[Mapserver-users] Fastest Data Format

[Jan Hartmann]

I just got connection pooling running (Happy New Year!), but I can only
test it against PostGIS here. As expected, it doesn't make much
difference there (17 vs 14 seconds for a map with 100 layers), but for
SDE and OracleSpatial it should cut substantially more ice. I'll send
the code to Steve Lime and the PostGIS and OS folks for testing and if
they agree it can be put into CVS. Unless I made some terrible mistake
this should not take much time: the whole thing takes about 50 lines in
the main code and about 5 lines for each of the database interfaces.
Moreover, there is no need to change all database interfaces at the same 
time: an unchanged interface will run as before.

Note however that connections are pooled ONLY within a single map (i.e.
a single MapServer request). Every new map (e.g. for zoom or pan) has to
open a new connection (which will be used subsequently for all layers in
that map). I'm not sure if this will be adequate for SDE and OS. At
first sight, I have no idea how to keep open a connection between map
requests. Do people know how ArcIMS/SDE and OS manage this (if they do
it at all)?

Jan

Paul Ramsey wrote:
> 
> ArcIMS seems to handle SDE just fine, but that should be no surprise :) 
> I imagine that ArcIMS uses connection pooling to avoid the overhead 
> associated with making SDE connections.
> 
> I should reiterate at this point that the performance problem does not 
> adhere to SDE necessarily or to Mapserver necessarily, but to the amount 
> of time it takes to negotiate a connection with an SDE server. Once the 
> connection is made, everything is performant. It is making the 
> connection which is the issue. If you are only making one connection, 
> probably it is completely reasonable.
> 
> However, the current design of Mapserver treats each layer as a distinct 
> entity, and each layer datasource as a distinct entity. So for each 
> SDE-based layer, there is a separate SDE connection to be made. Over 
> numerous layers, things can add up to quite a long delay.
> 
> Jan Hartmann has made a proposal for connection pooling between layers, 
> I do not know if he has a preliminary implementation or if such an 
> implementation will be included in 3.7.
> 
> Paul
> 
> Martin, Daniel wrote:
> 
>> I'm curious, does another GIS product access SDE faster than MapServer?
>>
>> The reason I ask is that I also experience slower performance using 
>> MapInfo
>> data via OGR.  Certainly I realize MapInfo data isn't nearly as robust as
>> SDE.  However, MapServer serves the same map quicker than MapInfo's 
>> own GUI
>> application.  I can't ask for much more than that.
>>
>> -Dan
> 
> 
> 
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