Joins are really meant for simple look ups so there is no indexing or anything 
like that with the DBF and flat file options. Also note that JOINs are 
post-query-only so you couldn't label based on a joined column, nor query on a 
joined attribute. You could keep information you wanted to display as the 
result of a query however.

In short, if you have a relatively small set of attributes that you want to 
display as a result of a query then a JOIN might work well.  Does that help?

Steve

From: mapserver-users [mailto:[email protected]] On 
Behalf Of Mark Volz
Sent: Thursday, August 18, 2016 8:23 AM
To: [email protected]
Subject: [mapserver-users] performance question - joining dbf tables in 
MapServer

Hello,

I am considering joining my tax data to my parcel dataset on the fly using the 
MapServer Join function.  This way I can update my tax data weekly, and my 
parcels as needed.  My tax data will be in a dbf and my parcels will be in a 
shapefile.

Questions:

*         Is there any performance hit using joining on the fly vs keeping the 
tax data in the shapefile?

*         Are there any tips I should be aware about to make the joins work 
faster?

http://mapserver.org/mapfile/join.html.


Thank You!


Sincerely,
Mark Volz
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