geospatial,postgis,postgresql-9.3,spatial-query,spatial-index

There is no Postgis type for representing a circle with 100% accuracy, ie, with a centre point and a radius, as there is with SQL Server's circular arcs. As pointed out in the comments, you can approximate a circle with the 2nd form of ST_Buffer, ie, ST_Buffer(point, distance, num_seg_quarter_circle). As...

c++,data-structures,spatial-index,octree

ALT1 is correct. Given that you want to limit the maximum number of objects (triangles) in a node, you will need to subdivide nodes that will contain many triangles. This inevitably leads to having a single triangle in multiple nodes, unless you want to subdivide triangles so that they fit...

sql,optimization,indexing,spatial,spatial-index

As ever with Spatial Indexing, you end up finding that testing a variety of grid settings on your data set can yield different results to those of others. That said, I find setting Low at all levels, or Medium, Low, Low, Low yields great results with Points due their simplistic...

c++,group,frequency,spatial-index,r-tree

R-trees are one of the most useful spatial indexing data structures yet are proven useful for specific domains and problems. That been said, that's not a reason to refrain from being didactic (after all what's asked may be a simplification of the actual problem). If you choose to use R-trees...

sql-server,geospatial,spatial-index

You only need one of the indices for the Position field in each table. Having 2 is redundant and will harm performance from the standpoint that any database writes to those fields would have to update both. You do require having the index in both tables, since you are looking...

mongodb,spatial-index,2dsphere

Try to change o comment this part: query: { category: "public" } Because in the elements there is no "category" field...

You could create two additional data-sets, "projecting" points into each axis by removing the other coordinate. Then, you'll have transformed the problem into a 1-dimensional nearest-neighbour search.

mysql,distance,spatial-query,spatial-index

It doesn't help that Spot is indexed, MySQL still have to calculate each st_distance from the point 10.0, 12.0 to be able to order it. If you wan't to do searches like this fast you should add a where condition to narrow the number of points that can might close...