[Qgis-psc] [QGIS-Developer] (QGIS 2020 Grant Report) Use of FileGeodatabase spatial index in OpenFileGDB driver

[Matthias Kuhn]

Impressive numbers.
Thanks for the work, Even!

Matthias

On Mon, Sep 28, 2020 at 10:29 PM Even Rouault <even.rouault at spatialys.com>
wrote:

> Hi,
>
>
>
> I want to report about the outcome of
>
> https://github.com/qgis/QGIS-Enhancement-Proposals/issues/172
>
> "Use of FileGeodatabase spatial index in OpenFileGDB driver"
>
>
>
> This work has been successfully completed into GDAL master (for upcoming
> GDAL 3.2) per https://github.com/OSGeo/gdal/pull/2771 , and automatically
> benefits to QGIS when it uses the OpenFileGDB driver.
>
>
>
> Some figures on a version from of few years ago of the dataset at
>
> https://data.linz.govt.nz/layer/50772-nz-primary-parcels/, featuring 2
> 484 646 polygons, 773 MB:
> "ogrinfo -spat 174.949909 -41.143842 175.684529 -40.594600 -al -so
> -noextent" (thus counting the number of features intersecting the spatial
> filter), which returns 81 046 polygons, nows runs in 400 ms with GDAL
> 3.2dev and the OpenFileGDB driver, versus 6.7 s before (full scan), vs 890
> ms with the FileGDB driver (with FileGDB SDK 1.5).
>
> All figures given with debug builds, and on a hot run (so with most pages
> cached by the OS).
>
>
>
> Interactive display of this dataset in QGIS with the OpenFileGDB driver is
> as fluid as with the FileGDB one. Comparing behaviour of OpenFileGDB and
> FileGDB drivers with strace shows that they read a similar amount of data
> in the .spx file, which confirms it is uses correctly.
>
>
>
> The filegdb reverse engineered specification was also updated in
>
>
> https://github.com/rouault/dump_gdbtable/wiki/FGDB-Spec#specification-of-spx-files
>
>
>
> Thanks to qgis.org grant program for making this improvement possible.
>
>
>
> Best regards,
>
>
>
> Even
>
>
>
> --
>
> Spatialys - Geospatial professional services
>
> http://www.spatialys.com
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