GEOLOCATION IN MONGODB { name: ‘Shashank Tiwari’, web: ‘shanky.org’} Wednesday, January 16, 13
Geolocation in MongoDB
Jan 15, 2015
A talk on "Geolocation in MongoDB" at the Silicon Valley MongoDB User Group. (http://www.meetup.com/MongoDB-SV-User-Group/events/91702142/)
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GEOLOCATION IN MONGODB
{ name: ‘Shashank Tiwari’, web: ‘shanky.org’}
Wednesday, January 16, 13
WHO AM I?
Entrepreneur, developer, author
Most recent book: Professional NoSQL (Wiley, 2011)
Founder : WhatNext Labs, creators of
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DEGREES OF MEASURE
Latitude
Longitude
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DEGREE OF LONGITUDE
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GEO IN MONGO
Is a world in 2D
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MONGO DOC WITH LOC
{ loc : [37.407202, -122.10716] }
{ loc : { x: 37.407202, y: -122.10716} }
{ loc : { lat: 37.407202, lon: -122.10716} }
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INDEX
db.places.ensureIndex( { loc : "2d" } )
1 geospatial index per collection
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INDEX RANGE
db.places.ensureIndex( { loc : "2d" } , { min : -500 , max : 500 } )
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INDEX PRECISION
db.places.ensureIndex( { loc : "2d" } , { bits : 26 } )
Geo-hash precision of 26bits ~ 2 feet
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EXACT QUERIES
> db.places.find({ loc : [ 37.407202, -122.10716 ]});
{ "_id" : ObjectId("50b69e66e6945f62a019f3a4"), "name" : "San Antonio Caltrain", "loc" : [ 37.407202, -122.10716 ] }
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EXPLAIN QUERY PLAN
db.places.find({ loc : [ 37.407202, -122.10716 ]}).explain();
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COMPOUND INDEX
db.places.ensureIndex( { loc : "2d", name : 1 } )
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NEAR QUERY
db.places.find({ loc : { $near : [ 37.407202, -122.10716 ]}});
Returns points sorted by distance
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WITH MAXDISTANCE
db.places.find({ loc : { $near : [ 37.407202, -122.10716 ], $maxDistance : 0.05}});
What is the unit of maxDistance? -- for latitude & longitude 1 degree ~ 69 miles
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GEONEAR QUERY
db.runCommand({ geoNear : "places", near : [37.407202, -122.10716], num : 5 });
also gives the distance
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MORE WITH GEONEAR
db.runCommand({ geoNear : "places", near : [37.407202, -122.10716], num : 5, type : “DO” });
parameters: near, num, maxDistance, query
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WITHIN A BOX
db.places.find({ loc : { $within : { $box : [[39.589821, -122.438831], [37.485200, -122.228438]] }}});
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WITHIN A CIRCLE
db.places.find({ loc : { $within : { $center : [[39.589821, -122.438831], 10] }}});
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WITHIN A POLYGON
Polygon shapes currently cannot be indexed
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SPHERICAL SUPPORT
geoNear -- spherical : true
$nearSphere
$centerSphere
Order is important, very important -- longitude, latitude
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MULTI LOCATIONS
db.places.insert({ placesVisitedToday : [ { name : "San Antonio Caltrain", loc : [37.407202, -122.10716] }, { name : "Datapipe", loc : [37.3336641, -121.8887072] } ] })
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QUERY MULTI LOC
db.places.ensureIndex( { " placesVisitedToday.loc " : "2d"} )
use uniqueDocs : true to get unique documents
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NEXT TALK
Join me to learn MongoDB in an hour!
Coming soon : Feb 1, 2013
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THANKS
More questions? web: shanky.org | twitter : @tshanky | email: [email protected]
Download and play with on Google Play and coming soon to the AppStore.
Wednesday, January 16, 13
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