Optimisation is the act of making things as good as possible with regard to some criterion, eg. more efficient, faster or slimmer.
7
votes
3answers
1k views
how to find 20 closest points efficiently
Say I want to find 20 closest business near me.
My table structure is like this:
BusinessID varchar(250) utf8_unicode_ci No None Browse distinct values Change Drop ...
13
votes
2answers
3k views
Looking for fastest solution for Point in Polygon analysis of 200 million points
Apologies for asking a question that has been asked before -- I've read through answers, and I'm left wondering how to implement the recommendations. I've never used SQL, Python, C, and have only ...
3
votes
1answer
178 views
How can I more efficiently select related records?
Below is the code I'm using to replicate the "related tables" button in ArcMap. In ArcMap that button selects features in one feature class or table based on the selection of features in another ...
6
votes
5answers
849 views
Effectively displaying a large amount of data on Google Maps APi
I have about 20 layers that I'd like to put on a Google maps API. I assume I'll need some form of a tile cache server and perhaps under mapserver or geoserver. These layers amount to about 400mb so ...
4
votes
3answers
340 views
How to efficiently find points within an elliptical area?
Using PostGIS 2.0.0 I need to filter the results of a function, which returns many POINTs, to find the ones that lie within an elliptical area defined by two points and a distance (all parameters ...
14
votes
5answers
2k views
Ways to Speed Up Python Scripts Running As ArcGIS Tools
This is a pretty general question. I just wondering what tips and tricks GIS programmers have used to speed up arcpy scripts that you import into the toolbox and run.
I work most everyday writing ...
8
votes
4answers
671 views
Fastest spatial storage format?
I am wondering what storage method will result in the fastest reading of the map vectors for rendering. SHP? PostGres? SQLite? (They do not change often and I do not need spatial functions for these ...
5
votes
3answers
2k views
ST_Intersection slow query
I am trying to perform an intersection between two layers:
Polyline layer representing some roads (~5500 rows)
Polygon layer representing irregularly shaped buffers around various points of interest ...
10
votes
1answer
228 views
Are there any intelligent travelling salesmen?
Jokes aside, I have had a routing problem that is almost a travelling salesman problem (TSP):
the starting point is defined
the end point coincides with the starting point
each node has to be ...
6
votes
1answer
737 views
Performance Gain Through GIST Index for Point in Polygon Query
I have two tables: locations(id,region_id,the_geom) and regions(id,the_geom). For each location point I want to determine the region it is located in:
UPDATE locations SET region_id =
(SELECT id ...
3
votes
1answer
150 views
geodjango slowness and debugging
I'm using geodjango + postgres to display polygons from tigerline on a map. Pretty simple stuff so far.
My issue is that when I use the GPolygon object: django.contrib.gis.maps.google.GPolygon there ...
3
votes
3answers
2k views
How to fix performance problem in PostGIS ST_Intersects?
I'm a newbie in postgis and I have a problem in query performance.
This my query:
SELECT DISTINCT ON (userid) userid ,ST_AsText(position), timestamp
FROM table1
WHERE ST_Intersects ( ...
