How to merge from SpatialLite to PostGIS? - postgresql

Question

How can I merge a SpatiaLite database to a PostGIS database?
I tried to use pgloader with the following command:
pgloader db.sqlite3 postgresql:///mydb
But it is not working. (I guess it is not supported). Please see the error output:
KABOOM!
FATAL error: Could not prepare an sqlite statement.
Code ERROR: no such module: VirtualSpatialIndex.
Database: /tmp/db.sqlite3
SQL: PRAGMA table_info(`SpatialIndex`)
An unhandled error condition has been signalled:
Could not prepare an sqlite statement.
Code ERROR: no such module: VirtualSpatialIndex.
Database: /tmp/db.sqlite3
SQL: PRAGMA table_info(`SpatialIndex`)
FATAL: Failed to start the monitor thread.
error opening #P"/tmp/pgloader/pgloader.log": Permission denied
I use in SpatialLite only the simple POINT field. Nothing else from SpatialLite. (With Lat/Lng values)
EDIT1:
#Corion
If I try to do your way I get no error doing this:
pgloader --before load_spatialite.sql db.sqlite3
But loading it to PostGIS with this command:
pgloader --before load_spatialite.sql db.sqlite3 postgresql:///mydb
gives me the following error message:
2018-10-10T11:29:16.056000Z ERROR Database error 42883: function load_extension(unknown) does not exist
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
QUERY: SELECT load_extension('mod_spatialite')
KABOOM!
FATAL error: Database error 42883: function load_extension(unknown) does not exist
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
QUERY: SELECT load_extension('mod_spatialite')
An unhandled error condition has been signalled:
Database error 42883: function load_extension(unknown) does not exist
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
QUERY: SELECT load_extension('mod_spatialite')
What I am doing here?
Database error 42883: function load_extension(unknown) does not exist
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
QUERY: SELECT load_extension('mod_spatialite')
What is here the problem?

Answer 1

SpatiaLite is an extension built into SQLite. You will need an SQLite binary / library that is built with SpatiaLite linked statically or load the SpatiaLite dynamic extension (see link) while importing.
From staring at the pgloader manpage, it seems that you can prepend SQL commands to load the SpatiaLite extension into SQLite like this:
pgloader --before load_spatialite.sql /tmp/db.sqlite3
and load_spatialite.sql contains
SELECT load_extension('mod_spatialite');
You may or may not need to set up additional environment variables such that dynamic libraries are found for your process.