1 / 28

A Spatio-Temporal Query Language for a data model based on XML.

A Spatio-Temporal Query Language for a data model based on XML. J. E. Córcoles, J. García-Consuegra, J. Peralta and E. Navarro. Index. Introduction STQ Syntax Query Processing Query Decomposition Operator Execution Example of Query Processing Conclusions Future Work. Index.

aldon
Download Presentation

A Spatio-Temporal Query Language for a data model based on XML.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Spatio-Temporal Query Language for a data model based on XML. J. E. Córcoles, J. García-Consuegra, J. Peralta and E. Navarro

  2. Index • Introduction • STQ Syntax • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  3. Index • Introduction • STQ Syntax • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  4. Introduction (I) • XML (eXchanged Markup Language) • XML => The solution to the problem of these heterogeneous systems • XML => Exchange language of geographic information • OpenGIS => GML (Geography Markup Language)

  5. Introduction (II) • STQ (Spatio-Temporal Query language) over GML. • Select-from-where syntax • Spatial operators (overlap, cross, etc) • Temporal operators (after, before, etc). • Traditional operators (=,>, <,...) for non-spatial information

  6. Index • Introduction • Syntax of STQ • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  7. Syntax of STQ (I) • Clean Semantics • Path Expressions • Ability to return an XML document • Ability to query and return XML tags and attributes • Intelligence type coercion • Handles unexpected data • Ability to allow queries when the DTD is not fully known • Returns unnamed attributes • Preserves Order • Allows Spatial and Temporal operators

  8. Syntax of STQ (I) 1. Clean Semantics Select C.modelMember.Parcel.cadastreId From [http://www.uclm.es//prove.xml].CityModel as C Where C.name Like ‘Albacete’ 2. Path Expressions C.modelMember.Parcel

  9. Syntax of STQ (II) 3. Ability to return an XML document Select C. ModelMemeber.Parcel.extendOf From [http://www.uclm.es//prove.xml].CityModel as C Where C.name Like ‘Albacete’ and Parcel.number = 103 The XML document return for the query is: <Polygon> <outerBoundaryIs> <LinearRing> <coordinates> 0.0,0.0 40.0,0.0 40.0,10.0 0.0,10.0 </coordinates> </LinearRing> </outerBoundaryIs> </Polygon>

  10. Syntax of STQ (III) • 4. Ability to query and return XML tags and attributes • Select M.Parcel.extendOf • From [http://www.uclm.es//probe.xml].CityMode.modelMember as M • Where M.(street%) Like ‘Capitan Grant’ • 5. Intelligence type coercion (String-Integer).

  11. Syntax of STQ (IV) 6. Handles unexpected data 7. Ability to allow queries when the DTD is not fully known Select C From [http://www.uclm.es//prove.xml].CityModel as C Where C.(name | description) Like ‘Albacete’

  12. Syntax of STQ (V) 8. Returns unnamed attributes Select C.(^ modelDate, ^modelMember) From [http://www.uclm.es//prove.xml].CityModel as C 9. Preserves Order. • In the current version of STQ data order is not preserved

  13. Syntax of STQ (VI) 10. Allows Spatial and Temporal operators • Spatial Operators: • Disjoint, Meet, Equal, Overlap, Contains, Inside), Covers and covered_by. • Within, Near, Crossing, Along, Finish • Length, Surface, Perimeter and Buffering. • Temporal Operators: • Date Is, After and Before

  14. Syntax of STQ (VII) • Other features of STQ is the possibility to use several XML documents in the same query. select_statement ::= . . FROM table_commalist: f1 table_commalist ::= addresshttp: d1 PERIOD table:s1 AS NAME:a1

  15. Index • Introduction • Syntax of STQ • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  16. Query Processing (I) • The query process for a STQ query has two well-defined phases: • Query decomposition to transform the STQ query into an Operator Tree. • To run the Algebra relational operators. • Execution of alphanumeric operators (XQL) • Execution of spatial operators (R-tree)

  17. Query Processing (II)Query Decomposition • Query decomposition to transform the STQ query in an Operator Tree has four sub-phases: • Normalization (conjunctive normal) • Analysis (query graph or connection graph) • Redundancy elimination • Rewriting (operator tree)

  18. Query Processing (III)Operator Execution • After decomposition, a query may have two kinds of operators in the Select (Algebra relational) operator. • Alphanumeric operators (>,<,like): SQT is based on XQL to execute alphanumeric operators • Spatial operators STQ creates a R-tree spatial structure to execute spatial operators. • Temporal operators: SQT is based on XQL to execute temporal operators of higher level.

  19. Index • Introduction • Syntax of STQ • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  20. Example of Query Processing (I) • Example : • To obtain all Parcel Identifiers (<modelMember><cadastreId>) that have a number (<modelMember><number>) greater than 100, and whose surface is contained in the zone with name ‘Carretas’.

  21. Example of Query Processing (II) • The SQT query that represents the last query may be: Select P.Cadastreid From [http://www.uclm.es//prove.xml].CityModel.modelMember.Parcel as P, [http://www.uclm.es//prove.xml].CityModel.modelMember.District as D Where P.number > 100 and D.name like ‘Carretas’ and P.extendOf.Contain.(D.extendOf)

  22. Example of Query Processing (III) • After the decomposition process, this query generates the following operator tree shown below.

  23. Example of Query Processing (IV) • The result set is a XML document with the totality of elements that have carried out all the conditions. For example: <cadastreId> 3050 </cadastreId> <cadastreId> 3008 </cadastreId>

  24. Index • Introduction • Syntax of STQ • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  25. Conclusions • STQ: Spatial and temporal query language over XML. • Spatio-Temporal feature is not included in the most widely-known XML query languages • STQ is applied over a GML data model.

  26. Index • Introduction • Syntax of STQ • Query Processing • Query Decomposition • Operator Execution • Example of Query Processing • Conclusions • Future Work

  27. Future Work • Features such as Preserver order and Intelligence type coercion will be included • Implementation of Dataguides: • Single user interface. • queries on the Web.

  28. E-mail • Questions and comments can be sent to the following e-mail address: • corcoles@idr-ab.uclm.es

More Related