Re: [Qgis-user] Map Software Query

[Jonathan Moules]

Hi Gaurav,

This should definitely be do-able with QGIS. It sounds like a simple 
"Point in polygon" join (or a "spatial join"). If you google that you 
should find a few tutorials.


Cheers,

Jonathan

On 22/10/2019 14:46, Gaurav Khatri wrote:


Hi,

I am trying to build a software where I can plot points by agents and 
their prospect addresses on a map.


After plotting the points I would like to draw a polygon around that 
agent and give him those particular names whose points are under that 
polygon, to the agent to work further.


Kindly let me know if this is possible to build using QGis or I should 
use some other software.


Any help is appreciated, thank you.

Regards,

Gaurav


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Re: [Qgis-user] GeoPackage deadlocks (Andrea Peri)

[Jonathan Moules]

> Two processes accessing geopackage on a local computer can run into 
the same issue. SQlite is designed for a single user.


Interesting. SQlite can most definitely handle multiple users - 
certainly reading, and for writing if it's not over the network, I 
expect the processes are breaking one (or more) of the "do this to 
corrupt your database" rules.


On 17/10/2019 11:54, Patrick Dunford wrote:
It's not a network issue and neither is it a Windows issue. Two 
processes accessing geopackage on a local computer can run into the 
same issue. SQlite is designed for a single user. It is very reliable 
when used as designed.


On 27/09/19 7:13 PM, Paul Wittle wrote:

Hi Andrea and Enrico,

Thank you for providing an answer even if it was not what I was 
hoping to hear; it was the conclusion I'd reached myself.


Has this issue been considered given the official move from shapefile 
to geopackage as the default format?


My understanding was that shapefiles could be used over a network and 
whilst multiple people editing was dangerous it did not cause deadlocks.


Combined with the issues relating to MapInfo tab files over a network 
I've got into some hot water over my attempt to get QGIS rolled out 
in our organisation now. I'm going to have to think carefully about 
my next steps as it can be difficult to educate large numbers of 
staff and the two issues mean that people using QGIS incorrectly can 
cause pretty big issues.


To summarise,
  - You open a geopackage and save to the network; someone else comes 
along and opens it in their QGIS and everything looks okay until the 
PCs deadlock...ICT help calls and data corruption may occur.
  - You open a MapInfo tab file from the network and it looks fine 
(accept that it my draw in a user projection). MapInfo user receive 
errors but this is unknown to the QGIS user...ICT help calls result.


Whilst I'm glad the forums have helped to diagnose both behaviours I 
would personally say that the issues pose a bit of a threat to 
software adoption by larger companies and institutions that may be 
using Windows networks and potentially migrating from MapInfo.


In both cases my gut feel is that the best solution might be to look 
into use detection. If GDAL (I assume) can be improved to detect that 
either file type is already open then it might be possible to simply 
ban a second user from opening the file at the same time. This might 
frustrate some users but most importantly it would make the 
application safer from an ICT perspective.


These are of course just my personal opinion from my particular use 
case so please don't be offended by them if you disagree but I'd be 
really happy to hear how others are approaching the issues and/or 
opposing views?


Many thanks,
Paul


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[Qgis-user] Geocoding issue

[Leung, Scott (MRC)]

Hi,



I'm trying to geocode various addresses, but I keep getting this error which 
says "Errno 13: permission denied."  Do you what that's about, and what I can 
do to fix it?



Thanks,



Scott

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Re: [Qgis-user] GeoPackage deadlocks

[Even Rouault]

On vendredi 25 octobre 2019 22:51:39 CEST Jésahel Benoist wrote:
> I could provide some background information as we're working for about a
> year in a multi-users (5 users) configuration mainly based on network
> shared geopackages in a Windows environment. I've tried and tested a lot of
> configurations and still looking for a near PostGIS solution only in terms
> of easiness and security.
> 
> At first, we were using SQLite and I have to say that it was good,
> especially in terms of speed. But it lacked the possibility to alter
> database schema, which was a pain.
> So I switched to Geopackage and very bad problems started.
> First as you all know was the speed problem. Sometimes, it was just
> unusable with only two users, and sometimes even with only one user,
> especially with big database, with some display locks. I discovered that
> the drawing by itself was like a concurrent user... Disabling the drawing
> restored usage, even if sometimes it needed to restart qgis.
> Then I discovered the wal problem and switched to delete mode. Speed
> problem was gone but... I got a file lock. One of my db file was then
> unusable. I had to restore it. Happily it was with the most experienced
> user and at the end of the day, and we had only one session data lost.
> So I decided to divide the biggest db to several little files and to make
> apply stricter usage rules to users to be sure that there isn't much
> concurrent access.
> For now it's usable but we still have to restart qgis sometimes. Sometimes
> the display disappears and reappears with a delay or by creating an entity.
> Note that it's the same with SQLite.
> 
> As a coder, I wonder why there isn't always a file locking mechanism with a
> threaded waiting loop, even for read access and for all file formats,
> because if you change the file content, nothing can say a read wasn't done
> at the same time, and so the read could obtain bad values. Even multiple
> threads on a single machine could access the same file anytime, so it would
> be safer to avoid this kind of problem.

To disable all locking, you can try setting the SQLITE_USE_OGR_VFS environment 
variable to YES that will switch to a custom SQLite virtual file system 
implementation (designed for GDAL /vsicurl/ mostly, but that can work with 
regular files as well), that doesn't take any lock at all. But beware: it will 
eat your children if you try to do concurrent edits, and you'll get reading 
errors if reading while editing.

Even

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Re: [Qgis-user] GeoPackage deadlocks

[Jésahel Benoist]

I could provide some background information as we're working for about a
year in a multi-users (5 users) configuration mainly based on network
shared geopackages in a Windows environment. I've tried and tested a lot of
configurations and still looking for a near PostGIS solution only in terms
of easiness and security.

At first, we were using SQLite and I have to say that it was good,
especially in terms of speed. But it lacked the possibility to alter
database schema, which was a pain.
So I switched to Geopackage and very bad problems started.
First as you all know was the speed problem. Sometimes, it was just
unusable with only two users, and sometimes even with only one user,
especially with big database, with some display locks. I discovered that
the drawing by itself was like a concurrent user... Disabling the drawing
restored usage, even if sometimes it needed to restart qgis.
Then I discovered the wal problem and switched to delete mode. Speed
problem was gone but... I got a file lock. One of my db file was then
unusable. I had to restore it. Happily it was with the most experienced
user and at the end of the day, and we had only one session data lost.
So I decided to divide the biggest db to several little files and to make
apply stricter usage rules to users to be sure that there isn't much
concurrent access.
For now it's usable but we still have to restart qgis sometimes. Sometimes
the display disappears and reappears with a delay or by creating an entity.
Note that it's the same with SQLite.

As a coder, I wonder why there isn't always a file locking mechanism with a
threaded waiting loop, even for read access and for all file formats,
because if you change the file content, nothing can say a read wasn't done
at the same time, and so the read could obtain bad values. Even multiple
threads on a single machine could access the same file anytime, so it would
be safer to avoid this kind of problem.

I do love QGIS and would be really happy to help, if I can, with my modest
capabilities.

Best regards,

Jésahel
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Re: [Qgis-user] GeoPackage deadlocks

[Even Rouault]

On vendredi 25 octobre 2019 17:10:40 CEST Matthias Kuhn wrote:
> Hi all,
> 
> We had the same experience in a project of ours. Multiple users with
> read-only access to a gpkg on a (Windows) network share. The results
> were freezes on unloading the layer (e.g. closing QGIS or opening
> another project) on system A until system B would have closed the QGIS
> layer there. The behavior seemed surprising to me and on first sight I'd
> have put it more into the category "bug" rather than "feature".
> 
> Good news, this behavior could be changed by switching the sqlite
> journal mode to delete (environment variable OGR_SQLITE_JOURNAL=DELETE).

Caution: WAL was enabled because DELETE (which is the default journal mode of 
SQLite) was causing locking issues, even in local file, single user, single 
QGIS application context. There might have been later changes in the OGR 
provider that makes it no longer needed, but this should be carefully checked. 
In particular if the test added in https://github.com/qgis/QGIS/commit/
b6b8759efbeb833d0d3dbf6df008087701361ad3#diff-17fd782357fcfed115b06d24b4416bbdR92
 
still pass in DELETE

Even

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[Qgis-user] 3D View Scaling

[Adam Dershowitz]

I’m having an issue with a 3D view, that has come up before.  I’ve simplified 
it and made a few images to explain the problem.

I sometimes work with 3D points, such as points that represent the flight of an 
aircraft.  If there are points that are over a DEM, then scaling is not handled 
as expected.  For an example, I created a few points in a layer and a polygon 
in another layer, both above a DEM layer.  I set the elevation for each of the 
points and the polygon corners to be above the DEM elevation.  I then set 
Elevation Clamping for both the points and polygon to be absolute.  If I open a 
 3D view and set the elevation to come from the dEM I get just what I would 
expect.  the points and the polygon show as just above the DEM.  



However, if I then set the vertical scale to be 2.0, for example, the polygon 
stays above the DEM, as I would expect.  But, the points end up below the DEM, 
so are no longer visible:



This seems like a bug to me.  So, changing the vertical scaling, changes the 
vertical scale of the DEM, and the corresponding height of a polygon, but it 
does not change the height of points.  

The only work around that I’ve found is to manually create a new point layer 
and make the elevation for each point twice what it actually is.  Then, if I 
view that layer in 3D, with the scale at 2.0, the points show up as I would 
expect.  I’m using version QGIS 3.8, but I’ve seen this problem in a  number of 
older versions as well.  I’ve also tried changing the settings for the layer 
from absolute to other altitude clipping,  but that doesn’t seem to help.  The 
stored altitude values for the polygon, DEM, and points are all meters above 
sea level.

Any suggestions or fixes?

Thanks,


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Re: [Qgis-user] GeoPackage deadlocks

[Matthias Kuhn]

Hi all,

We had the same experience in a project of ours. Multiple users with 
read-only access to a gpkg on a (Windows) network share. The results 
were freezes on unloading the layer (e.g. closing QGIS or opening 
another project) on system A until system B would have closed the QGIS 
layer there. The behavior seemed surprising to me and on first sight I'd 
have put it more into the category "bug" rather than "feature".


Good news, this behavior could be changed by switching the sqlite 
journal mode to delete (environment variable OGR_SQLITE_JOURNAL=DELETE).


QGIS and OGR use gpkg in WAL mode by default. Fun fact: this is not 
supported on network drives, as documented on 
https://www.sqlite.org/wal.html :


> All processes using a database must be on the same host computer; WAL 
does not work over a network filesystem


I did not test what happens if only *some* of the accessing systems use 
DELETE and others use WAL, nor did I check what happens when writing to 
the DB while reading (or even concurrent writes - which definitely no 
longer is a safe operation mode for sqlite on a shared network volume <- 
if you end up in this category, get a postgres server).


Maybe we need to rethink the default mode of opening gpkg's
and if anyone can provide ground truth on the untested operation modes 
mentioned before, please share the results here.


Bests, Matthias

On 10/18/19 8:17 AM, Chavoux Luyt wrote:

Hi,

Just my two cents... this is IMHO exactly where postGIS will shine. 
Using PostgreSQL as backend will avoid any of these issues (i.e. 
prevent data corruption). For my personal projects I have never 
bothered with it, so I cannot say how easy it is to set up, but once 
it is up and running PostgreSQL is one of the most reliable database 
servers out there.


Cheers,
Chavoux

On Thu, 17 Oct 2019, 21:01 , -- Forwarded message --

From: Francesco Pelullo mailto:f.pelu...@gmail.com>>
To: Patrick Dunford mailto:enzedrailm...@gmail.com>>
Cc: qgis-user@lists.osgeo.org 
Bcc:
Date: Thu, 17 Oct 2019 13:09:43 +0200
Subject: Re: [Qgis-user] GeoPackage deadlocks (Andrea Peri)


Il gio 17 ott 2019, 12:54 Patrick Dunford mailto:enzedrailm...@gmail.com>> ha scritto:

It's not a network issue and neither is it a Windows issue. Two
processes accessing geopackage on a local computer can run
into the same
issue. SQlite is designed for a single user. It is very
reliable when
used as 



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Re: [Qgis-user] QGIS Server - Click Tolerance for GetFeatureInfo Requests

[Charlotte Toma (WhereGroup)]

Hello Alessandro,

thanks - this is exactly what i was looking for!

Can you define the FI_POINT_TOLERANCE, FI_LINE_TOLERANCE or
FI_POLYGON_TOLERANCE in the project settings or your qgs-file?

As far as I understand the documentation you can only add this parameter
when you make an GetFeatureInfo requests, but I would like to add this
parameter as a default value (like version/layers/e.g).

Another question: Is it possible to use the MAPTIP instead of the normal
attribute fields (e.g. ONLY_MAPTIP=true)? If you activate the function
(WITH_MAPTIP=true), then it is at the end of the table as a new column -
but i want it without the rest of the attribute columns for my wms.

Greetings,
Charly

Am 25.10.19 um 09:46 schrieb Alessandro Pasotti:
>
>
> On Fri, Oct 25, 2019 at 9:41 AM Charlotte Toma (WhereGroup)
> mailto:charlotte.t...@wheregroup.com>>
> wrote:
>
>
> Hello everybody,
>
> I would like to know if you can increase the click tolerance for the
> GetFeatureInfo query from QGIS Server.
>
> I created some WMS and would like to change the sensitivity for point
> based queries. I only know how to do that with Mapserver
> (TOLERANCE)...
>
> I am looking forward to your feedback and thanks!
>
> Charly
>
>
>
> Hi Charly,
>
> isn't the answer to your question in the documentation?
>
> https://docs.qgis.org/3.4/en/docs/user_manual/working_with_ogc/server/services.html#getfeatureinfo
>
> If you had any problem finding the documentation then please let us know.
>
>
>
> -- 
> ***
> Where2B Konferenz 2019
> 12. Dezember 2019 in Bonn
> where2b-conference.com 
> ***
>
> Charlotte Toma
> GIS-Consultant
> WhereGroup GmbH
> Eifelstraße 7
> 53119 Bonn
> Germany
>
> Fon: +49 (0)228 / 90 90 38 - 24
> Fax: +49 (0)228 / 90 90 38 - 11
>
> i...@wheregroup.com 
> www.wheregroup.com 
> Geschäftsführer:
> Olaf Knopp, Peter Stamm
> Amtsgericht Bonn, HRB 9885
>
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>
>
> -- 
> Alessandro Pasotti
> w3:   www.itopen.it 

-- 
***
Where2B Konferenz 2019
12. Dezember 2019 in Bonn
where2b-conference.com
*** 

Charlotte Toma
GIS-Consultant
WhereGroup GmbH
Eifelstraße 7
53119 Bonn
Germany

Fon: +49 (0)228 / 90 90 38 - 24
Fax: +49 (0)228 / 90 90 38 - 11

i...@wheregroup.com
www.wheregroup.com
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Re: [Qgis-user] QGIS Server - Click Tolerance for GetFeatureInfo Requests

[Alessandro Pasotti]

On Fri, Oct 25, 2019 at 9:41 AM Charlotte Toma (WhereGroup) <
charlotte.t...@wheregroup.com> wrote:

>
> Hello everybody,
>
> I would like to know if you can increase the click tolerance for the
> GetFeatureInfo query from QGIS Server.
>
> I created some WMS and would like to change the sensitivity for point
> based queries. I only know how to do that with Mapserver (TOLERANCE)...
>
> I am looking forward to your feedback and thanks!
>
> Charly
>


Hi Charly,

isn't the answer to your question in the documentation?

https://docs.qgis.org/3.4/en/docs/user_manual/working_with_ogc/server/services.html#getfeatureinfo

If you had any problem finding the documentation then please let us know.



> --
> ***
> Where2B Konferenz 2019
> 12. Dezember 2019 in Bonn
> where2b-conference.com
> ***
>
> Charlotte Toma
> GIS-Consultant
> WhereGroup GmbH
> Eifelstraße 7
> 53119 Bonn
> Germany
>
> Fon: +49 (0)228 / 90 90 38 - 24
> Fax: +49 (0)228 / 90 90 38 - 11
>
> i...@wheregroup.com
> www.wheregroup.com
> Geschäftsführer:
> Olaf Knopp, Peter Stamm
> Amtsgericht Bonn, HRB 9885
>
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[Qgis-user] QGIS Server - Click Tolerance for GetFeatureInfo Requests

[Charlotte Toma (WhereGroup)]

Hello everybody,

I would like to know if you can increase the click tolerance for the
GetFeatureInfo query from QGIS Server.

I created some WMS and would like to change the sensitivity for point
based queries. I only know how to do that with Mapserver (TOLERANCE)...

I am looking forward to your feedback and thanks!

Charly

-- 
***
Where2B Konferenz 2019
12. Dezember 2019 in Bonn
where2b-conference.com
*** 

Charlotte Toma
GIS-Consultant
WhereGroup GmbH
Eifelstraße 7
53119 Bonn
Germany

Fon: +49 (0)228 / 90 90 38 - 24
Fax: +49 (0)228 / 90 90 38 - 11

i...@wheregroup.com
www.wheregroup.com
Geschäftsführer:
Olaf Knopp, Peter Stamm 
Amtsgericht Bonn, HRB 9885



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