How can I decrease size of geodatabase "Nominatim"?

The speed of geocoding relies on two main points for a server that has the good capacities : increasing shared_buffers to 2Go in the postgresql.conf file and waiting for the index to complete : this can take much time. On my server with a test concerning the database of France only, geocoding went faster after 2 or 3 days.

If you want to index and leave the terminal session you can use the nohup command under unix like systems for example.

If you decrease the size of database as mentionned in the manual with the --drop argument, this will impact updates.