https://issues.qgis.org/https://issues.qgis.org/favicon.ico2011-07-25T07:16:13ZQGIS Issue TrackingQGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=253272011-07-25T07:16:13ZPaolo Cavallinicavallini@faunalia.it
<ul><li><strong>Tracker</strong> changed from <i>Feature request</i> to <i>4</i></li><li><strong>Start date</strong> set to <i>2011-07-25</i></li><li><strong>Pull Request or Patch supplied</strong> set to <i>No</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=270622011-12-16T11:45:11ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Target version</strong> changed from <i>Version 1.7.0</i> to <i>Version 1.7.4</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=289882012-02-03T02:49:45ZPaolo Cavallinicavallini@faunalia.it
<ul><li><strong>Affected QGIS version</strong> set to <i>master</i></li><li><strong>Priority</strong> changed from <i>Low</i> to <i>Normal</i></li><li><strong>Crashes QGIS or corrupts data</strong> set to <i>No</i></li></ul><p>Confirmed in current master. Furthermore, the dbf table is mostly filled up with NULLs.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=289892012-02-03T03:49:25ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Category</strong> changed from <i>Python plugins</i> to <i>44</i></li><li><strong>Crashes QGIS or corrupts data</strong> changed from <i>No</i> to <i>Yes</i></li></ul><p>The issue applies also to other vector geoprocessing tools (both lack of speed and corrupted attributes) and to me (just my opinion) is a show stopper.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=289902012-02-03T03:50:52ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Subject</strong> changed from <i>dissolve tool very inefficient (with large datasets?)</i> to <i>dissolve tool very slow</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=302092012-04-15T07:23:02ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Tracker</strong> changed from <i>4</i> to <i>Bug report</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=307102012-04-16T02:16:51ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Operating System</strong> deleted (<del><i>All</i></del>)</li><li><strong>Priority</strong> changed from <i>Normal</i> to <i>High</i></li><li><strong>Status info</strong> deleted (<del><i>0</i></del>)</li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=309952012-04-16T04:28:03ZPaolo Cavallinicavallini@faunalia.it
<ul><li><strong>Target version</strong> changed from <i>Version 1.7.4</i> to <i>Version 1.8.0</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=322992012-05-30T01:34:06ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Assignee</strong> deleted (<del><i>cfarmer -</i></del>)</li></ul><p>Hi Salvatore and Alex, are you willingly/available to give this a look? You have done a so great job in the last days that would be great to have also this fixed in time for 1.8</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323382012-05-30T12:04:20ZSalvatore Larosalrssvtml@gmail.com
<ul></ul><p>I think is not possible before of upcoming 1.8!<br />Many fTools are slow with this heavy files!!</p>
<p>For me it is a target 2.0.0 version!</p>
<p>Waiting for feedback from Alexander et al.!</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323392012-05-30T12:09:49ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Salvatore Larosa wrote:</p>
<blockquote>
<p>I think is not possible before of upcoming 1.8!<br />Many fTools are slow with this heavy files!!</p>
<p>For me it is a target 2.0.0 version!</p>
<p>Waiting for feedback from Alexander et al.!</p>
</blockquote>
<p>too bad... because it is just not slow... it freezes qgis... thanks anyway!</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323452012-05-30T21:54:26ZAlexander Bruy
<ul></ul><p>Seems test dataset not available anymore. Is it possible to upload it again?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323462012-05-30T21:59:12ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Alexander Bruy wrote:</p>
<blockquote>
<p>Seems test dataset not available anymore. Is it possible to upload it again?</p>
</blockquote>
<p>Hi Alexander, the link in the description works for me. Does not for you?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323482012-05-30T22:07:58ZAlexander Bruy
<ul></ul><p>Giovanni Manghi wrote:</p>
<blockquote>
<p>Hi Alexander, the link in the description works for me. Does not for you?</p>
</blockquote>
<p>Giovanni, it doesn't works for me.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=323552012-05-30T22:33:34ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Alexander Bruy wrote:</p>
<blockquote>
<p>Giovanni, it doesn't works for me.</p>
</blockquote>
<p>try here</p>
<p><a class="external" href="http://ubuntuone.com/3Je6Dqp082xBERVWalE48U">http://ubuntuone.com/3Je6Dqp082xBERVWalE48U</a></p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=338302012-08-13T08:34:12ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Giovanni Manghi wrote:</p>
<blockquote>
<p>Alexander Bruy wrote:</p>
<blockquote>
<p>Giovanni, it doesn't works for me.</p>
</blockquote>
<p>try here</p>
<p><a class="external" href="http://ubuntuone.com/3Je6Dqp082xBERVWalE48U">http://ubuntuone.com/3Je6Dqp082xBERVWalE48U</a></p>
</blockquote>
<p>seems still very slow, even with this patch</p>
<p><a class="external" href="https://github.com/qgis/Quantum-GIS/pull/175">https://github.com/qgis/Quantum-GIS/pull/175</a></p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=338322012-08-13T08:39:53ZAlexander Bruy
<ul></ul><p>Giovanni Manghi wrote:</p>
<blockquote>
<p>seems still very slow, even with this patch</p>
<p><a class="external" href="https://github.com/qgis/Quantum-GIS/pull/175">https://github.com/qgis/Quantum-GIS/pull/175</a></p>
</blockquote>
<p>This patch is for very specific use case (when geometries are simply, but there are many unique values in attributes used for dissolve) and useless for usual usage</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=346222012-09-04T10:01:13ZPaolo Cavallinicavallini@faunalia.it
<ul><li><strong>Target version</strong> changed from <i>Version 1.8.0</i> to <i>Version 2.0.0</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=380562012-12-30T09:22:55ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>see also <a class="issue tracker-1 status-5 priority-4 priority- closed" href="https://issues.qgis.org/issues/5779" title="Error when executing Dissolve (Closed)">#5779</a></p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=415182013-05-31T06:46:37ZSandro Santillistrk@kbt.io
<ul></ul><p>Is this still an issue ? Is it correct for this to be marked as "causes crash or corruption"?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=415202013-05-31T06:48:29ZJürgen Fischerjef@norbit.de
<ul><li><strong>Crashes QGIS or corrupts data</strong> changed from <i>Yes</i> to <i>No</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=415222013-05-31T07:15:54ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Sandro Santilli wrote:</p>
<blockquote>
<p>Is this still an issue ? Is it correct for this to be marked as "causes crash or corruption"?</p>
</blockquote>
<p>yes, for even not very large vectors it is basically unusable.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=415232013-05-31T07:16:56ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Sandro Santilli wrote:</p>
<blockquote>
<p>Is this still an issue ? Is it correct for this to be marked as "causes crash or corruption"?</p>
</blockquote>
<p>don't know why it was removed the "causes crash" flag, because this tool have the tendency to freeze the program.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438312013-08-06T10:30:18ZPieter Roggemanspieter.roggemans@gmail.com
<ul></ul><p>Indeed very slow :-(.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438322013-08-06T10:32:42ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Pieter Roggemans wrote:</p>
<blockquote>
<p>Indeed very slow :-(.</p>
</blockquote>
<p>in qgis 2.0, with SEXTANTE, you have (fast) alternatives, both SAGA and GRASS have dissolve tools.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438332013-08-06T11:00:21ZPieter Roggemanspieter.roggemans@gmail.com
<ul></ul><p>Yep, I saw and tried both, but they both gave the same type of error using the most recent qgis 1.9 (see below for the error).</p>
<p>I did the dissolve in ArcView now, so I'm fine, but just wanted to reconfirm the problem... should have mentioned that I already had a workaround.</p>
<p>Thanks anyway!</p>
<blockquote>
<p>Oooops! SEXTANTE could not open the following output layers</p>
<p>Dissolved Polygons: C:\\Users\\Pieter\\AppData\\Local\\Temp\\sextante\\sagapolygondissolveallpolygonsac891687dc4e4bb89b8dc28e72b0cb16.shp<br />The above files could not be opened, which probably indicates that they were not correctly produced by the executed algorithm</p>
<p>Checking the log information might help you see why those layers were not created as expected</p>
<p>This algorithm requires SAGA to be run. A test to check if SAGA is correctly installed and configured in your system has been performed, with the following result:</p>
<p>SAGA seems to be correctly installed and configured</p>
</blockquote> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438452013-08-07T00:45:39ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Pieter Roggemans wrote:</p>
<blockquote>
<p>Yep, I saw and tried both, but they both gave the same type of error using the most recent qgis 1.9 (see below for the error).</p>
<p>I did the dissolve in ArcView now, so I'm fine, but just wanted to reconfirm the problem... should have mentioned that I already had a workaround.</p>
<p>Thanks anyway!</p>
</blockquote>
<p>did you correctly configured SAGA in SEXTANTE options? in QGIS master you must use SAGA 2.1 then dissolve will run. I just tested.</p>
<p>Unfortunately it seems that polygon dissolve in SAGA 2.1 is bugged (it works ok in SAGA 2.0.8), but anyway the good news you can always use v.dissolve from GRASS.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438532013-08-07T12:18:10ZPieter Roggemanspieter.roggemans@gmail.com
<ul></ul><p>I simply installed the qgis dev version from OSGeo4W, I didn't do anything to the configuration. I only found a saga 2.0.8 that is installed in the OSGeo4W dir, so I suppose that will be the version used by GGis?</p>
<p>Anyway... Grass gives exactly the same error as the one quoted in my previous post, only SAGA is replaced by GRASS...</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=438852013-08-08T01:19:47ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Pieter Roggemans wrote:</p>
<blockquote>
<p>I simply installed the qgis dev version from OSGeo4W, I didn't do anything to the configuration. I only found a saga 2.0.8 that is installed in the OSGeo4W dir, so I suppose that will be the version used by GGis?</p>
<p>Anyway... Grass gives exactly the same error as the one quoted in my previous post, only SAGA is replaced by GRASS...</p>
</blockquote>
<p>in osgeo4w there is still saga 2.0.8 but you can manually download 2.1 and configure sextante to use it. GRASS also probably does not work because of a recent update in osgeo4w, but again in sextante configurations you can fix and then they both will work.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=480232014-01-30T22:43:38ZPaolo Cavallinicavallini@faunalia.it
<ul><li><strong>Target version</strong> changed from <i>Version 2.0.0</i> to <i>Future Release - High Priority</i></li></ul> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=482212014-02-07T04:25:28ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Priority</strong> changed from <i>High</i> to <i>Normal</i></li></ul><p>There is no crash or data corruption, so I'm lowering the priority also because there are alternatives in the processing toolbox.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=525582014-06-20T13:03:04ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Status</strong> changed from <i>Open</i> to <i>Closed</i></li><li><strong>Resolution</strong> set to <i>wontfix</i></li></ul><p>I'm closing this because the alternatives in the processing toolbox are good enough and also because no one seems to have interest in making better the native qgis tool.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=789232017-04-30T23:22:11ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>The "ftools" category is being removed from the tracker, changing the category of this ticket to "Processing/QGIS" to not leave the category orphaned.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=809982017-07-19T15:19:26ZMike Bannistermikebannis@gmail.com
<ul></ul><p>Giovanni Manghi wrote:</p>
<blockquote>
<p>I'm closing this because the alternatives in the processing toolbox are good enough and also because no one seems to have interest in making better the native qgis tool.</p>
</blockquote>
<p>I just ran into this issue with a relatively small dataset (9MB). VERY slow run time and appeared to corrupt the data. If the tool doesn't work should it be removed or have a pop up dialog that directs the user to the other options?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=809992017-07-19T15:21:48ZGiovanni Manghigiovanni.manghi@gmail.com
<ul><li><strong>Regression?</strong> set to <i>No</i></li><li><strong>Description</strong> updated (<a href="/journals/diff/80999?detail_id=69822" title="View differences">diff</a>)</li><li><strong>Easy fix?</strong> set to <i>No</i></li></ul><p>Mike Bannister wrote:</p>
<blockquote>
<p>Giovanni Manghi wrote:</p>
<blockquote>
<p>I'm closing this because the alternatives in the processing toolbox are good enough and also because no one seems to have interest in making better the native qgis tool.</p>
</blockquote>
<p>I just ran into this issue with a relatively small dataset (9MB). VERY slow run time and appeared to corrupt the data. If the tool doesn't work should it be removed or have a pop up dialog that directs the user to the other options?</p>
</blockquote>
<p>yes use the GDAL based one. In QGIS3 the native QGIS tool will be much improved.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810102017-07-19T20:14:21ZNyall Dawson
<ul></ul><p>Mike - which qgis version are you using? Can you attach your data?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810352017-07-20T11:50:03ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Nyall Dawson wrote:</p>
<blockquote>
<p>Mike - which qgis version are you using?</p>
</blockquote>
<p>Nyall, beside master it doesn't really matter when speaking about the native QGIS tool. It has <strong>always</strong> been dead slow since its ftools times especially when dealing with large/complex input layers (and sometimes even not so large/complex).</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810622017-07-20T22:32:46ZNyall Dawson
<ul></ul><p>Giovanni - have you tested since <a class="changeset" href="https://issues.qgis.org/projects/qgis/repository/revisions/ae59b733c3473f375d80a3680e44a98ab4586bd7" title="[processing] Use unary union in dissolve (much faster for many complex geometry inputs)">ae59b733c3473f375d80a3680e44a98ab4586bd7</a> (i.e. 2.18)?</p>
<p>If it's still slow/unstable, give me test data and I'll fix! I need DATA though! DATA!!!11!! maw data!!!1!! I NEED IT!!11!!1.1.1.1.1.1</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810632017-07-20T22:34:09ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Nyall Dawson wrote:</p>
<blockquote>
<p>Giovanni - have you tested since <a class="changeset" href="https://issues.qgis.org/projects/qgis/repository/revisions/ae59b733c3473f375d80a3680e44a98ab4586bd7" title="[processing] Use unary union in dissolve (much faster for many complex geometry inputs)">ae59b733c3473f375d80a3680e44a98ab4586bd7</a> (i.e. 2.18)?</p>
<p>If it's still slow/unstable, give me test data and I'll fix! I need DATA though! DATA!!!11!! maw data!!!1!! I NEED IT!!11!!1.1.1.1.1.1</p>
</blockquote>
<p>I will get you data ;) as well as for intersections, unions, differences et al.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810722017-07-21T09:05:37ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Nyall Dawson wrote:</p>
<blockquote>
<p>Giovanni - have you tested since <a class="changeset" href="https://issues.qgis.org/projects/qgis/repository/revisions/ae59b733c3473f375d80a3680e44a98ab4586bd7" title="[processing] Use unary union in dissolve (much faster for many complex geometry inputs)">ae59b733c3473f375d80a3680e44a98ab4586bd7</a> (i.e. 2.18)?</p>
<p>If it's still slow/unstable, give me test data and I'll fix! I need DATA though! DATA!!!11!! maw data!!!1!! I NEED IT!!11!!1.1.1.1.1.1</p>
</blockquote>
<p>see below shapefile, dissolve it by "distrito". On 2.18.10-nightly it takes minutes with the QGIS native tools, seconds with the GDAL one. On QGIS3 the native tool is as much as fast as the GDAL one.</p>
<p><a class="external" href="https://www.dropbox.com/s/a3jl5z4a2z47jg8/conc.zip?dl=0">https://www.dropbox.com/s/a3jl5z4a2z47jg8/conc.zip?dl=0</a></p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=810762017-07-21T09:32:58ZRegis Haubourgregis.haubourg@oslandia.com
<ul></ul><p>Talking about dissolve tool, we have been working in the last months to fix an issue with unaryUnion raised topology exception and returning NULL geometry output in QGIS or PostGIS. <br />Next 3.6.2 is currently being released and moving qgis packages to GEOS 3.6.2 would be a good move, there a many bugfixes already in there useful for processing. Many thanks to Sandro Santilli for that work.</p>
<p>When consolidating queries to finally isolate the bug, I had to apply many optimizations only documented in GEOS source code or stackExchange (or again ESRI doc !) , such as dumping all multigeometries to single geometries before running ST_UnaryUnion, then collecting them, checking for validaty or adding a snaptogrid step for precision issues.</p>
<p>[[<a class="external" href="https://geos.osgeo.org/doxygen/classgeos_1_1operation_1_1geounion_1_1UnaryUnionOp.html">https://geos.osgeo.org/doxygen/classgeos_1_1operation_1_1geounion_1_1UnaryUnionOp.html</a><br />]]<br />[[<a class="external" href="https://gis.stackexchange.com/questions/204370/significant-performance-issues-with-postgis-unaryunion/204443">https://gis.stackexchange.com/questions/204370/significant-performance-issues-with-postgis-unaryunion/204443</a>]]</p>
<pre>
</pre>
<p>The check validity part is already in master, IIRC.<br />I think this is worth porting this logic to the default algorithm in QGIS. <br />See the equivalent PostGIS request that revealed a lot more robust than the raw Union operator:</p>
<pre>
select "tableA", "codeTableA",
st_area(ST_UnaryUnion(st_collect(geom_intersection))) geomdissolvedarea, --Unary
st_area(ST_UnaryUnion(st_collect(geom_intersection))) / "areaObjectA" as ratio_couv
FROM
(
Select
'public.communes'::character varying "tableA",
a.code::character varying "codeTableA",
b.code::character varying "codeTableB",
'public.couv4g'::character varying "tableB",
st_intersection(st_snaptogrid(a.geom, 0.0001) , st_snaptogrid( ( CASE WHEN st_isvalid(b.geom) then b.geom ELSE st_makevalid(b.geom) END ), 0.0001)) as geom_intersection, -- snaptogrid to avoid some precision issues
FROM
-- >>>>> dump all objects in tableA >>>
( select code_com::character varying code, (st_dump(geom)).geom geom from public.communes ) a
JOIN
( -- >>>>> dump all objects in tableB >>>
select code_bds as code, st_dump(geom) from public.couv4g
) b
ON (st_intersects(a.geom, b.geom)) -- spatial relation and index clause
) as crosselem
GROUP BY "tableA", "codeTableA", "areaObjectA"
</pre>
<p>Any opinion on that? Nyall, could you ping us when your work is finished in that area?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=811252017-07-22T01:57:26ZNyall Dawson
<ul></ul><p>Can we open a GitHub page or something to collect these findings together? I'm having trouble keeping on top of the current state of these fubdamental algorithm related issues/improvements.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=811292017-07-22T11:33:52ZGiovanni Manghigiovanni.manghi@gmail.com
<ul></ul><p>Nyall Dawson wrote:</p>
<blockquote>
<p>Can we open a GitHub page or something to collect these findings together? I'm having trouble keeping on top of the current state of these fubdamental algorithm related issues/improvements.</p>
</blockquote>
<p>yes Nyall, agree. I don't have permissions to create the page on GH QGIS account, probably you do. Once setup I will add sample data for QGIS native geoprocessing tools to show slowness, incorrect results and other issues.</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=811412017-07-23T02:00:49ZNyall Dawson
<ul></ul><p>How about <a class="external" href="https://github.com/nyalldawson/QGIS/wiki/Processing-Algorithm-Bugs-and-Enhancements">https://github.com/nyalldawson/QGIS/wiki/Processing-Algorithm-Bugs-and-Enhancements</a> ?</p> QGIS Application - Bug report #3828: dissolve tool very slowhttps://issues.qgis.org/issues/3828?journal_id=811542017-07-24T08:22:25ZRegis Haubourgregis.haubourg@oslandia.com
<ul></ul><p>Giovanni Manghi wrote:</p>
<blockquote>
<p>Nyall Dawson wrote:</p>
<blockquote>
<p>Can we open a GitHub page or something to collect these findings together? I'm having trouble keeping on top of the current state of these fubdamental algorithm related issues/improvements.</p>
</blockquote></blockquote>
<p>I added my tips there! thanks Nyall!</p>