How to Start PostgreSQL Server on Mac OS X

To start the PostgreSQL server on Mac OS X, you need to use the pg_ctl command with the correct data directory path and ensure the service isn’t already running on the port. The most reliable method is brew services start postgresql if you installed via Homebrew, or using pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start for manual control. If the server still doesn’t start, you’ll need to check port conflicts, verify your configuration files, and ensure proper permissions.

• Basic PostgreSQL Server Startup
• Troubleshooting Common Issues
• Alternative Startup Methods
• Configuration File Setup
• Verifying Server Status
• Connection and Authentication

Basic PostgreSQL Server Startup

The standard command to start PostgreSQL manually on Mac OS X using Homebrew installation is:

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

This command tells PostgreSQL to:

• Use /usr/local/var/postgres as the data directory (-D flag)
• Write server logs to /usr/local/var/postgres/server.log (-l flag)
• Start the server process

Stack Overflow confirms this is the correct approach for manually starting PostgreSQL on Mac OS X.

If you installed PostgreSQL using Homebrew, there’s a more convenient method using Homebrew’s services system:

brew services start postgresql

This will start PostgreSQL and set it to automatically launch on system startup.

Troubleshooting Common Issues

Port Conflict Resolution

The server will only start if the port is free. If another PostgreSQL instance is already running on port 5432, you’ll need to stop it first:

# Check if any PostgreSQL process is running
pg_ctl -D /usr/local/var/postgres status

# If running, stop it
pg_ctl -D /usr/local/var/postgres stop

Atlassian emphasizes this important point about port conflicts.

Directory and File Permissions

Ensure your PostgreSQL data directory has proper permissions. The data directory should be owned by the postgres user:

# Set proper ownership
sudo chown -R postgres:postgres /usr/local/var/postgres

# Set appropriate permissions
sudo chmod 700 /usr/local/var/postgres

Log File Analysis

Check the server log file for error messages:

tail -f /usr/local/var/postgres/server.log

This will show you any specific errors preventing the server from starting. Chartio recommends examining the log file when troubleshooting startup issues.

Alternative Startup Methods

Using Homebrew Services

The recommended approach for Homebrew installations:

# Start and enable automatic startup
brew services start postgresql

# Stop and disable automatic startup
brew services stop postgresql

# Restart the service
brew services restart postgresql

This method is preferred as it integrates with macOS’s launchd system for proper service management.

Manual Start with Logging

For debugging purposes, you can start with more verbose logging:

pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start -o "-c log_statement=all"

The additional -o flag enables statement logging for detailed debugging.

Starting with Specific Options

You can pass PostgreSQL configuration options during startup:

# Start with custom port
pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start -o "-p 5433"

# Start with specific configuration
pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start -o "-c listen_addresses='*'"

Configuration File Setup

postgresql.conf Configuration

Your postgresql.conf file should be properly configured. Key settings include:

# Listen on all addresses (or specific ones)
listen_addresses = '*'

# Port configuration
port = 5432

# Logging configuration
logging_collector = on
log_directory = 'pg_log'
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

pg_hba.conf Authentication

The pg_hba.conf file controls client authentication. For local development, you typically want:

# Allow local connections with any authentication method
local   all             all                                     trust
# Allow IPv4 local connections
host    all             all             127.0.0.1/32            trust
# Allow IPv6 local connections
host    all             all             ::1/128                 trust

PostgreSQL Documentation provides comprehensive information on configuration file settings.

Verifying Server Status

Status Commands

After starting PostgreSQL, verify the server is running:

# Check status
pg_ctl -D /usr/local/var/postgres status

# Alternative status check
ps aux | grep postgres

# Check if listening on port 5432
lsof -i :5432

Connection Testing

Test basic connectivity to the server:

# Using psql
psql -h localhost -U postgres -d postgres

# Or using the postgres command
postgres -h localhost -U postgres -d postgres

Connection and Authentication

Ruby on Rails Connection Issues

If you’re getting the error “Is the server running on host ‘localhost’ and accepting TCP/IP connections on port 5432?” in Ruby on Rails, check:

1. Database Configuration: Ensure your database.yml has the correct host and port:

development:
  adapter: postgresql
  encoding: unicode
  database: your_database_name
  pool: 5
  username: your_username
  password: your_password
  host: localhost
  port: 5432

2. User Privileges: Ensure your database user has proper permissions:

-- Grant necessary privileges
GRANT ALL PRIVILEGES ON DATABASE your_database_name TO your_username;

3. Network Configuration: If connecting from outside localhost, ensure PostgreSQL is configured to accept remote connections in postgresql.conf:

listen_addresses = '*'

Creating Database Users

Create a dedicated user for your Rails application:

-- Create user with password
CREATE USER your_username WITH PASSWORD 'your_password';

-- Create database owned by this user
CREATE DATABASE your_database_name OWNER your_username;

DEV Community provides additional tips for PostgreSQL setup on macOS.

Sources

1. Stack Overflow - How can I start PostgreSQL server on Mac OS X?
2. Atlassian - How to start a PostgreSQL server on Mac OS X
3. Atlassian - Starting PostgreSQL on Mac with Homebrew
4. Sourabh Bajaj - PostgreSQL | macOS Setup Guide
5. Codementor - Getting Started with PostgreSQL on Mac OSX
6. Chartio - Starting PostgreSQL Server on Mac OS X via Homebrew
7. Robin Wieruch - How to setup PostgreSQL on MacOS
8. DEV Community - Easy setup PostgreSQL on MacOS
9. Reddit - r/PostgreSQL: Is there a way to start the server in the app from the terminal? (MacOS)
10. PostgreSQL Documentation: 18.3. Starting the Database Server

Conclusion

Starting PostgreSQL on Mac OS X requires understanding the proper command syntax and common troubleshooting steps. The key takeaways are:

1. Use Homebrew services (brew services start postgresql) for the most reliable startup method if you installed via Homebrew
2. Check for port conflicts - ensure no other PostgreSQL instance is already running on port 5432
3. Verify configuration files - ensure postgresql.conf and pg_hba.conf are properly set up
4. Examine log files - check /usr/local/var/postgres/server.log for specific error messages
5. Test connectivity - use psql or other tools to verify the server is accepting connections

If you’re still having issues, consider reinstalling PostgreSQL with Homebrew (brew reinstall postgresql) or checking for any system-level restrictions that might prevent the database from starting properly. For persistent connection issues in Ruby on Rails, double-check your database.yml configuration and ensure your database user has the necessary privileges.