate and maintain information.
Database manager (DM)
interfaces with user submitted application programs and queries. The dm examines the external and conceptual schemas to determine what conceptual records are queried to satisfy the request. The dm then places a call to the filemanager to perform the request
Logically related data
is contained in files
Data Manipulation Language (DML)
language that provides a set of operations to support the basic data manipulation operations on the data held in the database. Usually includes insertion of new data, modification of data stored, retrieval of data contained, deletion of data
Query processor
major DBMS component that transforms queries into a series of low-level instructions directed to the database manager
Data independence
major objective for the three-level architecture which means that upper levels are unaffected by changes to lower levels. Two kinds, logical and physical
File manager
manipulates the underlying storage files and managers the allocation of storage space on disk. It establishes and maintains the list of structures and indexes defined in the internal schema
Physical level
may be managed by the operating system under the direction of DBMS.
Risks of cloud computing
network dependency, system dependency, cloud provider dependency, lack of control, lack of transparency
DBaaS
offers full database functionality to application developers. A management layer is responsible for the continuous monitoring and configuring of the database to achieve optimized scaling
DaaS
offers the ability to define data in the cloud and subsequently query that data on demand
Command processor
on confirmation of user authority, control is passed to the command processor
Five essential characteristics of cloud computing
on demand service, broad network service, resource pooling, rapid elasticity, measured service
data abstraction
one advantage of this that we can change the internal definition of an object without affecting the users in the object, provided that the external definition remains the same in the same way, the database approach separates the structure of the data from the application programs and stores it in the database
system catalogue
or data dictionary or metadata - this is the description. It is the self-describing nature of a database that provides program-data independence
Database schema
overall description of the database
Transaction manager
performs the required processing of operations that it receives from transactions
Four main deployment models of cloud computing
private, community, public, hybrid
TP Monitor
program that controls data transfers between clients and servers in order to provide a consistent environment, particularly for online transaction processing
Attribute
property that describes some aspect of the object that we wish to record
Database system
the collection of application programs that interact with the database along with the DBMS and the database itself
Server
provides some resource; Accepts and processes database requests from clients; Checks authorization; Ensures integrity constraints not violated; Performs query/update processing and transmits response to client; Maintains system catalog, provides concurrent database access, provides recovery control
Procedures
refer to the instructions and rules that govern the use of the database. Like how to log on, how to make backups
second-generation DBMSs
relational DBMSs
Client
requires some resource; Managers user interface; Accepts and checks syntax of user input; Processes application logic; Generates database requests and transmits to server; Passes response back to user
Buffer manager
responsible for the transfer of data between main memory and secondary storage
Intension
sometimes the schema is called this, an instance is called an extension or state of the database
data warehouses
specialized DBMSs which can store data drawn from several data sources.
Database schema
specified during the database design process and is not expected to change frequently
View mechanism
the DBMS provides this, it is a facility which allows each user to have his or her own view of the database. A view is a subset of the database.
semantic data modeling
the attempts to provide a data model that represents the real world more closely
Database insurance
the data in the database at any particular point in time. Therefore, many database instances can correspond to the same database scheme
Physical data independence
the immunity of the conceptual schema to changes in the internal schema
Logical data independence
the immunity of the external schemas to changes in the conceptual schema
Internal schema
the lowest level of abstraction, this is a complete description of the internal model, containing the definitions of stored records, the methods of representation, the data fields, and the indexes and storage structures used.
Conceptual/internal mapping
the mapping enables the DBMS to find the actual record or combo of records in physical storage that constitutes a logical record
Data Base Task Group (DBTG) three components
the network schema: the logical organization of the entire database, the subschema: the part of the database as seen by the user or application program, data management language to define the data characteristics
Conceptual modeling or conceptual database design
the process of constructing a model of the information use in an enterprise that is independent of implementation details, such as the target DBMS, application programs, programming languages, or any other physical considerations. This model is called a conceptual data model
System catalog
the result of the compilation of the DDL statements is a set of tables in special files collectively called the system catalog. Integrates metadata
Distributed DBMS (DDBMS)
the software system that permits the management of the distributed database and makes the distribution transparent to users. Has the following characteristics; A collection of logically related shared data; data split into a number of fragments; fragments may be replicated; fragments/replicas are allocated to sites; sites are linked by a communications network; data at each site is under control of a DBMS; DBMS at each site can handle local applications autonomously; Each DBMS participates in at least one global application
Database management system (DBMS)
the software that manages and controls access to the database
Schema
the structure of the database. Is consisted of tables or files
External level
the way users perceive the data. The users' view of the database. This level describes that part of the database that is relevant to each user.
