Hi,
This should be IMHO an issue of highest priority for QGIS.
Jésahel wrote
> I've created a script to deactivate wal on samba shares, because samba is the
> main issue.
> It contains this only line : QSettings().setValue("/qgis/walForSqlite3",
> False)
That's interesting. Are you sure it's Samba?
SQLite FAQ [2] confirms that NFS has problems.
Did not find issues on Samba, but file locking with fcntl is mentioned here [3].
Goal should IMHO be that 1. No crash, 2. read-only multi-user access
should be possible and 3. writing users must be warned if QGIS isn't
able to exclusively open the file.
And Jésahel script suggests, that at least point 1 and 2 are possible.
Andreas wrote:
> Unfortunately it is a known issue that Geopackages and QGIS are bad at
> handling simultaneous write and even read requests
> and developers are working on finding solutions (hopefully soon).
The only issue I find on QGIS tracker is [1]. Am I missing something?
:Stefan
[1] https://github.com/qgis/QGIS/issues/23991
[2] https://www.sqlite.org/faq.html#q5
[3] https://www.samba.org/samba/docs/old/Samba3-HOWTO/locking.html
Am Mi., 6. Mai 2020 um 10:42 Uhr schrieb Jésahel Benoist <[email protected]>:
>
> Hi Bruno,
>
> I've worked a lot on this issue for two years now. I've started with sqlite
> (that was faster and better) but finally I decided to migrate to geopackage.
> It was painful at first but now it's OK. But it needs some rules.
>
> First, I've broken the original big geopackage files into smaller ones. The
> users are advised to work only one by one on a specific thematic/file (read
> access is possible).
> I've created a script to deactivate wal on samba shares, because samba is the
> main issue. It contains this only line :
> QSettings().setValue("/qgis/walForSqlite3", False)
> You should download some tools like Spatialite_GUI and SQLiteDatabaseBrowser
> so that you can really work on the db and have better control. QGIS's
> dbmanager is a bit limited and sometimes buggy for sqlite/geopackage,
> especially with special chars.
> Try to work with QGIS internal explorer, it's a tool that has good
> export/import functions.
> Backup files at least one time a day !
>
> Now with the covid I have created my own online postgis server so that we can
> work at home without "help" of IT department and it's GREAT. Multi-user,
> faster, smaller, stronger (lol). And some nice capabilities like spatial
> filtering ! I highly recommend this.
>
> Questions for all : I've recently discovered this
> https://gdal.org/user/virtual_file_systems.html#virtual-file-systems
> Wouldn't it be possible to avoid samba's multi-users bug with vsi ?
>
> Jésahel
>
>
>
> Le mer. 6 mai 2020 à 09:12, Andreas Neumann <[email protected]> a écrit :
>>
>> Hi Bruno,
>>
>> Unfortunately it is a known issue that Geopackages and QGIS are bad at
>> handling simultaneous write and even read requests and developers are
>> working on finding solutions (hopefully soon). In single user scenarios
>> Geopackages are fine. But Multiuser must be avoided, even for reading only,
>> unfortunately.
>>
>> As to PostgreSQL vs. Postgis: Postgis is the spatial extension of
>> PostgreSQL. If you need geometries (which I assume) than you will need
>> Postgis.
>>
>> Andreas
>>
>> Am 06.05.20 um 08:58 schrieb [email protected]:
>>
>> Hi
>>
>> In my company we are five people who sometimes work with GIS, and we are
>> moving from ArcGIS to QGIS (how cool is QGIS and SLYR!) and in this context
>> from ESRI file geodatabase to geopackage. Today we run into serious issues
>> when two people worked with the same geopackage. I was aware, that it is
>> dangerous and unwise to edit the same geopackage from two different
>> computers at the same time. But I did not expect both QGIS applications to
>> crash immediately and the geopackage to get corrupted. I hoped to get a
>> warning or simply not be able to enter edit mode (We later found out, that
>> the corrupted geopackage could be recoveredby by adding a new table, this
>> somehow fixed it. Whew!).
>>
>> Worse, I found that the same thing happens, when I open a QGIS project with
>> a layer from a geopackage for display only (no edit mode), which is being
>> edited by an other user on an other computer. Again, both QGIS application
>> crashed immediately with data loss. Again, the non-responsive QGIS tasks
>> could not be killed by windows taskmanager, only by restarting of the
>> computers.
>>
>> We are using QGIS 3.12.2 on Windows 10. The Geopackages are located on a
>> samba network share.
>>
>> My questions:
>>
>> 1. Is this setup that bad? Do you experience the same fatal consequences if
>> someone loads a layer from a geopackage which is being edited by someone
>> else? Is there something I do wrong or I that can do to improve the
>> situation?
>>
>> 2. I realize, that we should probably move from geopackage to a database. Do
>> we need PostGIS or can we use PostgreSQL? We don't need more functinality
>> than a geopackage offers (exept multi user read/edit possibility and
>> stability).
>>
>> Many thanks for some hints that put me in the right direction!
>>
>> Bruno
>>
>>
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