'brew pin does not prevent upgrading of postgresql formula

I am trying to prevent my current version of posgtgresql being upgraded. Accordingly I did brew pin postgresql@12. However I am finding that if I do

pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start

I get the following error message

        waiting for server to start.... stopped waiting
    pg_ctl: could not start server

Examine the log output.

Looking at the log output, the last lines are

2022-05-01 17:31:00.816 AEST [18650] FATAL:  database files are incompatible with server
2022-05-01 17:31:00.816 AEST [18650] DETAIL:  The data directory was initialized by PostgreSQL version 12, which is not compatible with this version 14.2.

so postgresql has been updated to version 14.2.

If I do brew list --pinned it shows

postgresql@10
postgresql@11
postgresql@12

so I am still have postgresql@12 pinned. So why has the pinning not worked, and how do I restore posgresql to version 12?

I notice that if I do brew services list I see

postgresql    none           
postgresql@10 none           
postgresql@11 none           
postgresql@12 error  6 Chris ~/Library/LaunchAgents/[email protected]

i.e. postgresql@14 is not listed, so perhaps postgresql was upgraded in some other manner than using brew? However, I certainly did not do explicit upgrade, so do not see how this could have happened.

postgresqlhomebrew


Solution 1:[1]

In lieu of an answer to this question, the way I recover from this situation is explained in this SO answer.

In brief (warning this destroys the databases)

brew uninstall --force postgresql
brew install postgresql@12
cd /usr/local/var/
rm -rf postgres
initdb /usr/local/var/postgres

Trying to look on the bright side, it is an opportunity to upgrade your databases by either a minor or major version.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Obromios

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