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I have data stored in an AWS RDS PostgreSQL database with the PostGIS extension enabled. When I connect to the data from within QGIS (2.18.2) the data types are not preserved. For example a column of type 'bigint' (in PostgreSQL)

enter image description here

is converted to qlonglong int8 (in QGIS): enter image description here

The problem arises when I export the data to another file format (e.g. GPKG). integer columns are saved as doubles. The data type should be integer 64 bit / 8 byte. How can I convert a postgis table with bigint to geopackage without converting the bigint to double? (preferably without extra steps)

PostgreSQL version:

PostgreSQL 9.6.6 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.3 20140911 (Red Hat 4.8.3-9), 64-bit

PostGIS version:

POSTGIS="2.3.4 r16009" GEOS="3.6.2-CAPI-1.10.2 4d2925d6" PROJ="Rel. 4.9.3, 15 August 2016" GDAL="GDAL 2.1.3, released 2017/20/01" LIBXML="2.9.1" LIBJSON="0.12" TOPOLOGY RASTER
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    were there any intermediate steps included? did you edit the layer? – ThingumaBob Nov 28 '18 at 13:29
  • Yes, I joined a csv layer to the table. It seems like this caused the problem. – RutgerH Nov 28 '18 at 14:01
  • I don't think QGIS is not changing the data types, it just reads them differently. For example, we have smallint in the PGIS database, but QGIS reads them as int2 - for all intents and purposes, the data is the same. – DPSSpatial Nov 28 '18 at 16:19
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I can't seem to reproduce your issue, neither with QGIS 2.18 nor 3.4 (on Ubuntu 18.04, PostgreSQL 10/PostGIS 2.5); while QGIS uses qlonglong internally, the exported GPKG DB layer reports integer64 (note that I haven't altered the layer in any way).

Anyway, ogr2ogr should convert src type to the appropriate dst type (i.e. SQLite's unique value typing system, INTEGERs (integer64) in this case):

ogr2ogr -f GPKG path/to/dst.gpkg PG:"host=<host> port=<port> dbname=<dbname> user=<user> password=<password>" schema.table -append
  • ...not sure if directly drag'n'drop the PostGIS layer into the GPKG in the Browser can help avoiding type conversions? – ThingumaBob Nov 28 '18 at 13:27
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    It seems like an intermediate Join caused the errors. – RutgerH Nov 28 '18 at 14:02

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