A spatial data infrastructure (SDI) is a data infrastructure implementing a framework of geographic data, metadata, users and tools that are interactively connected in order to use spatial data in an efficient and flexible way.

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11
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3answers
986 views

Can spatial index help a “range - order by - limit” query

Asking this question, specifically for Postgres, as it has good supoort for R-tree/spatial indexes. We have the following table with a tree structure (Nested Set model) of words and their ...
6
votes
2answers
354 views

Less restrictive query return less result due to simple removing one additional constraint

Look at this query SELECT DISTINCT TB.ID, TB.Latitude, TB.Longitude, 111151.29341326*SQRT(pow(-6.185-TB.Latitude,2)+pow(106.773-TB.Longitude,2)*0.98839228980165) AS Distance FROM ...
8
votes
2answers
1k views

How do Application Like Yelp Retrieve distance information from data base efficiently

For example, say I have a table: Business(BusinessID, Lattitude, Longitude) All are indexed of course. Also there are 1 million records Say I want to find businesses closest to 106,5, for example, ...
3
votes
3answers
721 views

How do I design a database for continents, countries, regions, cities and POIs?

I am not a database designer so I'm having trouble designing database with GIS information. The goal is to create a system with continents, countries, regions (including states, sub-regions, ...
3
votes
1answer
114 views

Good layout of 3d point data for spatial queries in Postgres?

Like shown in another question, I deal with a lot (>10,000,000) entries of points in a 3D space. These points are defined like this: CREATE TYPE float3d AS ( x real, y real, z real); If I am ...
0
votes
1answer
192 views

MySQL Syntax - Searching points within polygons using GeomFromText

I am trying to select points within polygons using the GIS/spatial extensions for MySQL. I'm fairly new to this, so bear with me if this is an elementary question. I have points defined as text ...
0
votes
2answers
620 views

migrate SQL Server geography data to PostGIS geometry data

I'm trying to use SSIS to transfer point data from a Geography column in SQL Server 2008 R2 to a geometry column in a Greenplum (Postgres 8.2.15) database with PostGIS. I know there's a way to do the ...