[QGIS-Developer] The curious case of GeoPackage on exFAT

[Jonathan Moules]

Hi Bo,

Looking at the WAL docs for SQLite (https://www.sqlite.org/wal.html) 
(what geopackage is built from) I see this:

"The WAL file exists for as long as any database connection has the 
database open. Usually, the WAL file is deleted automatically when the 
last connection to the database closes. However, if the last process to 
have the database open exits without cleanly shutting down the database 
connection, or if the SQLITE_FCNTL_PERSIST_WAL file control is used, 
then the WAL file might be retained on disk after all connections to the 
database have been closed."

So it sounds like whatever the last process is to touch the GeoPackage 
may not be closing the connection cleanly on exFat.

Cheers,

Jonathan

On 2020-05-11 13:10, Bo Victor Thomsen wrote:
>
> Hi all -
>
> I have a strange problem. I'm have 3 different disk on my windows 
> based system on Mac hardware
>
>  1. My system drive. Formatted to NTFS.
>  2. A flash-drive. Formatted to FAT32.
>  3. A data drive. Formatted to exFAT. The last is my primary data
>     drive and is shared between my Windows partition and my Mac
>     partition on my MacBook Pro. Hence the use of exFAT.
>
> I have a QGIS plugin, which copies a template of a GeoPackage file to 
> "where-ever the user wants it placed" and afterward make some content 
> changes in the copy using the PyQT QSQL module with the QSPATIALITE driver
>
> This work if the Geopackage  file is copied to either disk no 1 (NTFS) 
> or disk no 2 (FAT32). However, it doesn't work if the file is copied 
> to disk no 3 (exFAT). The process leaves the WAL files even after the 
> database is closed properly.
>
> And even more strange: If I reformat the flash-drive to exFAT and 
> repeat the experiment using the reformatted drive it too works without 
> a hitch.
>
> The normal "divide et impera" method tells me that my exFat data disk 
> is bork'ed. However this error *only* occurs with the QGIS/GeoPackage 
> creation/modification scenario. Everything else is working OK.
>
> The disk is not shared on the network. Has anyone experienced the same 
> type of problems ? And have a solution ?? Just asking before I begin 
> to clean up / reformat my 100 GB data disk
>
> System setup: MacBook Pro 2014 / Windows 8.1 OS /QGIS 3.10.5 (the same 
> problem occurs with 3.10.0 , 3.10.2 ...3.12.2)
>
>
> -- 
> Med venlig hilsen / Kind regards
>
> Bo Victor Thomsen
>
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