初次使用PostgreSQL发现了一个问题， 就是在使用mac中使用brew安装PostgreSQL时，会自动进行版本升级，但是再进行版本升级的时候会遇到如下错误

could not open version file: /usr/local/var/postgres.old/PG_VERSION

经过搜索，这里找到了解决办法如下地址

https://gist.github.com/giannisp/ebaca117ac9e44231421f04e7796d5ca

但是从内容上可以看到版本是从9.6.5到10.0
Upgrade PostgreSQL 9.6.5 to 10.0 using Homebrew (macOS)

本次分享下从9.6.10到10.3
Upgrade PostgreSQL 9.6.10 to 10.3 using Homebrew (macOS)

流程是一样的，但是记录下

need to have both 9.6.x and latest 10.0 installed, and keep 10.0 as default

brew unlink postgresql
brew install [email protected] // 这一步如果已经安装了，则可以跳过
brew unlink [email protected]
brew link postgresql

move 9.6.x db files to another directory

mv /usr/local/var/postgres /usr/local/var/postgres96

init new database using 10.3

initdb /usr/local/var/postgres -E utf8

make timezone and timezonesets directories available for 9.6.x installation

mkdir /usr/local/share/postgresql96
cp -r /usr/local/share/postgresql/timezone /usr/local/share/postgresql96
cp -r /usr/local/share/postgresql/timezonesets /usr/local/share/postgresql96

finally the actual upgrade

-b is the old binary dir, -B is the new binary dir

-d is the old data dir, -D is the new data dir

pg_upgrade -b /usr/local/Cellar/[email protected]/9.6.10/bin -B /usr/local/Cellar/postgresql/10.3/bin -d /usr/local/var/postgres96 -D /usr/local/var/postgres

start 10.3 to check that upgrade works

pg_ctl start -D /usr/local/var/postgres

cleanup if upgrade was successful

brew uninstall [email protected]
rm -rf /usr/local/var/postgres96
rm -rf /usr/local/share/postgresql96

一切OK