Re: Dilemma: is gid really useful in a geoDB?

> Antonello wrote:
>> Hi list,
>>
>> I have a dilemma: is gid really useful in a geoDB?
>> I am building a geodb for several harbor. When I create a layer(table
>> with geometry) in postgis, I need a gid like a primary key, or I can
>> use a different one? Can I  use several field of from the table like a
>> primary key?
>>
>> I am not new in the gis, but why in almost all geoDB I saw there is a
>> gid?! Is it really necessary? Do it come from shapefile standards?
>>
>> For example QuantumGIS doesn't work if the layer has only one primary
>> key, there are other application that don't work like qGis?
>>
>
> Hello Antonello,
>
> There is basically a requirement to have some kind of unique way of
> accessing any given record. This is so programs can update the record or
> fetch the records later based on a unique id. Also some systems might
> expect that the uid be an integer. So adding the gid column is a
> convenience.
>
> If you know your usage patterns and you know the requirements for the
> software you are using with the database, then you can probably safely
> remove or change it to something else. I don't think gid needs to be the
> primary key if you have something else, you could just make the gid a
> unique column.
>
> -Steve
> _______________________________________________
> postgis-users mailing list
> postgis-users@...
> http://postgis.refractions.net/mailman/listinfo/postgis-users