Gregor Mosheh wrote:
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)
If the data is really in 5 separate layers, splitting the data into
those 5 layers would greatly help. You can also FILTER the data for the
LAYER which will help some but not as much as splitting the data.
You can load and dump the shapefiles into postGIS or Oracle and filter
the data when you dump it to be only that what you need for the specific
layers. Its a little work up front byt will help with performance. Or
you can write a mapscript routine to read, filter and write new shape
files for the layers you need.
-Steve W
