Homebrew PostgreSQL 啟動狀態錯誤 status error 256

終端機執行brew services start postgresql啟動Homebrew安裝的PostgreSQL資料庫時狀態為error 256錯誤。

環境：

• MacBook Pro Intel Core i5
• macOS Ventura 13.2.1
• Homebrew 4.0.3
• psql (PostgreSQL) 14.5 (Homebrew)

~% brew services start postgresql@14
==> Successfully started `postgresql@14` (label: homebrew.mxcl.postgresql@14)
~% brew services list
Name          Status     User  File
postgresql@14 error  256 user  ~/Library/LaunchAgents/homebrew.mxcl.postgresql@14.plist

原因

錯誤原因是PostgreSQL安裝目錄的postmaster.pid檔可能因PostgreSQL程序未正常關閉沒被刪除，導致啟動PostgreSQL服務時發現此檔案已存在而無法成功啟動。postmaster.pid是一個lock file，作用為用來防止同時多個資料庫實例程序使用同一份資料目錄(data directory)。

解決

先執行brew services stop postgresql@14將PostgreSQL服務停止。

~% brew services stop postgresql@14
==> Downloading https://formulae.brew.sh/api/formula.json
######################################################################## 100.0%
Stopping `postgresql@14`... (might take a while)
==> Successfully stopped `postgresql@14` (label: homebrew.mxcl.postgresql@14)

然後執行rm -f /usr/local/var/postgresql@14/postmaster.pid將postmaster.pid檔刪除。

~% rm -f /usr/local/var/postgresql@14/postmaster.pid

Mac M1是執行rm -f /opt/homebrew/var/postgresql@14/postmaster.pid。

~% rm -f /opt/homebrew/var/postgresql@14/postmaster.pid

再執行brew services start postgresql@14啟動。

~% brew services start postgresql@14
==> Successfully started `postgresql@14` (label: homebrew.mxcl.postgresql@14)

執行brew services list檢查服務狀態為正常。

~% brew services list
Name          Status  User  File
postgresql@14 started user  ~/Library/LaunchAgents/homebrew.mxcl.postgresql@14.plist

• 19.3. Starting the Database Server
• Cannot connect to Postgres server running through brew services
• Re: FATAL: lock file "postmaster.pid" already exists