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173 lines
4.9 KiB
XML
173 lines
4.9 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<presentation css="10gen-strict.css">
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<topic>MongoDB</topic>
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<title>Geoqueries with MongoDB</title>
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<event>MongoDB Belgium meetup</event>
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<location>Ghent, Belgium</location>
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<lat>51.037235</lat><lon>3.736634</lon>
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<date>March 16th, 2015</date>
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<speaker>Derick Rethans</speaker>
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<email>derick@mongodb.com</email>
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<twitter>derickr</twitter>
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<joindin>http://derickrethans.nl/talks/mongogeo-belgium-mug</joindin>
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<slide>slides/mongodb/title.xml</slide>
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<slide>slides/mongodb/closed-pub.xml</slide>
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<!-- A few words about our dataset -->
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<slide>slides/mongodb/few-words-about-osm.xml</slide>
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<slide>slides/mongodb/flat-vs-sphere.xml</slide>
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<slide>slides/map/flat-sphere-flickr.xml</slide>
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<!-- DATA STORAGE -->
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<!--
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No more [ lon, lat ], but geojson instead
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SAY WHERE ELSE GeoJson is used
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-->
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<slide>slides/mongodb/geojson.xml</slide>
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<!--
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POINT:
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show an image, and the GeoJson under
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-->
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<slide>slides/mongodb/geojson-point.xml</slide>
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<!--
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LINESTRING:
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show an image, and the GeoJson under
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-->
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<slide>slides/mongodb/geojson-linestring.xml</slide>
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<!--
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POLYGON:
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show an image, and the GeoJson under
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-->
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<slide>slides/mongodb/geojson-polygon.xml</slide>
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<!--
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CELLS,
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We divide the surface of the earth into cells
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A library called S2 from Google does the hard work
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Cells have a level which define the size of the cell.
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S2 provides 31 levels
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The higher the level, the smaller the cell, and therefore the more needed to cover the earth
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By default, we use all levels between 500m on a side and 100km on a side
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-->
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<slide>slides/mongodb/cells.xml</slide>
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<!--
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Show grid of (part of) London:
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- Point, Westminster palace
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- Line, Oxford Street
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- Polygon, Hyde Park
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-->
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<slide>slides/mongodb/cells-level10-example-london-1.xml</slide>
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<slide>slides/mongodb/cells-level10-example-london-2.xml</slide>
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<slide>slides/mongodb/cells-level10-example-london-3.xml</slide>
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<!-- operators
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$near
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find stuff near a point
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index required
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$geoWithin
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find stuff within a polygon/circle
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index NOT required
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$geoIntersects
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find stuff that intersects with other stuff
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index NOT required
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-->
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<slide>slides/mongodb/geo-in-2.4.xml</slide>
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<!-- near
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- Example with road and park
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- slide with index/no index, and comparsion with 2.2?
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-->
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<!-- geoWithin
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- Example with road and park
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- slide with index/no index, and comparsion with 2.2?
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-->
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<!-- geoIntersects
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- Example with road and park
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- slide with index/no index, and comparsion with 2.2?
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-->
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<slide>slides/mongodb/geo-near.xml</slide>
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<!--
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NEAR
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Starts from a point
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Looks at concentric donuts from that point
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Want to look at documents within the donut
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If distance from query point to document is within the donut, output
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Adapts size of the donut as needed
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-->
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<slide>slides/mongodb/geo-near-explanation-0.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-1.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-2.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-3.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-4.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-5.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-6.xml</slide>
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<slide>slides/mongodb/geo-near-explanation-7.xml</slide>
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<!--
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GeoWithin/GeoIntersecs
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Generate a covering for geometry in query
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Look at all points in all overlapping cells
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Cells may be larger or smaller than our covering
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Must look at cells that contain our covering
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Must look at cells that we contain
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See if documents are within or intersect our query geometry
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Show examples of:
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- within: The Palace of Westminster (point) in "City of Westminster" (polygon)
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- intersect: thames (line) crossing London (polygon)
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-->
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<slide>slides/mongodb/geo-within.xml</slide>
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<slide>slides/mongodb/geo-within-1.xml</slide>
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<slide>slides/mongodb/geo-within-2.xml</slide>
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<slide>slides/mongodb/geo-intersects.xml</slide>
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<!--
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Without index:
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$near
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Look at every point
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Sort by distance
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Very slow, so requires an index.
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$geoWithin
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Look at every document
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Is it within the query polygon?
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Order is arbitrary
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$geoIntersects
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Look at every document
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Does it intersect with the query geometry?
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Order is arbitrary
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-->
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<!-- AGGREGATION:
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- show tube stations per borough
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- show pubs by borough
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http://docs.mongodb.org/manual/reference/aggregation/#stage._S_geoNear
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- distance is important
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- $geoNear in aggregation can't deal with more than one 2dsphere index
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- spherical option is *required* when using a 2dsphere index
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-->
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<slide>slides/mongodb/geo-aggregation.xml</slide>
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<slide>slides/mongodb/geo-aggregation2.xml</slide>
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<slide>slides/mongodb/big-polygon1.xml</slide>
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<slide>slides/map/osm-xapi.xml</slide>
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<slide>slides/map/import-script-manchester.xml</slide>
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<slide>slides/mongodb/resources.xml</slide>
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</presentation>
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