Search with Polygons Another Approach to Solr Geospatial Search

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1、SearchwithPolygonsAnotherApproachtoSolrGeospatialSearchDr.AndrewL.UrquhartMay10,2012Copyright©2012RaytheonCompany.Allrightsreserved.CustomerSuccessIsOurMissionisaregisteredtrademarkofRaytheonCompany.Whatisthe“BurningPlatform”?Needtobreakdependencyonexpen

2、sivelicensesforproprietarydatabase–Majorcostdriver–UnsustainableincurrenteconomicenvironmentSolridentifiedaspromisingreplacementcandidate–Excellentcost–Excellentperformance–Excellentaccesstosourcecode–MajorweaknessinrequiredGeospatialSearchcapability–IsG

3、eospatialSearchweaknessmitigationpossible?MustindexpointsforsearchbypolygonsShouldindexpolygonsforsearchbypolygonsSolrpromising,PolygonGeospatialSearchneeded5/16/122WhatHasBeenProduced?Asingleadd-inJARfileplusSchemaenhancements–OldervariantrequiresaGPL

4、libraryforpoint-in-polygonsupport–NewervariantrequiresnoexternallibrariesInternalsuseinherentthree-dimensionalmathematics–LUCENE-3795/“LuceneSpatialPlayground”geospatialsearchcapabilityusesJTSlibraryforpolygonsupport–JTSusestwo-dimensionalmathematics–JTS

5、hasgreatervulnerabilitytospecialpointsNorthandSouthPoles180°meridianPotentialproblemforcustomerapplications–JTSsupportscomplexpolygonsAlternativeapproachonlysupportssimplepolygonsatthistimeSingleJARfileusing3-Dinternalmathematics5/16/123WhatistheMagic

6、?Variantgeohashcoding–64-bitlongintegersinsteadofstrings–ThreemostsignificantbitsforoctantsofEarth’ssurfaceDividingatequator,primemeridian,90°E/Wmeridians,180°meridian–Followedbythree-bitgroupsOnestop/continuebitOnenorth/southsplitbitOneeast/westspli

7、tbit–Allowsprecisiondownto10cm×10cmsquaresatequator–Producesvarious-size“tiles”representingpartsofEarth’ssurfacePointsindexedbythesmallesttilewhichcontainsthepointE/WN/SE/WC/SN/SE/WC/SN/SE/WC/SN/SE/WC/SN/SE/WIndexingusing64-bitintegersfortrie-drivensearc

8、h5/16/124WhatAboutPolygons?Polygonsindexedascollectionoftilesinsidepolygon–Largertilescompletelycontainedinindexedpolygonarenotsubdivided–SmallestindexedtilesmayextendoutsideindexedpolygonPolygonsindexedwithserieso