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<p>Hi all,</p>
<p>For reference I wrote about this here:
<a class="moz-txt-link-freetext" href="https://gis.stackexchange.com/a/212398">https://gis.stackexchange.com/a/212398</a></p>
<p>A small addition to Andreas' statement "filtering can only be
done on the client", this is no longer entirely the case, a lot of
standard SQL can already be translated and sent to the backend.</p>
It would be possible to adjust the "query builder" - also known as
subsetString - to also work with QgsExpressions.<br>
Pro: increased portability between providers and better "QGIS
standard" compatibility with things like support for variables and
python expression functions<br>
Con: less integration with what some providers (mostly databases)
offer natively (some advanced SQL)<br>
I think there is a need for both, so I could also imagine a radio
button to switch between the two.<br>
<br>
Matthias<br>
<br>
<div class="moz-cite-prefix">On 9/15/17 6:26 PM, Andreas Neumann
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:fe5b7fc5-f351-769c-86bf-b36a2cd57137@carto.net">
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<p>Hi Paolo,</p>
<p>I asked the same question, but apparently there are technical
reasons.</p>
<p>The Query builder creates a query that a data source can
understand (e.g. OGR) - data is filtered at its source.</p>
<p>Whereas the expression builder is much, much richer and can't
be translated to filters of data providers. Thus, such data
filtering can only be done in the client - means that all
features are requested from the source and then filtered client
side.</p>
<p>I don't know if it would be technically possible to restrict
the expression builder to a subset that a data provider can
understand - so that the user can have just one interface, both
with a limited set of operators and functions.<br>
</p>
<p>Andreas<br>
</p>
<br>
<div class="moz-cite-prefix">On 15.09.2017 18:03, Paolo Cavallini
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:28336d54-ddeb-4a8c-d265-9fafc7b6a2d9@faunalia.it">
<pre wrap="">Hi all,
the two dialogs are quite different, whereas they do essentialy the same
thing. Questions:
* is there a specific reason why the Query builder has not been updated,
or is it just the usual lack of time?
* is anyone planning to work on this?
Thanks.
</pre>
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