Upgrade PostgreSQL 9.4 to 10 (postgresql@9.4 to postgresql) version using Homebrew (macOS)

upgrade-postgres.sh

# I would recommend to run it step by step instead of running the whole script to detect and fix any issue that may come up.

# Stop if something went wrong
set -e;

# database host, mine is the default localhost
host=localhost

# db user, mine is the default postgres user
dbuser=postgres

# create a dir to contain all our dump databases and change directory into it
mkdir ~/dbdump && cd $_

# listing all databases and dumping them each one into it's file
psql -h $host -U $dbuser -t -A -c \ 
"SELECT datname FROM pg_database where datname not in ('template1', 'template0', 'postgres')" | \
while read db; do pg_dump -U $dbuser -h $host --clean --file="$db.sql" $db; end

# dump all globals for the cluster
# note use "-o" option to backup foreign keys
pg_dumpall -U postgres -h localhost -p 5433 --clean --globals-only --file=globals.sql

# stop the service
brew services stop postgresql@9.4

# Stop current server (if started manually)
# pg_ctl -D /usr/local/var/postgresql@9.4 stop

# unlink the current one
brew unlink postgresql@9.4

# install the new version
brew install postgresql

# start it up
brew services start postgresql

# create postgresuser
createuser -s postgres

# import globals first
psql -U $dbuser -h $host < globals.sql

# re-import each database file in the directory (except the globals)
# we read each one, split by the dot to get the database name, create the database and import from it's file.
# this will take some time, if you want to tackle each single database separately:
# createdb databasename && psql -h $host -U $dbuser databasename < databasename.sql
ls | grep -v global | while read filename; do \
db=$(echo $filename | cut -d'.' -f1); createdb "$db" && psql -h $host -U $dbuser "$db" < "$filename"; done

# Happy Hacking!