[OpenLayers-Users] WFS Layers blocks excution?

[Jackey Cheung]

I don't know how OL sends out queries. If tile by tile with proper bbox, 
there should be less than 100 (max.) pairs per tile; if it queries the whole 
display area, there should be less than 1000 (avg.) pairs. However, besides 
the coordinate, two more attribute data is queried, but I don't see any 
impact by that.

I've tried traced into OL a little bit, it seems each time I refresh or pan 
the map, there will be multiple queries being sent, on my 1440x900 IE, it's 
around 29~30 queries each time, each query returns around 10~15 records 
(I've set a limit of 10 in the query statement), and it takes more 1~2 
seconds to process the XML of each of the result sets. If I get it right, 
the XML processing is the cause of the lag, but if that's true, I don't see 
any possible on my side to improve the performance, unless I do some coding 
in OL.

F.Y.I. I'm running on a P4D 3GHz, 1GB RAM, and IE6 sp2, with PNG as map 
image, and GIF as marker icons.

BTW, the same test on FireFox shown different results. Unlike IE, which lags 
while moving (panning) the map, with newly revealed tiles shows up normally. 
On FireFox, the map moves (panning) smoothly, while newly revealed tiles is 
shown up significantly delayed.


----- Original Message -----
From: "Christopher Schmidt" <crschmidt at metacarta.com>
To: "Jackey Cheung" <cheung.jackey at gmail.com>
Cc: <users at openlayers.org>
Sent: Monday, June 04, 2007 23:18
Subject: Re: [OpenLayers-Users] WFS Layers blocks excution?

> On Mon, Jun 04, 2007 at 11:36:20AM +0800, Jackey Cheung wrote:
>> Greetings!
>>
>> I've been massing around with OL for a while. Lately, I've tried to open 
>> a WFS layer to my map. Once it's added, the IE hangs for minutes while 
>> refreshing the entire page, and panning the map is painfully laggy. What 
>> is the cause of this lag?
>
> OpenLayers vector support is designed to support the display of ~50->100
> features, in the range of 2000-5000 coordinate pairs. How much data are
> you attempting to load?
>
> Regards,
> -- 
> Christopher Schmidt
> MetaCarta