Re: How to reject overlapping timespans?

Andreas <maps.on@gmx.net> hat am 17. Februar 2013 um 18:02 geschrieben:
> Hi,
>
> I need to store data that has a valid timespan with start and enddate.
>
> objects ( id, name, ... )
> object_data ( object_id referencs objects(id), startdate, enddate, ... )
>
> nothing special, yet
>
> How can I have PG reject a data record where the new start- or enddate
> lies between the start- or enddate of another record regarding the same
> object_id?

With 9.2 you can use DATERANGE and exclusion constraints

test=# create table maps(id int, duration daterange, exclude using gist(id with
=, duration with &&));
NOTICE:  CREATE TABLE / EXCLUDE will create implicit index
"maps_id_duration_excl" for table "maps"
CREATE TABLE
test=*# insert into maps values (1,'(2013-01-01,2013-01-10]');
INSERT 0 1
test=*# insert into maps values (1,'(2013-01-05,2013-01-15]');
ERROR:  conflicting key value violates exclusion constraint
"maps_id_duration_excl"
DETAIL:  Key (id, duration)=(1, [2013-01-06,2013-01-16)) conflicts with existing
key (id, duration)=(1, [2013-01-02,2013-01-11)).
test=*#


Regards, Andreas