[mapserver-dev] Support for feature querying without spatial filtering

[Tamas Szekeres]

Steve,

I was thinking about this also. But with some coordinate systems (-1,-1,-1,-1)
may specify a valid point location (which can eventually be used as the
spatial filter).
But thinking this further, the drivers may test whether the specified
rectangle is equal with (or contains entirely) the spatial extent of the
layer and omit including the spatfilter in the query statement in such
cases. I'll see how this can work with mssql2008.

Best regards,

Tamas





2012/9/17 Lime, Steve D (DNR) <Steve.Lime at state.mn.us>

>  Another idea I wondered about is if we could simply use a certain
> degenerate rectangle (-1,-1,-1,-1) or something like that to trigger this
> behavior. That would require no modification of the main
> msLayerWhichShapes() function. Drivers would have to be tweaked. One
> benefit is that users could trigger this via CGI too.  --Steve
>
>  ------------------------------
> *From:* mapserver-dev-bounces at lists.osgeo.org [
> mapserver-dev-bounces at lists.osgeo.org] on behalf of Tamas Szekeres [
> szekerest at gmail.com]
> *Sent:* Sunday, September 16, 2012 3:55 PM
> *To:* mapserver-dev at lists.osgeo.org
> *Subject:* [mapserver-dev] Support for feature querying without spatial
> filtering
>
>  Hi Devs,
>
>  I'd like to establish support for querying the shapes without a spatial
> filter. The query would be initiated from the mapscript interface, but I
> would prefer to notify the driver not to use the spatial filter in some
> cases.
>
>  The most compelling reasons to implement such change are:
>
>  1. When using an attribute query or a filter expression query, we don't
> know or don't want to specify a search rectangle.
> 2. We can experience a performance increment (especially for the database
> drivers) by reducing the complexity of the query execution plan.
>
>  The most straightforward implementation would be to modify the
> parameters of whichShapes from:
>
>  int msLayerWhichShapes(layerObj *layer, rectObj rect, int isQuery)
>
>  to:
>
>  int msLayerWhichShapes(layerObj *layer, rectObj rect, int options)
>
>  we could use constant values for options such as:
>
>  #define MS_QUERYOPT_ISQUERY  0x01
> #define MS_QUERYOPT_NONSPATIAL  0x02
>
>  Drivers should take care of using MS_QUERYOPT_NONSPATIAL. In the first
> turn, I'd like to implement using this for mssql2008 specifically.
>
>  Let me know what you think.
>
>
>  Best regards,
>
>  Tamas
>
>
>
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