[postgis-users] Extent on multiple tables

[strk at refractions.net]

On Fri, Oct 21, 2005 at 11:42:52AM +0100, Mark Cave-Ayland wrote:
> Hi Lars/strk,
> 
> > -----Original Message-----
> > From: postgis-users-bounces at postgis.refractions.net 
> > [mailto:postgis-users-bounces at postgis.refractions.net] On 
> > Behalf Of strk at refractions.net
> > Sent: 21 October 2005 11:22
> > To: postgis-users at postgis.refractions.net
> > Subject: Re: [postgis-users] Extent on multiple tables
> > 
> > 
> > You might try:
> > 
> > 	select extent(g) from (
> > 		select the_geom from table1
> > 		union all
> > 		select the_geom from table2
> > 	) as foo;
> 
> Isn't there an extent() missing from each of the individual tables?
> Otherwise you have to load all the geometries from all the tables into
> memory before you calculate the overall extent, rather than working on a per
> table basis.

Are you sure inspected geometries will be kept in memory after
state function feed ?

--strk;