[gdal-dev] [EXTERNAL] Re: Is SQLITE dialect supported on Memory OGR datasets?

[Even Rouault]

If the /vsimem/... file hasn't been created, then it won't be opened. 
This is like a regular file system

If you want to copy an existing file to /vsimem/, you can do something like

gdal.FileFromMemBuffer("/vsimem/foo.gpkg", open("source.gpkg", "rb").read())

do something

gdal.Unlink("/vsimem/foo.gpkg")

or you can ogr.GetDriverByName(...).CreataDataSource("/vsimem/foo") to 
create a new one

Even

Le 22/08/2023 à 16:11, Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS AND 
APPLICATIONS INC] via gdal-dev a écrit :
>
> As per your workaround suggestion,
>
> Are these intended to work?  The returned datasource is None.  
> Removing the `/vsimem` preamble returns the disk-backed geopackage 
> datasource as expected.
>
> tree_canopy_mem_ds 
> =ogr.Open('/vsimem/Users/jrmeyer3/Downloads/features.gpkg')
>
> tree_canopy_mem_ds 
> =ogr.GetDriverByName("GPKG").Open('/vsimem/Users/jrmeyer3/Downloads/features.gpkg')
>
> *From: *Even Rouault <even.rouault at spatialys.com>
> *Date: *Monday, August 21, 2023 at 6:22 PM
> *To: *"Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS AND APPLICATIONS 
> INC]" <jesse.r.meyer at nasa.gov>, "gdal-dev at lists.osgeo.org" 
> <gdal-dev at lists.osgeo.org>
> *Subject: *[EXTERNAL] Re: [gdal-dev] Is SQLITE dialect supported on 
> Memory OGR datasets?
>
> *CAUTION:*This email originated from outside of NASA.  Please take 
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>
>
> Jesse,
>
> No it wasn't. Fix in https://github.com/OSGeo/gdal/pull/8247
>
> Potential workaround: use a in-memory SQLite or GeoPackage with a 
> /vsimem/ filename
>
> Even
>
> Le 21/08/2023 à 21:30, Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS 
> AND APPLICATIONS INC] via gdal-dev a écrit :
>
>     Hi,
>
>     This works:
>
>     tc_lyr =execute_SQL(tree_canopy_mem_ds,"select * from
>     trees",/spatialFilter/=c_geo)
>
>     However, this:
>
>     tc_lyr =execute_SQL(tree_canopy_mem_ds,"select * from
>     trees",/spatialFilter/=c_geo,/dialect/="SQLITE")
>
>     Returns:
>
>     In Initialize(): sqlite3_step(SELECT _rowid_, * FROM 'trees' LIMIT
>     1): SQL logic error
>
>     Where execute_SQL = ogr.DataSource.ExecuteSQL
>
>     Which is naturally a surprise given that I’m not explicitly asking
>     for the rowid, nor to limit the number of returned rows.
>
>     The docs claim that the SQLite dialect can be used with any OGR
>     datasource, so I did expect this to work.  The input datasource is
>     GeoPackage, which is based on SQLite, so I assume my install is
>     built with SQLite, though I’d welcome advice on how to explicitly
>     demonstrate this.
>
>     My GDAL version install is 3.6.4, on OSX 13.5.
>
>     Thanks,
>
>     Jesse
>
>
>
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