php - PostgreSQL select query (GPS) -


the problem!

i have postgresql database on saving gps data of cars. i'm preparing history report , have show 2 different stutus each car according speed, firs stoped if car speed remains 0 within 5 minutes, if more 5 minutes have show parking. data gps on each 10 seconds. there way that? appreciated.

here table structure: 

create table gps_data_abl_soft (   id bigint not null default nextval('gps_data_id_seq'::regclass),   device_id bigint not null default (-1),   keyword character varying(30),   coordinate geometry,   date_time timestamp without time zone not null default now(),   message character varying(200) not null default ''::character varying,   speed real not null default 0.0,   angle real not null default 0.0,   constraint gps_data_pkey primary key (id) )

here sample data table:

i have tackled problem myself creating postgresql function! 

-- function: stop_func(bigint)  -- drop function stop_func(bigint);  create or replace function stop_func(in device_id_param bigint)   returns table(coordinate geometry, difference interval) $body$ declare     r record;     stop_records stop_record[];     speed_zero boolean;     prev_date_time timestamp;     coordinate geometry; begin      speed_zero:=false;      r in select g.coordinate, g.date_time, g.speed gps_data_abl_soft g g.device_id=device_id_param  order g.date_time     loop         if r.speed=0             if not speed_zero prev_date_time:=r.date_time; coordinate=r.coordinate; end if;              speed_zero:=true;         else              if speed_zero                  stop_records=array_append(stop_records,(coordinate, r.date_time-prev_date_time)::stop_record);             end if;              speed_zero:=false;          end if;      end loop;     return query select * unnest(stop_records);    end $body$   language plpgsql volatile   cost 100   rows 1000; alter function stop_func(bigint)   owner dr;

usage of function

 select st_asgeojson(st_transform(st_multi(st_union(coordinate)), 4326)) coordinate,    difference stop_func(device_id, start_time, end_time) group difference;

sample result here:

enter image description here


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