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Re: Spatio-Temporal Functions

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Nick Raj <nickrajjain(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Spatio-Temporal Functions
Date: 2011-02-28 21:35:59
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Lists: pgsql-hackers
On Sat, Feb 26, 2011 at 1:43 PM, Nick Raj <nickrajjain(at)gmail(dot)com> wrote:
> Hi,
> I am writing some spatio-temporal function in postgis.
> Like, ST_Enters( obj_geom, boundary_geom, time t1,time t2)
> For example- Does vehicle enters in ABC between time t1 to t2?
> Let us suppose, i take only one object geometry at a time and do compare
> then i could not produce the output because it is continous function of time
> i.e. Enters is made up of Disjoint -> Touches -> Inside .
> So, for creating this function, i require all the object's geometry before
> it go inside the function. So that it can call only once.
> My first problem is that
> create or replace function ST_Enters(????, geometry,timestamp,timestamp)
> returns boolean ............
> Which kind of data type to be used because i have to catch more than 1000
> rows and geometry[] doesn't work for it.
> So, Can anyone tell me which data type can be used to catch this?
> Second,
> How can i use this function in SQL? Because suppose i write query like
> select ST_Enters ( obj_geom, (select boundary_geom from boundary),
> '25/2/2011 12:23:32','26/2/2011') from vehicledata where vehicleid= 'XYZ';
> and again it comes out to be one object geometry matches with boundary
> geometry,
> if i store the inbetween data in some temp table then it creates a lot of
> computation between the table and if it end up in between then table may
> contains some wrong data.
> So, How to use this function in SQL in continuous manner??
> Thanks in advance.

I think you might need to ask these questions on the PostGIS lists...

Robert Haas
The Enterprise PostgreSQL Company

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