<div dir="ltr">Hi Jukka,<div><br></div><div>Thanks for all the dialect info.</div><div><br></div><div>Reading your last message about testing the dialect in use, I have to admit that I did not think about native sql</div><div>(dialect) being deduced from the source type rather than from any dbms involved.</div><div>That is clear to me now, of course.</div><div><br></div><div>Would it be correct, then, that, when using SQL when converting from shapefile to postgresql/postgis,</div><div>dialect sqlite (or ogr_sql) cannot be avoided? I can live with that, of course. Perhaps I'll start converting my</div><div>'special' geometry functions to dll's in postgresql so that I don't need to convert and reconvert to/from shapefile.</div><div><br></div><div>Specifically I am working on what in arcgis is called union, which divides overlapping polygons in constituent</div><div>parts without overlaps. This function does not seem present in postgis and is problematic anyway when</div><div>the dataset is large enough.</div><div>(The Dutch spatial planning dataset 'Enkelbestemming' is such a dataset with over 2.6 million entries with</div><div>overlaps both small and large, but to me, at least in terms of efficient data access, the very essence of the idea</div><div>is that you have at most one valid geometry with attributes for each (point)location.)</div><div><br></div><div>Best regards and thanks,</div><div>Jan</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jun 9, 2022 at 12:19 PM Rahkonen Jukka <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi">jukka.rahkonen@maanmittauslaitos.fi</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span>Hi,<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">You are getting closer but at the bottom of the page
<a href="https://gdal.org/user/ogr_sql_dialect.html" target="_blank">https://gdal.org/user/ogr_sql_dialect.html</a> there is an important paragraph:<br>
<br>
Non-OGR SQL<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">All OGR drivers for database systems: MySQL, PostgreSQL / PostGIS, Oracle Spatial, SQLite / Spatialite RDBMS, ODBC RDBMS, ESRI Personal GeoDatabase, SAP HANA and MSSQLSpatial - Microsoft
SQL Server Spatial Database, override the GDALDataset::ExecuteSQL() function with dedicated implementation and, by default, pass the SQL statements directly to the underlying RDBMS. In these cases the SQL syntax varies in some particulars from OGR SQL. Also,
anything possible in SQL can then be accomplished for these particular databases. Only the result of SQL WHERE statements will be returned as layers.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">So if you do not select SQL dialect for PostGIS you do not use the OGR SQL dialect but the native PostgreSQL one. For using OGR SQL with PostgreSQL (maybe it could make sense in some
special case but I am not sure) use “-dialect OGRSQL”. If you are uncertain about what dialect is in use you can make a tests with some native-only functions like -sql "select postgis_version()" or -sql “select sqlite_version”.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">-Jukka Rahkonen-<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b>Lähettäjä:</b> Andreas Oxenstierna <<a href="mailto:andreas.oxenstierna@t-kartor.com" target="_blank">andreas.oxenstierna@t-kartor.com</a>>
<br>
<b>Lähetetty:</b> torstai 9. kesäkuuta 2022 12.48<br>
<b>Vastaanottaja:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a>; Rahkonen Jukka <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>><br>
<b>Aihe:</b> Re: ogrinfo UPDATE performance request<u></u><u></u></p>
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<p class="MsoNormal">Hi<br>
<br>
Thanks a lot and sorry for the noise. <br>
UPDATE do work as expected using the OGR SQL, i.e. one atomic db transaction executing in the database = vastly faster than using -dialect sqlite<br>
.<br>
The doc at <a href="https://eur06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgdal.org%2Fuser%2Fogr_sql_dialect.html&data=05%7C01%7Cjukka.rahkonen%40maanmittauslaitos.fi%7C40cc50d74e814135428b08da49fd17a3%7Cc4f8a63255804a1c92371d5a571b71fa%7C0%7C0%7C637903648638713449%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=X63CofyOIyNwpeP%2Ba605L5ZCCn7Z8qP36rt5VwQc8eE%3D&reserved=0" target="_blank">https://gdal.org/user/ogr_sql_dialect.html</a> needs
some addition - I assume that INSERT, DELETE etc. also works<br>
"While in theory any sort of command could be handled this way, in practice the mechanism is used to provide a subset of SQL SELECT capability to applications."<br>
<br>
Maybe also clarify if the sqlite dialect is necessary to keep at all ...<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Best Regards<br>
<br>
Andreas Oxenstierna<br>
T-Kartor Geospatial AB<br>
Olof Mohlins väg 12 Kristianstad<br>
mobile: +46 733 206831<br>
mailto: <a href="mailto:andreas.oxenstierna@t-kartor.com" target="_blank">andreas.oxenstierna@t-kartor.com</a><br>
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<p class="MsoNormal">On 9 Jun 2022, 11:15 +0200, Rahkonen Jukka <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>>, wrote:<br>
<br>
<u></u><u></u></p>
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<p class="MsoNormal"><span>Hi,</span><u></u><u></u></p>
<p class="MsoNormal"><span> </span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US">This updated 166000 rows in 15 seconds for me on my laptop without any workarounds:</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US">ogrinfo PG:"host=localhost port=5432 dbname=my_pg user=user password=pw" -sql "update buildingtest set version=99"</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US"> </span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US">-Jukka Rahkonen-</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US"> </span><u></u><u></u></p>
<div>
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<p class="MsoNormal"><b>Lähettäjä:</b> Andreas Oxenstierna <<a href="mailto:andreas.oxenstierna@t-kartor.com" target="_blank">andreas.oxenstierna@t-kartor.com</a>><br>
<b>Lähetetty:</b> torstai 9. kesäkuuta 2022 12.02<br>
<b>Vastaanottaja:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a>; Rahkonen Jukka <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>><br>
<b>Aihe:</b> Re: ogrinfo UPDATE performance request<u></u><u></u></p>
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<p class="MsoNormal">Hi<br>
<br>
AFAIK, UPDATE only works with ogrinfo and the sqlite dialect. We have not tested the native PG SQL dialect extensively though, it took some time to find the correct syntax. <br>
And to answer one other mail, the table name needs to be written as \”<schema>.<table>\”, at least on macOS<br>
<br>
The performance issue is mainly that ogrinfo updates one feature at a time. Even if it should pack all data, copy it into a temp SQLite, do the update and transact back, it would be vastly faster if it is done in one transaction instead of one transaction for
each feature as it is done now.<br>
<br>
However, I realised that a workaround may be to add needed attribute info to any file format (GeoPackage or shape) - need to verify the performance though.<br>
It should be nice to be able to execute this in a pure GDAL/OGR environment - the use case is to aggregate on different values, resolutions and interpolation methods for an AI platform so we may need to test thousands of variants.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">Best Regards<br>
<br>
Andreas Oxenstierna<br>
T-Kartor Geospatial AB<br>
Olof Mohlins väg 12 Kristianstad<br>
mobile: +46 733 206831<br>
mailto: <a href="mailto:andreas.oxenstierna@t-kartor.com" target="_blank">andreas.oxenstierna@t-kartor.com</a><br>
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<p class="MsoNormal" style="margin-bottom:12pt">On 9 Jun 2022, 09:46 +0200, Rahkonen Jukka <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>>, wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span>Hi,</span><u></u><u></u></p>
<p class="MsoNormal"><span> </span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US">Do not use “-dialect sqlite” if you play with PostgreSQL but let GDAL to use the native PG SQL dialect.</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US"> </span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US">-Jukka Rahkonen-</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="EN-US"> </span><u></u><u></u></p>
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<div style="border-right:none;border-bottom:none;border-left:none;border-top:1pt solid rgb(225,225,225);padding:3pt 0cm 0cm">
<p class="MsoNormal"><b>Lähettäjä:</b> gdal-dev <<a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>>
<b>Puolesta</b> Andreas Oxenstierna<br>
<b>Lähetetty:</b> torstai 9. kesäkuuta 2022 9.50<br>
<b>Vastaanottaja:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br>
<b>Aihe:</b> [gdal-dev] ogrinfo UPDATE performance request<u></u><u></u></p>
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<p class="MsoNormal">Dear developers<br>
<br>
Ogr SQL update capabilities are really impressing but there is one major performance issue with update of many features, exemplified by:<br>
ogrinfo -dialect sqlite -sql "UPDATE <table> SET x = 1" PG:”<connection>"<br>
<br>
This is painfully slow because ogr updates features one by one and furthermore updates all existing attributes incl. geometries.<br>
Eg. updating 10000 features in pgAdmin/psql with UPDATE <table> SET x = 1 executes in milliseconds but takes several minutes with ogr.<br>
<br>
The current ogr functionality is also not correct from a database transactional point of view.<br>
<br>
I found an old RFC, <a href="https://eur06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgdal.org%2Fdevelopment%2Frfc%2Frfc13_createfeatures.html&data=05%7C01%7Cjukka.rahkonen%40maanmittauslaitos.fi%7C40cc50d74e814135428b08da49fd17a3%7Cc4f8a63255804a1c92371d5a571b71fa%7C0%7C0%7C637903648638869695%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=kt57EZEaekVUQ3o1yZSAHv0pMtSQMV50HIhGKSEdues%3D&reserved=0" target="_blank">
https://gdal.org/development/rfc/rfc13_createfeatures.html</a>, requesting this but it was withdrawn for reasons not anymore digitally available.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">Best Regards<br>
<br>
Andreas Oxenstierna<br>
T-Kartor Geospatial AB<br>
Olof Mohlins väg 12 Kristianstad<br>
mobile: +46 733 206831<br>
mailto: <a href="mailto:andreas.oxenstierna@t-kartor.com" target="_blank">andreas.oxenstierna@t-kartor.com</a><br>
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