[gdal-dev] Reading SQLite in WAL mode as read-only

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[gdal-dev] Reading SQLite in WAL mode as read-only

jratike80
Hi,

I saw this changeset https://trac.osgeo.org/gdal/changeset/37594 and started to think that how  GDAL is reading SQLite db that is in WAL journal mode from zip, tar, vsicurl or from non-writeble directory if it is documented to be generally not possible http://www.sqlite.org/draft/wal.html?

-Jukka Rahkonen-
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Re: Reading SQLite in WAL mode as read-only

Even Rouault-2

On samedi 4 mars 2017 16:26:35 CET Rahkonen Jukka (MML) wrote:

> Hi,

>

> I saw this changeset https://trac.osgeo.org/gdal/changeset/37594 and started

> to think that how GDAL is reading SQLite db that is in WAL journal mode

> from zip, tar, vsicurl or from non-writeble directory if it is documented

> to be generally not possible http://www.sqlite.org/draft/wal.html?

 

The official page is at

https://www.sqlite.org/wal.html

 

"5. It is not possible to open read-only WAL databases. The opening process must have write privileges for "-shm" wal-index shared memory file associated with the database, if that file exists, or else write access on the directory containing the database file if the "-shm" file does not exist. "

 

I'm trying to optimize the speed of

ogrinfo -ro /vsitar/my.tar.gz/my.gpkg

on very large files

(but it turns out to be much more involved, since it requires system records to be contained at the beginning of the file)

 

--

Spatialys - Geospatial professional services

http://www.spatialys.com


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