[postgis-users] Re: [postgis-users] Re: [postgis-users] Postgis too slow

[Paul Ramsey]

You use ordinary PHP and SQL to find the extents, then set the extents
and render using PHP/Mapscript. Abstractly, it will look like this:

pg_exec("select extent(the_geom) as the_extent from the geoteable where
<where clause>")
$map->extent = <the_extent>;
$map->draw;

See?

"shpr at libero.it" wrote:
> 
> ok, what I just say is not possible, but then how can I do this with
> PHP Mapscript? What is the equivalent of itemquery in PHP mapscript? I
> doesn't find it?
> In other words, how can I find an object and calculate its extension
> under PHP mapscript?
> I thinks that is one of the main functionality that a GIS should have,
> but I didn't find any PHP Mapscript applications that have it. Moreover
> I didn't find applications under mapserver that resolve this problem.
> 
> Any idea?
> Is there a way with ASP or JAVAServlet tecnologies?
> 
> Thanks
> Stefano.
> 
> > ok, I don't still try if this is the problem, but I think so.
> >
> > If I develop, for example, a java servlet that extract the oid (is
> > possible? I think so) and then I create a filter query only on this
> > attribute, do you think that this can work faster?
> >
> > Stefano.
> >
> >
> > > OK, I am now pretty sure the problem was (2) in my previous email. Y
> ou
> > r
> > > mapfile layer definition is below. What you are doing is emulating a
> n
> > > item query by using the FILTER parameter. This is *bad*. It will *no
> t*
> > > work, because the spatial parameter is way too big, and your attribu
> te
> > > indexes will never ever get used. The pgsql query optimizer just doe
> s
> > > not know how to handle this combination of spatial and attribute
> > > indexes.
> > >
> > > To verify that this is the problem, either (1) change your EXTENT so
> > > that it is a very *small* box which contains just your one test road
>  a
> > nd
> > > very little else. Now see how fast it runs. Or (2) remove the FILTER
> > > entirely (don't to 1=2, *remove* it) and zoom into a small area. Now
>  p
> > an
> > > around the dataset. That should demonstrate the native spatial query
> > > speed.
> > >
> > > You are not going to be able to do this query with the standard CGI
> > > interface. You are going to have to use PHP MapScript and use PHP di
> re
> > ct
> > > connection to pgsql to do the attribute query and find the extent of
>  t
> > he
> > > resultant lines, then set the extent of your map appropriately, then
> > > render. If you have simple queries, you can use the itemquery in the
>  C
> > GI
> > > interface, but your query is too complex for that.
> > >
> > > This is map postgis layer:
> > >
> > > LAYER
> > > STATUS OFF
> > >   NAME "stradeQ"
> > > CONNECTIONTYPE postgis
> > > CONNECTION "user=postgres password=postgres dbname=market host=serve
> r
> > > port=5432"
> > >   DATA "the_geom from streets"
> > > TYPE LINE
> > > FILTER "(upper(st_nm_base) Like upper('%
> street%')) AND (l_area_id Like
> > > '%value%')
> > > AND ('%number%'='' or '%number%' between l_refaddr and l_nrefaddr or
> > > '%number%'
> > > between r_refaddr and r_nrefaddr) "
> > >
> > > CLASS
> > >   SYMBOL 0
> > >   OUTLINECOLOR 25 25 0
> > > END
> > > TEMPLATE market.html
> > > END
> > >
> > >
> > > --
> > >       __
> > >      /
> > >      | Paul Ramsey
> > >      | Refractions Research
> > >      | Email: pramsey at refractions.net
> > >      | Phone: (250) 885-0632
> > >      \_
> > >
> > > _______________________________________________
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