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 postgresql@9.6 // 这一步如果已经安装了，则可以跳过
brew unlink postgresql@9.6
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/postgresql@9.6/9.6.10/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 postgresql@9.6
rm -rf /usr/local/var/postgres96
rm -rf /usr/local/share/postgresql96 一切OK
