[postgis-users] St_makevalid issue

[Paul van der Linden]

>>
>> >You could capture the full output from a few runs and provide that (with
>> >geometry as WKB). That might allow seeing if the discrepancy is real and
>> >why it is happening.
>>
>
>In the sample output you provided, the geometry for Barisal is indeed
>invalid, but the isValid in the select list shows true.
>
>For the record, I tried the query on PostGIS 3/GEOS 3.8, and it worked as
>expected - no rows returned.
>
>If this is truly a Heisenbug [1], it's going to be very hard to debug, and
>even if tracked down, there's unlikely to be a simple fix.  The advice is
>almost always to upgrade, since upgrades contain numerous fixes (and in
>this case seem to definitely solve the problem).
>
>If it's impossible to upgrade, you'll have to figure out a workaround.
>Without knowing the use case it's impossible to recommend something.  I do
>note that you are pushing the limits of ST_SimplifyPreserveTopology, which
>seems like an odd thing to do.

Just installed latest postgres12 with latest postgis.
"POSTGIS="3.0.1 3.0.1" [EXTENSION] PGSQL="120" GEOS="3.8.0-CAPI-1.13.1 "
PROJ="Rel. 5.2.0, September 15th, 2018" LIBXML="2.9.9" LIBJSON="0.12"
LIBPROTOBUF="1.2.1" WAGYU="0.4.3 (Internal)""
"PostgreSQL 12.2, compiled by Visual C++ build 1914, 64-bit"
On windows 7 64bit.

Still having the same issues though not 100% of the time, more like 10%
And also giving "t" for ST_isvalid(simplifiedgeo2) despite the WHERE NOT
ST_isvalid(simplifiedgeo2)
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