Reading the Same Selection from PostGIS Twice?

[Fawcett, David]

Bill, 

Take a look at the REQUIRES option in the LAYER block of your mapfile.  

http://mapserver.gis.umn.edu/docs/reference/mapfile/layer

You should be able to set it up so your non-filled polys only show up
when you display the WMS, and the filled poly layer only shows up when
the WMS layer is off.  

David.

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Bill Thoen
Sent: Wednesday, December 27, 2006 5:21 PM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Reading the Same Selection from
PostGIS Twice?


I want the layers separated because in this situation there's a WMS 
orthophoto layer that may appear above the filled polygons and below the

county outlines. Although the performance hit is negligible in this case

(apparently Linux is pretty good about caching), I just wondered if this

could be an issue at times and if there was anything I could do about
it.

Steve Lime wrote:
> If you have separate layers then you'll hit the server twice, yes. Why

> do you need them in separate layers? You certainly can achieve the 
> visual effect (outlined polygons) within a single layer definition.
>
> Steve
>
>
>   
>>>> Bill Thoen <bthoen at GISNET.COM> 12/27/2006 2:43:57 PM >>>
>>>>         
> I've got a situation where I'm pulling the same selection of US county
>
> polygons from PostGIS in two LAYERs because I want filled polygons in 
> a
>
> separate layer than the polygon outlines. I can make this work by
> defining the same DATA selection statement for each LAYER, but doesn't
>
> this hit the PostGIS server twice? Is there a way to select the 
> geometry from the database once and then split the selection into 
> separate POLYGON type and LINE type layers within the MAP object?
>
>