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<div>Hi to all</div>
<div><br/>
because I need polygons with a counterclockwise-orientation (and their holes in clockwise direction) I have dealt with the extension SFCGAL and ST_ForceLHR. A few questions have emerged ...<br/>
<br/>
1.</div>
<div>I have updated postgis to 2.2.0 and installed the PostGIS extension postgis_sfcgal. According to the documentation I can switch between sfcgal postgis.backend / postgis.backend geos. Why is it possible to run <em>sfcgal </em>functions even when I specify explicitly <em>geos </em>as backend? And which version of the mentioned function is then used (sfcgal, geos)? "<em>Some</em><em> SFCGAL functions replace standard ones (ST_Intersects, ST_Intersection, ST_Difference, ST_Union, ST_Area and ST_Distance)"</em><br/>
2.</div>
<div>Why is it not possible to use the functions ST_ForceLHR / ForceRHR on geography?<br/>
3.</div>
<div>Why is the orientation of the "holes" in polygons using ST_ForceRHR considered, but not when using ST_ForceLHR? --> Is there an easy way to change that or a workaround?<br/>
4.</div>
<div>Why does ST_ForceRHR work only with polygons and not as ST_ForceLHR also with multipolygons?</div>
<div> </div>
<div>The Version I am using:</div>
<div>PostgreSQL 9.3.5, compiled by Visual C++ build 1600, 64-bit on Windows</div>
<div>Postgis 2.2.0</div>
<div> </div>
<div>Biggest Problem of all:</div>
<div>If I use ST_ForceLHR with a bigger polygon or a multipolygon postgresql crashes and is not able to recover because of a “pre-existing shared memory block is still in use”</div>
<div><em>LOG: server process (PID 30468) was terminated by exception 0xC00000FD</em></div>
<div><em>DETAIL: Failed process was running: SELECT xy(4056532,12283) <-- Function including ST_ForceLHR </em></div>
<div><em>HINT: See C include file "ntstatus.h" for a description of the hexadecimal value.</em></div>
<div><em>LOG: terminating any other active server processes</em></div>
<div><em>…</em></div>
<div><em>postgres@Test FATAL: the database system is in recovery mode</em></div>
<div><em>LOG: all server processes terminated; reinitializing</em></div>
<div><em>FATAL: pre-existing shared memory block is still in use</em></div>
<div><em>HINT: Check if there are any old server processes still running, and terminate them.</em></div>
<div> </div>
<div>Any help will be great!!</div>
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