Mapserver and SDE, one trivial question, one informationalquestion

[Farber, Saul (ENV)]

Thanks howard, that did the trick!

The quotes around things were fudging up my results.

--saul

-----Original Message-----
From: Howard Butler [mailto:hobu at iastate.edu] 
Sent: Monday, March 14, 2005 4:07 PM
To: Farber, Saul (ENV)
Subject: Re: Mapserver and SDE, one trivial question, one
informationalquestion


Saul,

>
>I have tried many different EXPRESSION lines in the CLASS section.  
>Here are some examples: EXPRESSION "[ADMIN_TYPE] =3D 1"
>EXPRESSION "'[ADMIN_TYPE]' =3D 1"
>EXPRESSION "'[ADMIN_TYPE]' =3D '1'"
>EXPRESSION "'[ADMIN_TYPE]' eq 1"
>EXPRESSION "'[ADMIN_TYPE]' eq '1'"
>EXPRESSION "'[ADMIN_TYPE]' IN '1'"
>EXPRESSION "'[ADMIN_TYPE]' LIKE '%1%'"
>
>Etc.
>
>I've tried all the combinations of attribute name and quotes/operators 
>I can think of.  I've tried the attribute name fully qualified, 
>partially qualified and unqualified (as above).
>
>In all cases, I get a completely blank map, as though no features are 
>selected by the expression.  Any hints on what I should be putting in 
>for the expression?  Are Expressions supported in SDE layers?

Expressions are supported, and I've often had some trouble getting 
them to go as well.  Here is an example that works for me.  Also, as 
you are already doing, make sure to have a filter set to query out 
the NULL values or the expression parser will choke on them.

     CLASS
         NAME "My class"
         EXPRESSION ([CODE] = 310)
         STYLE
            COLOR 255 0 0
         END
     END


>
>
>2)  Completely unrelated to the first question: how does mapserver 
>handle Database connections (SDE in particular) with regards to 
>scalability?

If you are using MapServer in regular CGI or MapScript mode, a new 
SDE connection is made for each map request.  This can consume SDE 
connections, especially if Apache is hanging on to them for an 
HTTP_WAIT or you have many multiple requests coming in.

The other approach is to use FastCGI in combination with SDE. 
MapServer has FastCGI support thanks to Frank Warmerdam, and SDE 
supports connection/layerinfo pooling through this mechanism. 
FastCGI allows SDE to share connections and layer information so that 
subsequent requests do not require additional connections to SDE.

Even with FastCGI, however, I've found that SDE's connection count 
seems to be consumed with multiple subsequent requests because of how 
SDE does its connection accounting.  I've bumped my SDE connection 
limits high enough to not have this problem, but if you don't have 
enough licenses, or enough memory in your SDE server, this can be a 
problem.

HTH

Howard