Complete overhaul of country grid generation algorithm #1
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See README for new algorithm.
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Extended the SQL, so that most of the simplification necessary to get to a country table of a managable size can be done with some simple SQL. This makes use of the new ST_CoverageSimplify function from PostGIS. IT allows to simplify boundaries between countries without loosing coverage. Needs PostGIS 3.4, which is available in Ubuntu 24.04.
The data file on nominatim.org already has a new country grid generated with this algorithm. With the simplification the file size has shrunk from 41MB to 15MB, and the table size from 49MB to 27MB. All this despite the fact that accuracy of boundaries has improved quite a lot in the last 5 years in OSM.
For more information see also the README.