[mapserver-users] File Format Performance

[Stephen Woodbridge]

Flavio Hendry wrote:
> Hi Ian
> 
>> 1. Are ESRI Shape files the best file format for MapServer?
> 
> For smaller area yes. However I did not see a big difference between 
> Shape and MapInfo. Use shapeindex for larger files.

Unless something has changed, mapserver used to build a temporary 
shapeindex on the fly and discard it if one did not exist. In general if 
you are using shapefiles, you should always create shapeindexes.

>> 2.      Will storing all my data in PostgreSQL be faster (at rendering 
>> with php_mapscript) than ESRI Shape files?
> 
> Should be similar, maybe slightly slower. We use PostGIS for very large 
> site (gigabytes of vector data). Performance is pretty good, however I 
> would suggest quadcores and Linux 64. I would not like to fiddle around 
> with such large shapefiles and I do not like the idea of tiling the data .

As has been said, if you are displaying all or most all the data in the 
data set then shapefiles will be faster than Postgres. If you are zoomed 
in to a small percentage of your data then Postgres will likely be faster.

Tiling your shapefiles is also a good option for many people that are 
deploying mapping data that is not highly dynamic. Tiling breaks huge 
shapefiles into multiple smaller shapefiles, that can be re assembled 
using a tileindex. The goal of tiling is to organize data into files 
such that if mapserver needs to open the file, then most of the data in 
the file is consumed. If you data is highly dynamic, then postgres is 
highly recommended.

>> 3. Is there another options that is better (faster) than PostgreSQL or 
>> Shape files (e.g. another file format)?
> 
> MapInfo is pretty good too ... suggested if you are a MapInfo User.

One of the reasons mapserver is so good with shapefiles is that it has 
native support for shapefiles. Most other file formats go through a 
GDAL/OGR interface to access the data. While this is very efficient it 
is still more overhead than direct access to the shapefiles. Database 
connection pay an over head in making the connection and in transferring 
the data across that connection, but has the benefit of better indexing 
and page management which can offset the connection costs in some cases.

Best regards,
   Steve W.

> Mit freundlichem Gruss / Best regards
> Flavio Hendry
> 
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