Hi,

I looks like it was something to do with the hybrid indexing method. I used the 
python code in the previous reply and presto...it works.

We had already checked and there was nothing wrong with the speed of the data 
load. You turn the layer on and it is pretty much instantly displayed so I'm 
guessing something with the way it calculates the index was the issue.

I'm told it was voted that the option should not be added to the settings 
because it would confuse people. Personally I think you should be more 
concerned about users out there who might experience similar performance and 
never mention it; potentially deciding to use other software as well.

We had been putting up with the slow performance till now but that single 
setting makes QGIS runs super-fast and smooth.

My opinion is just that, my opinion, but I hope that those discussing it will 
consider making the default something that can be configured in the global 
settings ui file. Alternatively it might be worth investigating why the hybrid 
method is so slow and just fixing that. They really are not comparable in our 
install, one is instantly available and the other takes literally 5 minutes!

Many thanks for the help everyone; I'm really really pleased with the 
performance now! 😊

Paul

-----Original Message-----
From: Philip Barlow <phil...@pembrokeshirecoast.org.uk>
Sent: 22 January 2021 13:39
To: Paul Wittle <p.wit...@dorsetcc.gov.uk>; Julien Cabieces 
<julien.cabie...@oslandia.com>
Cc: qgis-user@lists.osgeo.org
Subject: RE: [Qgis-user] Snapping tools really slow

Hi Paul,

What sort of database are you using?  MSSQL or Postgres?

We're on Postgres13 and PostGIS 3.0. A quick test with QGIS 3.10.14 digitising 
to OSMM... there is a small delay but its only around a second or two. You may 
have a larger extent than me in your database though? Mine is just the whole of 
the County of Pembrokeshire.  I haven't tried 3.16 to see if there is any 
noticeable difference.

Regards

Phil



-----Original Message-----
From: Qgis-user <qgis-user-boun...@lists.osgeo.org> On Behalf Of Paul Wittle
Sent: 22 January 2021 08:10
To: Julien Cabieces <julien.cabie...@oslandia.com>
Cc: qgis-user@lists.osgeo.org
Subject: Re: [Qgis-user] Snapping tools really slow

Hi,

It might be best if I screen record you a video of it loading so you can see 
the performance issue as it is always difficult to discuss in text. I'll have 
to send that to you offline from this thread as I believe videos aren't 
supported by this group.

We are snapping to Ordnance Survey MasterMap because we work in the public 
sector and are permitted to do so for council business. Depending on licencing 
you may not be able to access the same level of OS data as you would probably 
have to pay for it (assuming your company is private) so I guess that would not 
be helpful in terms of replicating the issue. That said; I also tried it using 
the OS Maps API (WFS) and it was also slow so OS may be able to share that with 
you for test purposes.

In the older version 3.10 the progress bar always disappeared for some reason 
so it appeared to just hand whilst the index builds. In the new version a blue 
bar appears at the bottom but it is not a loading bar it is the one you get 
when the application doesn't know how long is left. I tried to stop the process 
because it was long running and it said 'Indexing' was running did I want to 
try and stop the process so I'm pretty sure it is the indexing that is not 
working for some reason.

Is there a way to pre-build the snapping index?

It works fine for smaller layers, things we create etc. If I can resolve this 
one layer then all my problems go away so we would be really happy to pre-cache 
the snapping index if that is possible.

Thanks,
Paul

-----Original Message-----
From: Julien Cabieces <julien.cabie...@oslandia.com>
Sent: 22 January 2021 05:32
To: Paul Wittle <p.wit...@dorsetcc.gov.uk>
Cc: qgis-user@lists.osgeo.org
Subject: Re: [Qgis-user] Snapping tools really slow


Hi,

I made quick tests with some dataset and I failed to see any performance issues.

Could you create an issue with some data sample and project?

Is it the index building that take a long time (there is a progress bar 
displayed at the bottom of the map close to the mouse coordinate information 
while index is currently building) or is it when you move your cursor on the 
map that the snaping information takes time to appear. Or is it when you pan 
the map?

You can enable snapping for specific range of scale, avoiding building index at 
very large scale where snapping is useless.

Regards,
Julien



> Hi,
>
> I've been using version 3.10 and 3.16 and I notice that enabling snapping is 
> extremely slow and oddly significantly slower on 3.16 than 3.10. We thought 
> it might be downloading the dataset on screen but discovered the data is back 
> from the database within seconds and the delay is because QGIS is building an 
> index.
>
> Why is it so inefficient and is there anything that can be done to get better 
> performance?
>
> It is really slow and we are trying to transfer users from MapInfo / ESRI so 
> they will not like the performance at the moment.
>
> To be clear the data has a primary key, spatial indices and all is of good 
> quality. As I say the data downloads and displays within seconds on the map; 
> is it because I've selected snapping to segment as well as vertex?
>
> Thanks,
>
> Paul Wittle
> [cid:image001.jpg@01D6F016.C23D1CA0]<https://www.dorsetcouncil.gov.uk/
> >
> Business Solutions Analyst (GIS)
> ICT Operations
> Dorset Council
> 01305 228473
> <tel:01305%20228473%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20
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>
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