[mapserver-users] Highly inefficient MakeValid statement in Mapserver-generated spatial queries

[Istvan Keszei]

We have real large geospatial tables.  Not having an option to turn MakeValid off will kill our applications’ performance as indexes are essential. 

For a simple query, the disk reads are 100x more for a query including the MakeValid. Hence, the cpu resources required are multifold too.

Yes, please turn it off or make it optional. Can this be done manually somehow? We have waited long months for 4.0.1 to come out (with the opacity fix) and now this issue prevents the upgrade. 

I see the invalid geometries more of a data maintenance responsibility rather than a query-side-responsibility. I understand for some people this is convenient, so that is why I suggest to make this optional. 

Any help is appreciated!

Thank you,
Istvan


> On 2019. Sep 7., at 23:55, Tamas Szekeres <szekerest at gmail.com> wrote:
> 
> I think we can remove MakeValid from the queries entirely. 
> The problem is that if the table contains invalid geometries, the entire query will fail.
> 
> Best regards,
> 
> Tamas
> 
> 
> Seth G <sethg at geographika.co.uk> ezt írta (időpont: 2019. szept. 7., Szo, 21:35):
>> Hi,
>> 
>> Good question. This is a fairly new change as part of https://github.com/mapserver/mapserver/issues/5781 from April this year. 
>> In SQL Profiler I seem to get GEOM.STIntersects for WFS requests and GEOM.MakeVaid().STIntersects for WMS. 
>> MakeValid does appear to stop the index being used. Do you have a link which says this definitively?
>> 
>> Seth
>> 
>> --
>> web:http://geographika.co.uk
>> twitter: @geographika
>> 
>> 
>>> On Sat, Sep 7, 2019, at 12:02 PM, ikeszei at yahoo.com wrote:
>>> Hello,
>>> 
>>>  
>>> 
>>> I noticed that when MapServer issues the query to MS SQL Server, it appends a .MakeValid() tag to the geometry field, which makes data access highly inefficient as no spatial indexes can be used when the MakeValid() is used. Here is the query that is being produced:
>>> 
>>>  
>>> 
>>> SELECT
>>> 
>>> convert(nvarchar(max), [label]),
>>> 
>>> [ogr_geometry],
>>> 
>>> convert(varchar(36), [ogr_fid])
>>> 
>>> FROM
>>> 
>>> section
>>> 
>>> WHERE
>>> 
>>> ogr_geometry.MakeValid().STIntersects(geometry::STGeomFromText('POLYGON((-10973271.1167343 5605636.0681215,-10963019.0003155 5605636.0681215,-10963019.0003155 5614459.76757417,-10973271.1167343 5614459.76757417,-10973271.1167343 5605636.0681215))',3857)) = 1
>>> 
>>>  
>>> 
>>> Here is the data access string from the map file:
>>> 
>>>  
>>> 
>>> DATA "ogr_geometry from section USING UNIQUE ogr_fid USING SRID=3857"
>>> 
>>>  
>>> 
>>> Earlier I was using a specific HINT for index usage:
>>> 
>>>  
>>> 
>>> DATA "ogr_geometry from section WITH (INDEX(section_ogr_geometry_idx)) USING UNIQUE ogr_fid USING SRID=3857"
>>> 
>>>  
>>> 
>>> But since MapServer adds the MakeValid automatically, I am getting the following error:
>>> 
>>>  
>>> 
>>> Msg 8635, Level 16, State 9, Line 1
>>> 
>>> The query processor could not produce a query plan for a query with a spatial index hint.  Reason: Could not find required binary spatial method in a condition.  Try removing the index hints or removing SET FORCEPLAN.
>>> 
>>>  
>>> 
>>> How do I configure mapserver to NOT ADD the MakeValid to every single one of its queries ?
>>> 
>>>  
>>> 
>>> Any response is much appreciated !
>>> 
>>>  
>>> 
>>> Thanks,
>>> 
>>> Istvan
>>> 
>>>  
>>> 
>>>  
>>> 
>>> _______________________________________________
>>> mapserver-users mailing list
>>> mapserver-users at lists.osgeo.org
>>> https://lists.osgeo.org/mailman/listinfo/mapserver-users
>> 
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