Spatio-temporal databases

NGUYỄN KHẮC TRUNGVĂN ĐÌNH VỸ PHƯƠNGTRƯƠNG VIẾT TOÁNĐÀO THỊ THU TRANG

Advanced Database Systems

2015

Outline

•Part 1: Definition

•Part 2: Spatio - Temporal Data Models

•Part 3: Comparing and Conclusion

•Part 4: Questions & Answers

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Part 1: Definition on spatial-temporal data modeling•A spatiotemporal database is a database that manages both space and time information.•Common examples include:Tracking of moving objects.A database of wireless communication networks

Definition on spatial-temporal data modeling•Spatial-temporal data model are the core of Spatial-Temporal Information System (STIS). They define object data types, relationships, operations and rules to maintain database integrity.•Research both on spatial database and temporal database is basis for spatial-temporal database models.

Temporal semantics•Granularity•Temporal operations•Time density•Representation of time•Transaction / Valid time•Time order•Lifespan

Spatial semantics•Structure of space•Orientation/Direction•Measurement•Topology

The spatial-temporal semantics•Data types•Primitive notions•Type of changes•Evolution in time and space•Space-time topology•Object identities•Dimensionality

Query capabilities•Queries about locations, spatial properties and spatial relationships.•Queries about time, temporal properties and temporal relationships.•Queries about spatio-temporal behaviors and relationships.

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Part 2: Spatio-Temporal Model1. Event-Oriented, 2. Object-Relationship, 3. Object-Oriented, 4. Moving object,5. …

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Part 2: Spatio-Temporal ModelEvent-Oriented

Event Oriented Spatio-Temporal Data Model (ESTDM)

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Part 2: Spatio-Temporal ModelEvent-Oriented

Amendment Vector

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Part 2: Spatio-Temporal ModelObject-Relationship Model (O-R Model)Previous model: • enhanced current GISs realistic worldHowever:• None covered the description of change processes• existing models concern design (rather than:

representation of natural environmental changes, processes and events)

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Part 2: Spatio-Temporal ModelObject-Relationship Model (O-R Model)Different methodologies present: • Modul-R• Mecosig and Pollen• Object-Oriented• Modeling Application Data with Spatio-

temporal features (MADS). implemented following object relationship

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Part 2: Spatio-Temporal ModelObject-Relationship Model (O-R Model)

MADS• incorporates space & time model basics to object-

relationship model• At the same time, the object properties, which are required

to be captured in the spatio-temporaldatabases, are stated. • The processes influencing a single object’s geometry are

described as the characteristic of the geometry attribute• The spatio-temporal processes are visualized through icons

in the schema.

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Part 2: Spatio-Temporal ModelObject-Relationship Model (O-R Model)

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x x x x x

t

t1 t5t4t3t2

S(t1) S(t5)S(t4)S(t3)S(t2)

y y y y y

o2 o2o2 o2

o3 o3 o3o3

o1o1 o1

o1o1

Queryregion Q

Object-Oriented Data Model(O-O Model)

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4 advantages of O-O:

1. A Single Object can represent the whole history of an entity

2. Queries are simple

3. Efficient temporal data handling

4. Uniform treatment of S-T Data handling

Object-Oriented Data Model(O-O Model)

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ST-OBJECT

…….

Worboys ST-object

Spatio

BiTemporal

Object-Oriented Data Model(O-O Model)

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Wachowicz and Healy (version management)ROOT

ST-O

G.To.Th

ST-O

G’.To’.Th’

ST-O

G.To.Th’

Object-Oriented Data Model(O-O Model)

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ST-OBJECT

LAW…….

Bonfatti and Monari (Law)

Rel

Strt

Object-Oriented Data Model(O-O Model)

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Rojas-Vega and Kemp - SIDL

Object-Oriented Data Model(O-O Model)

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Object Model Technique - OMT

Object-Oriented Data Model(O-O Model)

• Its high-level representation abstraction• Representing data varying in 3D space and time

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Object Model Technique - OMT

Object-Oriented Data Model(O-O Model)

STO – Data set

LAW…….

Data set(t)

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Object Model Technique - OMT

Object-Oriented Data Model(O-O Model)

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Object Model Technique - OMT

Object-Oriented Data Model(O-O Model)

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(a) (b) a moving point a moving and shrinking region

y

t

x

y

t

x

Moving Object Data Models

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Moving Object Data Models

• Space vs Time• Position• Extention

Time dimension

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Moving Object Data Models

• Linear • Discrete/continuous• Absolute time model

Time dimension

Captures the change and movement

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Moving Object Data Models

• “slices”• “simple” function

on pair (I, u)

Discrete representation

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Moving Object Data Models

• “slices”• “simple” function

on pair (I, u)

Discrete representation

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Moving Object Data Models

• dynamic attributes

motion vector (with threshold)

speed,acceleration

SpatioTemporal predicates

Part 3: Comparing and Conclusion•Temporal semantic•Spartial semantic•Spartio-temporal semantic•Query capabilities

Temporal•All support multiple granularities (except Moving object)•Assume time order is linear•Earlier: assume discrete modeling of time. Currently: both levels discrete/continuous•Some new models: handling events’ duration and history of ST object (lifespan)

Spatial •Base on spatial data models•Assume vector structure of space (raster is just adopted by 4 models)•Only O-O and Moving Object Orientation and direction of ST object during change/movement across space and time dimensions

support all type of spatial data handling

In spatio-temporalData Model Data types Primitive Notions Types of change Dimensionality

Event Oriented Data, event & raster structures

Event, amendment maps

Only Discrete All

O-R Point, line, region Entity, relationship Not movement All

O-O Simple descriptions, point, line, area

Object, attribute, relationship

All types All

Moving Objects Moving point, region

Sliced representation

All types 2D

Most capture different dimensionality representation of ST-O

Query capability•All models support for attribute and simple queries•Composite query -> describe complex and evolving real work object•Moving object can resolve any type of ST Query

ConclusionsThe reviewed models vary on following features:• Formalisation• Implementation• Tool• Application• Spatial model• Temporal model

Q&Aon the Paper.

Q&ACâu 1: What are talk about of Event-Oriented Model? A. It is easily identify changes or events in data set. B. It uses transaction log to backwards the changes C. It is easily to change the vector-based system D. It uses amendment vector approach and overlay maps

Q&ACâu 2: What is NOT an advantage of using object-oriented approach in STDB?

A. Use multiple objects to represent the whole history of an entity.

B. Uniform treatment of spatial and temporal data handling C. Queries are simple, because they deal with each single object of an entity

D. Efficient temporal data handling

Q&ACâu 3: Moving Object Data Models talk about: A. From an Object to another Object in the time interval B. Attributes of Object can continuously represent by time functions. C. From an Object to another Object by its time functions. D. Temporal part of Object can continuously be recorded.

Q&ACâu 4: Currently, which data model can resolve any type of spatio-temporal query?A. Event Oriented B. Object-Relationship C. Object-Oriented D. Moving object