[Qgis-user] columns in spatialite

[Even Rouault]

Le jeudi 12 novembre 2015 19:25:20, Alex M a écrit :
> SQLite stores the geometries differently than Spatialite.
> http://www.gdal.org/drv_sqlite.html
> FORMAivT=WKB/WKT/SPATIALITE
> 
> Biggest side effect I can think of is that you can't use the spatialite
> query mechanisms on WKB/WKT without converting. Which includes spatial
> indexes (not sure anything in QGIS utilizes these currently). I'm also
> not sure that SQLite files via OGR are even editable (never tried). If I
> recall QGIS has a spatialite driver built in and does not use the OGR
> one in order to access more of the features.

The OGR spatialite driver has editing capabilities (when linked against 
libspatialite, otherwise read-only), as well as use of spatial indices. I'm 
not sure which capabilities the QGIS builtin spatialite driver would have in 
addition. I guess the existence of both is more due to historical reasons than 
technical ones.

> 
> I'm sure someone else will know more.
> 
> -Alex
> 
> On 11/12/2015 10:17 AM, Bernd Vogelgesang wrote:
> > Am 12.11.2015, 17:49 Uhr, schrieb Andrea Peri <aperi2007 at gmail.com>:
> >> You need study better the spatialite formats.
> >> 
> >> :)
> >> 
> >> Also the shapefile format and also the geopackage format.
> >> So you will be able to understand why spatialite is 4mb and other not.
> >> 
> >> :))
> >> 
> >> A.
> > 
> > Well, this time I didn't refer to the difference between GeoPackage and
> > SpatiaLite, but between what is called "spatialite" and "sqlite" in the
> > Save as .. dialog in QGIS.
> > 
> > The sqlite files are really small. For normal work where people do not
> > need to set up views or whatever db internal stuff,  but just want to
> > get intermediate results while working with data, and have long column
> > names and unrestricted field lengths, those sqlite files seem to be so
> > much better usable than standard ESRI shapes.
> > 
> > So again, what would be the caveats using this small sqlite stuff as
> > default? (Besides the column resorting/renaming stuff for which
> > workarounds/fixes see to be available)?
> > 
> > Cheers
> > Bernd
> > 
> >> Example: a shapefile point layer with quite some attributes and 999
> >> 
> >>> features
> >>> has 4.4 MB
> >>> saving this as spatialiate: 4.6 MB
> >>> saving as sqlite: 86 kB !
> >>> 
> >>> The sqlite file is 5 times smaller than the ESRI shape file while the
> >>> spatialite file is about the same as the shape.
> >>> 
> >>> Here on 2.8.3 at the office I have no geopackage option to test with.
> >>> 
> >>> So, whats the difference between sqlite and spatialite in detail?
> >>> 
> >>> Cheers
> >>> Bernd
> 
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