PostgreSQL 12 High Availability Cookbook - Third Edition

How to do it...

For this recipe, we should still have three PostgreSQL servers. As usual, we'll assume they are named pgha1, pgha2, and pgha3. If pgha1 is the initial leader, follow these steps to perform an in-place system upgrade:

1. Start a status monitor on pgha3 with the following command executed as the postgres user:

patronictl -d localhost:2379 list -w 5 stampede

2. Execute the following command on any node as the postgres user to initiate a switchover from pgha1 to pgha2:

patronictl -d localhost:2379 switchover \
    --master pgha1 --candidate pgha2 \
    --scheduled now --force stampede

3. Verify that pgha2 has assumed the cluster leadership role. The status screen should eventually resemble this output:

4. As a root-enabled user on ...