Spatial and Temporal Data and Mobility

Spatial and Temporal Data and Mobility

1. Motivation

   • Historical information can be incorporated manually into a schema design.
   • Spatial data. Spatial data include geographic data,suchasmapsandassociated information, and computer-aided-design data,suchasintegratedcircuit designs or building designs.
   • The main distinguishing feature of video and audio data is that the display of the data requires retrieval at a steady, predetermined rate; hence, such data are called continuous-media data.
   • Mobile databases. such as laptop and netbook computers and high-end cell phones that are connected to base stations via wireless digital communication networks.

2. Time in Databases

   • A database models the state of some aspect of the real world outside itself.
   • databases model only one state—the current state— of the real world, and do not store information about past states, except perhaps as audit trails.
   • system may store information about current and past readings of sensors in the factory, for analysis.
   • To simplify the representation, each tuple has only one time interval associated with it
   • implementation would have a structured type, perhaps called Interval,thatcontains both fields.

3. Spatial and Geographic Data

   • Computer-aided-design (CAD)data, which includes spatial information about how objects—such as buildings, cars, or aircraft— are constructed
   • Geographic information systems are special-purpose databases tailored for storing geographic data.
   • Computer-aided-design (CAD) systems traditionally stored data in memory during editing or other processing, and wrote the data back to a file at the end of a session of editing.
   • The drawbacks of such a scheme include the cost of transforming data from one form to another, and the need to read in an entire file even if only parts of it are required.
   • Geographic data are spatial in nature, but differ from design data in certain ways.
   • Raster data. Such data consist of bit maps or pixel maps, in two or more dimensions.
   • Vector data are constructed from basic geometric objects, such as points, line segments, polylines, triangles, and other polygons in two

4. Multimedia Databases

   • One approach to building a database for such multimedia objects is to use databases for storing the descriptive attributes and for keeping track of the files in which the multimedia objects are stored.
   • The database must support large objects, since multimedia data such as videos can occupy up to a few gigabytes of storage. Many database systems do not support objects larger than a few gigabytes.
   • The retrieval of some types of data, such as audio and video, has the requirement that data delivery must proceed at a guaranteed steady rate
   • Data must be delivered sufficiently fast that no gaps in the audio or video result.
   • Video server. Multimedia data are stored on several disks (usually in a RAID configuration)
   • People view multimedia data through various devices, collectively referred to as terminals.

5. Mobility and Personal Databases

   • The widespread use of laptop, notebook, or netbook computers.
   • The widespread use of cell phones with the capabilities of a computer.
   • Large-scale, commercial databases have traditionally been stored in central computing facilities
   • The route between a pair of hosts may change over time if one of the two hosts is mobile.
   • User time is a highly valuable commodity in many business applications.
   • Mobile computers without wireless connectivity are disconnected most of the time when they are being used, except periodically when they are connected
   • The version-vector scheme detects inconsistencies when copies of a document are independently updated.

6. Nombre: Juan Manuel Figueroa Solís Carnet: 2018139700 Universidad: I.T.C.R Curso: IC4302 Bases de Datos 2 Fecha: 28/10/21 Profesor: Erick Hernández Bonilla Grupo: 40

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