[postgis-users] How efficient are spatial indexes?

[Adam Wells]

Hi All,

I am in the process of writing an application that involves keeping track of a large number of calendar appointments - things that have start and end dates.  It is important to make sure that appointments for a given person do not overlap, which will involve lots of date comparisons in db queries.

Now I might be smoking crack, but I had the following idea, and would value feedback:

I could represent an appointment as a line in a geometry column - the X axis would be time (as integer values), and the Y axis would be the ID of the user.

user id      222
start time 1348095600000 (09/20/2012 09:00:00)
end time 1348099200000 (09/20/2012 10:00:00) 

The WKT for the geometry would be LINESTRING(1348095600000 222, 1348099200000 222)

If all appointments had such geometries stored, then I could use spatial queries to find all appointments within a given range by looking for ST_Overlaps etc.

Is the spatial index efficient at this sort of thing?  More so than doing date range checking in a traditional index?

Is this a fundamentally lame approach, or it it worth going to the trouble of benchmarking?

Cheers,

Adam