location-aware computing · 2019. 10. 17. · spatial database: modeling and implementation with...

Location-aware Computing Spatial Databases: POSTGIS

Prof. Marco Di Felice Department of Computer Science and Engineering

University of Bologna

Context Aware Systems

http://www.cs.unibo.it/difelice/

Location-aware services

2

COMPONENTSofLOCATION-BASEDSERVICESARCHITECTURE

Source:http://geoawesomeness.com/

WewillconsiderDBMSforLocationbasedServiceandContent

Providers

SPATIALDATABASE:MODELINGANDIMPLEMENTATIONWITHPOSTGISMARCODIFELICE

Location-aware services

3

GeoDataACQUISITION


GeoDataMODELING

GeoDataSTORAGE

GeoDataVISUALIZATION

GeoDataAnalytics

Database Management Systems (DBMS)

4SPATIALDATABASE:MODELINGANDIMPLEMENTATIONWITHPOSTGIS

MARCODIFELICE

² DATABASEMANAGEMENTSYSTEMS(DBMS)²  Softwaresystemthatisabletomanagedatacollections:large,

sharedandpersistent,inasecureandefficientway.²  AhomogeneousdatacollectionwhichismanagedbyaDMBS

iscalleddatabase(e.g.databaseofstudentsatUNIBO).Ø  Datamodeling,accordingtoalogicdatamodelØ  Dataaccessandcreate/read/write/update(CRUD)operationsØ  DataproceduresandtriggersØ  Datasharingamongmultipleusers/applicationsØ  DataencryptionanddataaccessprotectionØ  DatashardinginnetworkeddistributeddeploymentsØ  …

COMMONOPERATIONS

DBMS: Characteristics

5

ConcurrencyEfficiency

DBMS

Reliability Security


Spatial DBMS


MARCODIFELICE

² ASpatialDatabaseManagementSystem(SDBMS)maybedefinedasaDBMSthatoffersspatialdatatypesinitsdatamodelandquerylanguage,andsupportsspatialdatatypesinitsimplementation[1].

[1]http://www.geol-amu.org/notes/m14b-4-4.htm

1.SDBMSsprovidenewdatatypesinordertomodelsome

geospatialfeatures.

https://do

cs.oracle.com/


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2.SDBMSsprovidespatialjoinsandspatialquery

methods.

Relationshipsbetweendataobjects

[2]DavidBlasby,POSTGIStutorial,BuildingaSpatialDatabaseinPostgreSQL

Spatial Relationships

Distance between a toxic waste dump and a piece of property you were considering buying.

SINGLEDISTANCE

Source:[2]

Spatial DBMS


Distance to various pubs8






MULTI-DISTANCE

Source:[2]


methods.

Spatial DBMS


Adjacency: All the lots which share an edge9






ADJACENCY

Source:[2]


methods.

Spatial DBMS


MARCODIFELICE





Source:[2]

Connectivity: Tributary relationships in river networks

CONNECTIVITY 2.SDBMSsprovidespatialjoinsandspatialquery

methods.

Spatial DBMS


MARCODIFELICE




R-TREE3.SDBMSsprovidespatial

indexingfordatamanagementandqueryoptimization

https://do

cs.oracle.com/

Spatial DBMS


MARCODIFELICE

SpatialDatabaseManagementSystems(SDBMSs)

NativeSDBMS GenericDBMSwithSpatialExtensions

²  SmallWorld ² OracleSpatial² MySQLGIS² PostGIShttps://seekingalpha.com

Spatial DBMS

Spatial DBMS: PostGIS


MARCODIFELICE

² Postgres(QL)https://www.postgresql.org²  Open-sourceRelationalDBMS(RDBMS)²  Firstversionsreleasedin1990(1996withthisname)bya

teamofBerkeley(US)graduatestudents²  Transactional,ACID-compliant²  PL/pgSQLproceduralprogramminglanguage²  Replicationsupportindistributedenvironments²  Client-serverarchitecture²  …

DBMS: Data Modeling

14

² OriginallyproposedbyE.Coddin1969.² DMBSsupportingtherelationalmodelarealsoknownasRDBMS.² Largelythemostuseddatamodellingapproach.² Basedonnotionsofrelationalalgebra.² SQLàProgramminglanguagesupporting/implementingthemodel.

RELATIONALMODEL

² Dataitemsarestructuredasfixedlengthrecords,andgroupedintocollectionsoflogical-relatedinformationcalledtables.

INFORMALDEFINITION


DBMS: Data Modeling

15

Name Code Lecturer

Databasesystems 0121 A.York

Networksecurity 1213 M.Write

MachineLearning 1455 R.Penrose

q Columnsofthetable(Propertiesofinterest)àAttributesq Headerofthetable(i.e.nameofthetable+nameoftheattributes)àSchemaq RowsàInstancesofthetable


COURSES


DBMS: Data Modeling

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²  Tablesandrelations²  NULLvalues²  Primarykey²  Foreignkey²  Normalforms²  …

MAINELEMENTSOFTHERELATIONALMODEL

DBMS: Data Modeling

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² StructuredQueryLanguage(SQL)àProgramminglanguageusedbyDBMSbasedontherelationaldatamodel(RBDMS).

Name Code LecturerCode

Databasesystems 0121 00

Networking 1213 01

Security 1455 02

COURSES

SELECTLECTURERCODEFROMCOURSESWHEREName=“Networking”

RetrievethecodeofthelecturerwhoisteachinganyNetworkingcourse

SQLCODE

01


18

² POSTGISàSpatialdatabaseextenderforthePostgreSQLDBMS.²  StartedasaprojectofRefractionsResearch.²  Adoptedandimprovedonbygovernments,public

organizationsandprivatecompanies.²  UndertheumbrellaoftheOpenSourceGeospatial

Foundation(OSGeo).


CREATEDATABASEpostgis_trial;CREATEEXTENSIONpostgis;



MARCODIFELICE

PostGISinAction,SecondEditionReginaO.ObeandLeoS.Hsu

April2015ISBN9781617291395ManningEdition

Aquitecompletereference…



MARCODIFELICE

POSTGIScomponentsinthistutorial² SpatialDataTypes² Creatingnewgeometry/geographicdata² Geometryrelationshipsandgeo-queries²  Importingandexportingspatialdata² POSTGISviewingtools² Spatialindexing



MARCODIFELICE

POSTGISoffersfourmainspatialtypes

²  GeometryàplanartypebasedonCartesianmath(elements:points,lines,polygons,…).

²  Geographyàspheroidalgeodetictype(linesandpolygonsaredrawnonacurvedsurface).

²  Topologyàrelationalmodeltype.Objectsarerepresentedasanetworkofnodesandedges.

²  Rasteràspaceismodeledasagridofrectangularcells,eachcontaininganumericvalue.



MARCODIFELICE

Geometry/geographysubtypes² Thesimplestgeometrysubytpe:Points

CREATETABLEmyPoints(idSERIALPRIMARYKEY,descriptionVARCHAR(10),pointGEOMETRY(POINT),3dpointGEOMETRY(POINTZ),pointsrdGEOMETRY(POINT,4326)

);



MARCODIFELICE

Geometry/geographysubtypes² Thesimplestgeometrysubytpe:Points

Ø  POINTàapointinthe2Dspacewith(X,Y)coordinatesØ  POINTZàapointinthe3Dspacewith(X,Y,Z)coordinatesØ  POINTMàapointinthe2Dspacewithameasuredvalue(M)Ø  POINTZMàapointinthe3Dspacewithameasuredvalue(M)



MARCODIFELICE

Geometry/geographysubtypesLINESTRINGLINESTRINGZLINESTRINGMLINESTRINGZMPOLYGONMULTIPOINTMULTIPOLYGONGEOMETRYCOLLECTION

CREATETABLEgeometries(namevarchar,geomgeometry);INSERTINTOgeometriesVALUES('Point','POINT(00)'),('Linestring','LINESTRING(00,11,21,22)'),('Polygon','POLYGON((00,10,11,01,00))'),('PolygonWithHole','POLYGON((00,100,1010,010,00),(11,12,22,21,11))'),('Collection','GEOMETRYCOLLECTION(POINT(20),POLYGON((00,10,11,01,00)))');



MARCODIFELICE

Geometry/geographysubtypes

POLYHEDRALSURFACETIN(triangularirregularnetworks)

CIRCULARSTRINGSCOMPOUNDCURVESCURVEPOLYGONS



MARCODIFELICE

SRID(SpatialReferenceIdentifier)² Spatialreferencesystemcurrentlyemployed

Ø  Geoidandprojectionmodelinuse²  Itcanbeomittedforgeometrytypedata²  Itmustbeprovidedforgeographicaltypedata² Numericidàprimarykeyvalueofthetable

spatial_ref_sys

psridGEOMETRY(POINT,4269)



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²  ConstructorfunctionsallowcreatingnewPOSTGISspatialobjects.²  Buildnewobjectsfromrawdataininput²  Startfromexistingdataandapplysome

transformation(e.g.decompose,slice,splice,dice).Ø  ST_GeomFromTextàBuildgeometriesfromwellknowtextØ  ST_GeomFromWKBàBuildgeometriesfromabinaryrepresentationØ  ST_GeomFromGeoJSONàBuildgeometriesfromaGEOJSONformatØ  ST_GeomFromKMLàBuildgeometriesfromaKMLformat



MARCODIFELICE

²  ConstructorfunctionsallowcreatingnewPOSTGISspatialobjects.²  Buildnewobjectsfromrawdataininput²  Startfromexistingdataandapplysome

transformation(e.g.decompose,slice,splice,dice).

[1]Examplefrom:https://live.osgeo.org/archive/11.0/it/quickstart/postgis_quickstart.html

CREATETABLEcities(idint4primarykey,namevarchar(50),the_geomgeometry(POINT,4326));

INSERTINTOcities(id,the_geom,name)VALUES(1,ST_GeomFromText('POINT(-0.125751.508)',4326),'London,England');INSERTINTOcities(id,the_geom,name)VALUES(2,ST_GeomFromText('POINT(-81.23342.983)',4326),'London,Ontario');INSERTINTOcities(id,the_geom,name)VALUES(3,ST_GeomFromText('POINT(27.91162491-33.01529)',4326),'EastLondon,SA');



MARCODIFELICE

²  ConstructorfunctionsallowcreatingnewPOSTGISspatialobjects


SELECT*FROMcities;id|name|the_geom----+-----------------+----------------------------------------------------1|London,England|0101000020E6100000BBB88D06F016C0BF1B2FDD2406C149402|London,Ontario|0101000020E6100000F4FDD478E94E54C0E7FBA9F1D27D45403|EastLondon,SA|0101000020E610000040AB064060E93B4059FAD005F58140C0(3rows)

BinarySpatialDatarepresentation



MARCODIFELICE

²  ConstructorfunctionsallowcreatingnewPOSTGISspatialobjects


SELECTid,ST_AsText(the_geom),ST_AsEwkt(the_geom),ST_X(the_geom),ST_Y(the_geom)FROMcities;id|st_astext|st_asewkt|st_x|st_y----+------------------------------+----------------------------------------+-------------+-----------1|POINT(-0.125751.508)|SRID=4326;POINT(-0.125751.508)|-0.1257|51.5082|POINT(-81.23342.983)|SRID=4326;POINT(-81.23342.983)|-81.233|42.9833|POINT(27.91162491-33.01529)|SRID=4326;POINT(27.91162491-33.01529)|27.91162491|-33.01529(3rows)



MARCODIFELICE




MARCODIFELICE

POSTGISdistance-basedoperators

floatST_Distance(geometryg1,geometryg2);floatST_Distance(geographygg1,geographygg2);floatST_Distance_Sphere(geographygg1,geographygg2);floatST_Distance_Spheroid(geographygg1,geographygg2);

SELECTp1.name,p2.name,ST_Distance_Sphere(p1.the_geom,p2.the_geom)FROMcitiesASp1,citiesASp2WHEREp1.id>p2.id;name|name|st_distance_sphere-----------------+-----------------+--------------------London,Ontario|London,England|5875766.85191657EastLondon,SA|London,England|9789646.96784908EastLondon,SA|London,Ontario|13892160.9525778(3rows)



MARCODIFELICE

POSTGISarea-basedoperators

floatST_Area(geometryg1);

SELECTST_AREA(R1.GEOM)/1000000,R1.DEN_REGFROMREGIONISCHEMA.REGIONIASR125393.8763609287|"Piemonte”3258.90668928528|"Valled'Aosta”23862.4108382986|"Lombardia"



MARCODIFELICE

POSTGISbounding-boxoperators

Smallestrectangularboxwithedgesparalleltotheaxesofthecoordinateplanethatiscompletelyenclosingageometryobject.

²  Arectangularboxiscompletelyspecifiedbythecoordinatesofthetwooppositecorners.



MARCODIFELICE




MARCODIFELICE


Codefromhttps://postgis.net/docs/geometry_overlaps.html

SELECTtbl1.column1,tbl2.column1,tbl1.column2&&tbl2.column2ASoverlapsFROM(VALUES

(1,'LINESTRING(00,33)'::geometry),(2,'LINESTRING(01,05)'::geometry))AStbl1,

(VALUES(3,'LINESTRING(12,46)'::geometry))AStbl2;

column1|column1|overlaps---------+---------+----------

1|3|t2|3|f

(2rows)



MARCODIFELICE

POSTGISgeometryrelationshipsoperators

booleanST_Intersects(geometrygeomA,geometrygeomB);booleanST_Intersects(geographygeogA,geographygeogB);geometryST_Intersection(geometrygeomA,geometrygeomB);geographyST_Intersection(geographygeogA,geographygeogB);booleanST_Within(geometryA,geometryB);booleanST_Contains(geometryA,geometryB);booleanST_Overlaps(geometryA,geometryB);booleanST_Touches(geometryg1,geometryg2);booleanST_Equals(geometryA,geometryB);



MARCODIFELICE

POSTGISgeometryrelationshipsoperators

SELECTST_Intersects('POINT(00)'::geometry,'LINESTRING(20,02)'::geometry);st_intersects---------------f(1row)SELECTST_Intersects('POINT(00)'::geometry,'LINESTRING(00,02)'::geometry);st_intersects---------------t(1row)

Codefromhttps://postgis.net/docs/ST_Intersects.html



MARCODIFELICE




MARCODIFELICE

²  POSTGISisabletoimportreal-worlddatathroughcommand-linetools(built-ininPOSTGISorfromexternalpackages).

Osm2pgsqlàcommand-linebasedprogramconvertingOpenStreetMapdatatoapostGIS-enabledPostgreSQLdatabase.

osm2pgsql--usernamepostgres--databasegis--port5432--hstorename.osm

² Key-valuestorewithinPostgres² Eachcolumnhasacolumnnamedtagsusingthehstoreengine

https://wiki.openstreetmap.org/wiki/Osm2pgsql



MARCODIFELICE

²  POSTGISisabletoimportreal-worlddatathroughcommand-linetools(built-ininPOSTGISorfromexternalpackages).

Osm2pgsqlàcommand-linebasedprogramconvertingOpenStreetMapdatatoapostGIS-enabledPostgreSQLdatabase.

selectcount(*)FROMplanet_osm_pointwhere((tags->'man_made')='tower');count-------447




MARCODIFELICE

²  POSTGISisabletooutputgeometriesandgeographiesinseveralstandardformats.


textST_AsKML(geometrygeom,integermaxdecimaldigits=15);textST_AsKML(geographygeog,integermaxdecimaldigits=15);textST_AsGeoJSON(geometrygeom,integermaxdecimaldigits=15,integeroptions=0);textST_AsGeoJSON(geographygeog,integermaxdecimaldigits=15,integeroptions=0);

textST_AsKML(geometrygeom,integermaxdecimaldigits=15);textST_AsKML(geographygeog,integermaxdecimaldigits=15);textST_AsGeoJSON(geometrygeom,integermaxdecimaldigits=15,integeroptions=0);textST_AsGeoJSON(geographygeog,integermaxdecimaldigits=15,integeroptions=0);

SELECTST_AsGeoJSON('LINESTRING(123,456)');st_asgeojson----------------------------------------------------------------------------------{"type":"LineString","coordinates":[[1,2,3],[4,5,6]]}



MARCODIFELICE




MARCODIFELICE

²  POSTGIScanbecoupledwithexternaltoolsallowinguserstoviewandanalyzespatialdatacontainedintheDB(e.g.outputofqueries).² QGIS² ArcGIS² OpenJUMP² Udig² GVSIG



MARCODIFELICE

²  QGIS(https://www.qgis.org/it/site/)FreeandOpen-sourceGeographicInformationSystems



MARCODIFELICE




MARCODIFELICE

²  Indexingspeedsupsearchingbyorganizingthedataintoasearchtreewhichcanbequickly.

² Withoutindexing,anysearchforafeaturewouldrequirea“sequentialscan”ofeveryrecordinthedatabase.

https://webdocs.cs.ualberta.ca/~holte/T26/b-trees.html

B-treeinRelationalDatabases

CREATEINDEXindex_nameONtable_name(column1_name,

column2_name);



MARCODIFELICE

R-treedatastructure

² Objectsarerepresentedthroughtheirminimumboundingrectangle.

² Aparentnodefullycontainstheboundingboxesofitschildnodes.

² Leafnodesdescribeasingleobject.

ENHANCEDSEARCHOPERATIONS²  InputàSearchrectangle²  Usetheboundingboxestodecidewhetheror

nottosearchinsideasubtree.


location-aware computing · 2019. 10. 17. · spatial database: modeling and implementation with...

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