Flashcards
Database Management 2
Flashcards do conjunto (33)
- 1Attribute, or set of attributes, within one relation that matches candidate key of some (possibly same) relation.Foreign Key
- 2– Represents value for an attribute that is currently unknown or not applicable for tuple. – Deals with incomplete or exceptional data. – Represents the absence of a value and is not the same as zero or spaces, which are values.Null
- 3Entity Integrity – In a base relation, no attribute of a primary key can be..........null
- 4Referential Integrity – If foreign key exists in a relation, either foreign key value must ......or foreign key value must be ......match a candidate key value of some tuple in its home relation
wholly null. - 5Named relation corresponding to an entity in conceptual schema, whose tuples are physically stored in database.Base Relation
- 6– Dynamic result of one or more relational operations operating on base relations to produce another relation.View
- 7A virtual relation that does not necessarily actually exist in the database but is produced upon request, at time of request.Views
Contents of a view are defined as a query on one or more base relations.
◆ Views are dynamic, meaning that changes made to base relations that affect view attributes are immediately reflected in the view. - 8There are restrictions on types of modifications that can be made through views: – Updates are allowed if query ....... and contains a ........ – Updates are not allowed involving .... – Updates are not allowed involving aggregation ....involves a single base relation
candidate key of base relation.
multiple base relations.
or grouping operations. - 9Classes of views are defined as: –theoretically not updateable;
– theoretically updateable;
– partially updateable. - 10Multi-user DBMS Architectures ◆ File-server architecture – Processing is distributed about the network – Three main disadvantages » Large amount of ..... » Full copy .... » Concurrency, recovery, and integrity control ..... ◆ Multiple DBMSs can access the ...network traffic
of DBMS required on each workstation
are complex
same files - 11Traditional two-tier client–server architecture – Client process requires ... – Server provides... – Basic separation of ..... – Typical interaction between client and serversome resource
the resource
four main components of business application - 12Three-tier client–server architecture – User.... – Business logic and.... – DBMS – Many advantages over traditional two-tier or single-tier designsinterface layer
data processing layer - 13Application servers – Hosts an application programming interface (API) to......expose business logic and business processes for use by other applications
- 14Middleware – Software that mediates with other software . Communication among disparate applications – Six main types » Asynchronous.....(RPC) » ..... RPC »..../Subscribe » .......(MOM) » .........(ORB) » SQL-oriented data accessRemote Procedure Call
Synchronous
Publish
Message-Oriented middleware
Object-request broker - 15Transaction processing monitor – Controls data transfer between clients/servers – Provides a consistent environment, particularly for online transaction processing (OLTP) – Significant advantages »...... routing »..... transactions » Load..... » Funneling » Increased.....Transaction
Managing distributed
balancing
reliability - 16– ......... -Architecture for building applications that implement business processes as sets of services – Published at a granularity relevant to the service consumer – Loosely coupled and autonomous servicesService-Oriented Architectures (SOA)
- 17Logically interrelated collection of shared data physically distributed over a computer networkDistributed database
- 18Software system that permits the management of the distributed database – Makes the distribution transparent to usersDistributed DBMS
- 19Characteristics of DDBMS – Collection of .......shared data – Data split into...... –..... may be replicated – .....are allocated to sites – Sites are linked by a ...... – Data at each site is controlled by DBMS – DMBS handles local apps autonomously – Each DBMS in one or more global applogically related
fragments
Fragments
Fragments/replicas
communications network - 20........... – Centralized database that can be accessed over a computer network ◆ System consists of data that is physically distributed across a number of sites in the networkDistributed processing
- 21.............. – Consolidated/integrated view of corporate data – Drawn from disparate operational data sources – Range of end-user access tools capable of supporting simple to highly complex queries to support decision making – Subject-oriented, integrated, time-variant, and nonvolatileData warehouse
- 22Major components of a DBMS: –Query processor
– Database manager (DM)
– File manager
– DML preprocessor – DDL compiler
– Catalog manager - 23Major software components for database manager –Authorization control – Transaction manager
– Command processor – Integrity checker
– Query optimizer
– Scheduler
– Recovery manager – Buffer manager - 24Cloud Computing – Key Characteristics*Resource pooling
– Provider’s computing resources are pooled to serve multiple consumers, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. Examples of resources include storage, processing, memory, and network bandwidth.
Rapid elasticity
– caters for customer’s spikes in demand and reduces risk of outages and service interruptions. Capacity can be automated to scale rapidly based on demand.
Measured service
– uses a metering capability to measure usage of service (e.g. storage, processing, bandwidth, and active user accounts). - 25Cloud Computing – Service ModelsSoftware as a Service (SaaS):
– Software and data hosted on cloud. Accessed through using thin client interface (e.g. web browser). Consumer may be offered limited user specific application configuration settings.
– Examples include Salesforce.com sales management applications, NetSuite’s integrated business management software, Google’s Gmail and Cornerstone OnDemand.
Platform as a Service (PaaS)
Allows creation of web applications without buying/maintaining the software and underlying infrastructure. Provider manages the infrastructure including network, servers, OS and storage, while customer controls deployment of applications and possibly configuration.
– Examples include Salesforce.com’s Force.com, Google’s App Engine, and Microsoft’s Azure.
Infrastructure as a Service (IaaS)
– Provider’s offer servers, storage, network and operating systems – typically a platform virtualization environment – to consumers as an on-demand service, in a single bundle and billed according to usage.
– A popular use of IaaS is in hosting websites. Examples Amazon’s Elastic Compute Clo - 26Benefits of Cloud ComputingCost-Reduction: Avoid up-front capital expenditure.
◆ Scalability/Agility: Organisations set up resources
on an as-needs basis.
◆ Improved Security: Providers can devote expertise & resources to security; not affordable by customer.
◆ Improved Reliability: Providers can devote expertise & resources on reliability of systems; not affordable by customer.
◆ Access to new technologies: Through use of provider’s systems, customers may access latest
technology.
Faster development: Provider’s platforms can provide many of the core services to accelerate development cycle.
◆ Large scale prototyping/load testing: Providers have the resources to enable this.
◆ More flexible working practices: Staff can access files using mobile devices.
◆ Increased competitiveness: Allows organizations to focus on their core competencies rather than their IT infrastructures. - 27Risks of Cloud ComputingNetwork Dependency: Power outages, bandwidth issues and service interruptions.
◆ System Dependency: dependency on availability and reliability of provider’s systems.
◆ Cloud Provider Dependency: Provider could became insolvent or acquired by competitor, resulting in the service suddenly terminating.
Lack of control: Customers unable to deploy technical or organisational measures to safeguard the data. May result in reduced availability, integrity, confidentiality, intervenability and isolation.
◆ Lack of information on processing transparency - 28As a type of Software as a Service (SaaS), cloud-based database solutions fall into two basic categories:... Key difference between the two options is mainly how the data is managed.Data as a Service (DaaS), and – Database as a Service (DBaaS)
- 29Offers full database functionality to application developers.Database as a Service (DBaaS)
- 30Provides a management layer that provides continuous monitoring and configuring of the database to optimized scaling, high availability, multi-tenancy (that is, serving multiple client organizations), and effective resource allocation in the cloud, thereby sparing the developer from ongoing database administration tasks.Database as a Service (DBaaS)
- 31Services enables data definition in the cloud and subsequently querying. – Does not implement typical DBMS interfaces (e.g. SQL) but instead data is accessed via common APIs. –– Data as a Service (DaaS)
- 32Enables organization with valuable data to offer access to others. Examples Urban Mapping (geography data service), Xignite (financial data service) and Hoovers (business data service.)– Data as a Service (DaaS)
- 33—
Informações
- Descrição
- data science (DataBase Management Systems) FlashCards sobre Database Management 2 , criado por amanda morrow em 07-05-2017.
- Criado por
- amanda morrow
- Visualizações
- 13
- Avaliação