Minimizing processing at runtime can only help. If you have the disk space and your data is static, you could pre-create different layers based on your expression criteria, so that your data doesn't have to be evaluated in five different layers.
I don't know if it is still true, but regular expressions used to be faster than logical expressions, so you could add another column, pre-classify your data and store a class value in that column, something like a single-digit integer from 1-5. That might evaluate faster than a complex logical expression. David. -----Original Message----- From: UMN MapServer Users List [mailto:[EMAIL PROTECTED] On Behalf Of Gregor Mosheh Sent: Tuesday, August 07, 2007 12:33 PM To: [email protected] Subject: Re: [UMN_MAPSERVER-USERS] MapServer Performance Tips > I'm not sure if having those as shapefiles is best and what else I > should do to improve those Shapefile is a pretty fast format. Hard to beat. > about 75+ shapefiles that I've brought together as one layer using a > tile index. Also, I'm needing to break up the combined layer into 5 > layers using expressions. The size of each shapefile is between a few > MB and up around 100MB. Doesn't sound like a major problem. We deal with stuff on that order all the time and get good performance. Of course, 8 CPUs and a boatload of RAM help. Did you shptree all of the shapefiles, including the tileindex? That can help a lot. There's also "sortshp" which physically sorts the file so that seeks aren't as random. (I should add that to the page.) Beyond that, it's hard to give any specific advice without any specific details. Are you experiencing a problem with speed, or just looking to make fast even faster? Is a specific layer being problematic? Could you perhaps make the expressions more efficient, maybe merge some layers together using expressions? (you had said that you broke it into layers by expression, thought I'd ask) -- Gregor Mosheh / Greg Allensworth System Administrator, HostGIS cartographic development & hosting services http://www.HostGIS.com/ "Remember that no one cares if you can back up, only if you can restore." - AMANDA
