[postgis-devel] Major bug with postgis && operator, affecting topology

[Rémi Cura]

Paul committed a (supposed) fix.
I updated my postgis,
and will use this new version to see if the bug happens again.
Many thanks for the super-fast fix !
Cheers,
Rémi-C

2015-06-01 16:18 GMT+02:00 Rémi Cura <remi.cura at gmail.com>:

> Data in the ticket.
> I dropped the topology and recreated it, no more issues.
> Note that I was able to do it because it was a toy database,
> I would have been stuck if seriously using it.
>
> Maybe it has something to do with lot of transaction cancelling (when I
> debug, I raise a lot of exceptions ).
>
> As for the safeguard,
> it is necessary not safe.
>
> I'm not an expert, so it's just a guess.
> Maybe you have to consider
>
>     `Nan > 1` ==> always false , so not safe (your safeguard wouldn't be
> executed)
>
> It could be because `ntuples_max` is 0 or NaN.
> Then you have `selectivity = val / ntuples_max;`
> In my case there is no row to return anyway.
>
> Maybe you should put selectivity to `0.5` if NaN or Infinity?
>
>
> Cheers,
> Rémi-C
>
> 2015-06-01 15:52 GMT+02:00 Paul Ramsey <pramsey at cleverelephant.ca>:
>
>> Because by inspection, I don't see how anything gets past this:
>>
>>
>> https://github.com/postgis/postgis/blob/svn-trunk/postgis/gserialized_estimate.c#L1094-L1096
>>
>> On Mon, Jun 1, 2015 at 6:49 AM, Paul Ramsey <pramsey at cleverelephant.ca>
>> wrote:
>> > Reproduction data?
>> > P
>> >
>> >
>> > --
>> > http://postgis.net
>> > http://cleverelephant.ca
>> >
>> >
>> > On June 1, 2015 at 6:47:27 AM, Rémi Cura (remi.cura at gmail.com) wrote:
>> >> Hey,
>> >> I re-opened the ticket [here](
>> >> http://trac.osgeo.org/postgis/ticket/2543#comment:21).
>> >>
>> >> This is a major bug (in my opinion).
>> >>
>> >>
>> >> Simply doing something like
>> >> ------
>> >> SELECT *
>> >> FROM node, face
>> >> WHERE geom && mbr
>> >> --------
>> >>
>> >> raises an error
>> >> "ERROR: invalid join selectivity:"
>> >> (answer should be None, tables have one line each! )
>> >>
>> >> This is pretty terrible, because spatial intersect is at the basis of
>> >> PostGIS, and it affects classical PostGIS topology tables, so it is not
>> >> possible to change the tables easily.
>> >>
>> >> Worse, it affects a pretty recent PostGIS version (POSTGIS="2.2.0dev
>> >> r12846" GEOS="3.5.0dev-CAPI-1.9.0 r0" PROJ="Rel. 4.8.0, 6 March 2012"
>> >> GDAL="GDAL 2.0.0dev, released 2014/04/16" LIBXML="2.8.0" TOPOLOGY
>> RASTER),
>> >> with Postgres 9.3 and Ubuntu 12.04.
>> >>
>> >> Cheers,
>> >> Remi-C
>> >> _______________________________________________
>> >> postgis-devel mailing list
>> >> postgis-devel at lists.osgeo.org
>> >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-devel
>> >
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-devel/attachments/20150602/78288947/attachment.html>