[Qgis-user] [QGIS-Developer] Bug with GeoPackage and Expressions?

[C Hamilton]

Ultimately what I am trying to do is to revamp the Search Layers plugin (
https://plugins.qgis.org/plugins/searchlayers/) to allow searching using
two different strings with NOT, AND, OR operators, case dependent or
independent, with qualifiers where the strings are an exact match, within
the string, begins with, and ends with. The plugin allows for searching
across all layers and all attributes, or optionally a particular layer and
attribute. The two strings may be required to match within each attribute
or match in any of the attributes within the feature. I am trying to make
it very flexible and easy to use. I know that QGIS has the Locator
interface, but the users like the extra interactivity that Search Layers
provides.

Here is the issue: For some of the searches I am creating a regular
expression that matches the search parameters and iterating through each
feature and then each attribute using *re.search* to do the comparison.
Unfortunately, this is very slow. On a 2.2 million data set it can take
5-10 minutes to do the search. This is way too slow. The SQL search is less
than 5 seconds. I am using a *QgsFeatureRequest *and then setting
*request.setFilterExpression*. I am only using this when searching on a
single layer and single attribute and I don't think there is the
flexibility that there is with the regular expressions, but I don't really
use SQL and don't know what is possible. It sounds like the SQL searching
may be limited by the vector file type source.

Are there any other ways for searching that I am unaware of? The results of
the search need to identify the feature in the layer and what attribute or
attributes matched for each of the two strings and then I can apply the
NOT, AND, OR operators. I am trying to satisfy user's requests to make
Search Layers into what they want it to be and am finding it difficult to
satisfy speed, vector file types, and flexibility. I welcome any
suggestions. Ultimately I might just have to constrain the file types
supported and say to convert the data first.

Thanks,

Calvin

On Thu, Jul 29, 2021 at 1:42 AM Nyall Dawson <nyall.dawson at gmail.com> wrote:

> On Thu, 29 Jul 2021 at 15:31, Matthias Kuhn <matthias at opengis.ch> wrote:
> >
> > Can you fill a bug for this? The expression compiler in QGIS should not
> forward it to ogr/gpkg/sqlite in this case.
>
> My interpretation is that Calvin is setting a layer filter, so QGIS
> expressions aren't involved (i.e. no bug).
>
> Nyall
>
> >
> > Matthias
> >
> > On Wed, Jul 28, 2021 at 10:08 PM C Hamilton <adenaculture at gmail.com>
> wrote:
> >>
> >> Thanks everyone for that explanation. This does complicate the ability
> to set an expression filter in a plugin when it depends on the data source
> type. I'm not sure what to do about that.
> >>
> >> Regards,
> >> Calvin
> >>
> >> On Wed, Jul 28, 2021 at 8:00 PM Anita Graser <anitagraser at gmx.at>
> wrote:
> >>>
> >>> Hi Calvin,
> >>>
> >>> 28 Jul 2021 21:43:40 C Hamilton <adenaculture at gmail.com>:
> >>> > If I use LIKE instead of ILIKE then it works. It is like ILIKE was
> not implemented for GeoPackage. Can anyone verify this?
> >>>
> >>> Yes, there seems to be no iLike in sqlite:
> >>>
> >>>
> https://stackoverflow.com/questions/15480319/case-sensitive-and-insensitive-like-in-sqlite
> >>>
> >>> And therefore neither in geopackage.
> >>>
> >>> Regards
> >>> Anita
> >>
> >> _______________________________________________
> >> QGIS-Developer mailing list
> >> QGIS-Developer at lists.osgeo.org
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >
> > _______________________________________________
> > QGIS-Developer mailing list
> > QGIS-Developer at lists.osgeo.org
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20210729/820d672c/attachment.html>