How to migrate from MySQL to PostgreSQL

# install packages
apt install postgresql pgloader

# create user and db
sudo -u postgres createuser etherpad
sudo -u postgres createdb -O etherpad etherpad

sudo -u postgres -i

# migrate db
cat <<EOF >>pgloader.load
LOAD DATABASE
        FROM mysql://etherpad:MYPASSWORD@127.0.0.1/etherpad
        INTO postgresql:///etherpad
WITH
        preserve index names,prefetch rows = 100
        alter schema 'etherpad' rename to 'public'
;
EOF

pgloader --verbose pgloader.load

psql etherpad

etherpad=# ALTER USER etherpad WITH PASSWORD 'NEW_PASSWORD';
etherpad=# GRANT pg_read_all_data TO etherpad;
etherpad=# GRANT pg_write_all_data TO etherpad;

Now continue normally to configure Etherpad-Lite to use PostgreSQL