[gdal-dev] ogrinfo UPDATE performance request

Thu Jun 9 03:18:45 PDT 2022

Hi,

You are getting closer but at the bottom of the page https://gdal.org/user/ogr_sql_dialect.html there is an important paragraph:

Non-OGR SQL
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.

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".

-Jukka Rahkonen-

Lähettäjä: Andreas Oxenstierna <andreas.oxenstierna at t-kartor.com>
Lähetetty: torstai 9. kesäkuuta 2022 12.48
Vastaanottaja: gdal-dev at lists.osgeo.org; Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi>
Aihe: Re: ogrinfo UPDATE performance request

Hi

Thanks a lot and sorry for the noise.
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
.
The doc at https://gdal.org/user/ogr_sql_dialect.html<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> needs some addition - I assume that INSERT, DELETE etc. also works
"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."

Maybe also clarify if the sqlite dialect is necessary to keep at all ...

Best Regards

Andreas Oxenstierna
T-Kartor Geospatial AB
Olof Mohlins väg 12 Kristianstad
mobile: +46 733 206831
mailto: andreas.oxenstierna at t-kartor.com<mailto:andreas.oxenstierna at t-kartor.com>
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On 9 Jun 2022, 11:15 +0200, Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>>, wrote:

Hi,

This updated 166000 rows in 15 seconds for me on my laptop without any workarounds:
ogrinfo PG:"host=localhost port=5432 dbname=my_pg user=user password=pw" -sql "update buildingtest set version=99"

-Jukka Rahkonen-

Lähettäjä: Andreas Oxenstierna <andreas.oxenstierna at t-kartor.com<mailto:andreas.oxenstierna at t-kartor.com>>
Lähetetty: torstai 9. kesäkuuta 2022 12.02
Vastaanottaja: gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>; Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>>
Aihe: Re: ogrinfo UPDATE performance request

Hi

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.
And to answer one other mail, the table name needs to be written as \"<schema>.<table>\", at least on macOS

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.

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.
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.

Best Regards

Andreas Oxenstierna
T-Kartor Geospatial AB
Olof Mohlins väg 12 Kristianstad
mobile: +46 733 206831
mailto: andreas.oxenstierna at t-kartor.com<mailto:andreas.oxenstierna at t-kartor.com>
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On 9 Jun 2022, 09:46 +0200, Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>>, wrote:
Hi,

Do not use "-dialect sqlite" if you play with PostgreSQL but let GDAL to use the native PG SQL dialect.

-Jukka Rahkonen-

Lähettäjä: gdal-dev <gdal-dev-bounces at lists.osgeo.org<mailto:gdal-dev-bounces at lists.osgeo.org>> Puolesta Andreas Oxenstierna
Lähetetty: torstai 9. kesäkuuta 2022 9.50
Vastaanottaja: gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>
Aihe: [gdal-dev] ogrinfo UPDATE performance request

Dear developers

Ogr SQL update capabilities are really impressing but there is one major performance issue with update of many features, exemplified by:
ogrinfo -dialect sqlite -sql "UPDATE <table> SET x = 1" PG:"<connection>"

This is painfully slow because ogr updates features one by one and furthermore updates all existing attributes incl. geometries.
Eg. updating 10000 features in pgAdmin/psql with UPDATE <table> SET x = 1 executes in milliseconds but takes several minutes with ogr.

The current ogr functionality is also not correct from a database transactional point of view.

I found an old RFC, https://gdal.org/development/rfc/rfc13_createfeatures.html<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>, requesting this but it was withdrawn for reasons not anymore digitally available.

Best Regards

Andreas Oxenstierna
T-Kartor Geospatial AB
Olof Mohlins väg 12 Kristianstad
mobile: +46 733 206831
mailto: andreas.oxenstierna at t-kartor.com<mailto:andreas.oxenstierna at t-kartor.com>
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