Upgrading from PostgreSQL 12 to 17 in Rails (via Homebrew MACOS)@gekong

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This guide walks through upgrading your local PostgreSQL setup from version 12 to 17 for a Rails application on macOS using Homebrew, while preserving data and ensuring your Rails app keeps working.

✅ Overview

Tools Involved:

PostgreSQL (brew install postgresql@17)
pg_upgrade for migrating old data
Ruby on Rails + pg gem
Homebrew service management
libpq for client libraries

🔧 Steps

1. Install PostgreSQL 17

bashCopyEditbrew install postgresql@17

Ensure it's linked correctly:

bashCopyEditbrew link postgresql@17 --force

2. Check for Binary Version Mismatches

Make sure initdb and postgres match:

bashCopyEditinitdb --version
postgres --version

If mismatched, uninstall libpq and reinstall PostgreSQL:

bashCopyEditbrew uninstall libpq
brew reinstall postgresql@17

3. Initialize PostgreSQL 17 Data Directory

If needed:

bashCopyEditrm -rf /opt/homebrew/var/postgresql@17
initdb -D /opt/homebrew/var/postgresql@17

4. Stop Postgres 17 Before Upgrading

bashCopyEditbrew services stop postgresql@17

5. Run pg_upgrade to Migrate Data

bashCopyEditpg_upgrade \
  -b /opt/homebrew/opt/postgresql@12/bin \
  -B /opt/homebrew/opt/postgresql@17/bin \
  -d /opt/homebrew/var/postgresql@12 \
  -D /opt/homebrew/var/postgresql@17

6. Start PostgreSQL 17

bashCopyEditbrew services start postgresql@17

7. Fix Rails pg Gem Dynamic Linking Error

The Rails app may crash with a libpq.5.dylib error.

Fix it by reinstalling and linking libpq:

bashCopyEditbrew install libpq
brew link --force libpq

8. Confirm Everything Works

Start Rails server:
```
bash
```
```
CopyEdit
```
```
rails s
```
Check your app connects and loads data as expected

🧹 Optional Cleanup

After verifying everything:

bashCopyEditrm -rf /opt/homebrew/var/postgresql@12
./delete_old_cluster.sh  # optional, auto-generated by pg_upgrade

🏁 You're Done!

Your Rails app is now fully upgraded to PostgreSQL 17 🎉
All data was preserved, and your environment is clean and up to date.

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the goal is to update the postgresql install and connected to my local database on my rails app Created: June 8, 2025 9:23am

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