Postgres无法连接到服务器
本文翻译自：Postgres could not connect to server
After I did brew update and brew upgrade, my postgres got some problem. 在我做了brew更新和brew升级之后，我的postgres遇到了一些问题。 I tried to uninstall postgres and install again, but it didn't work as well. 我试图卸载postgres并重新安装，但它也没有用。
This is the error message.(I also got this error message when I try to do rake db:migrate) 这是错误消息。（当我尝试执行rake db：migrate时，我也收到此错误消息）
$ psql
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
How can I solve it? 我该如何解决？
Mac version: Mountain lion. Mac版：山狮。
homebrew version: 0.9.3 自制版：0.9.3
postgres version: psql (PostgreSQL) 9.2.1 postgres版本：psql（PostgreSQL）9.2.1
And this is what I did. 这就是我所做的。
12:30 ~/D/works$ brew uninstall postgresql
Uninstalling /usr/local/Cellar/postgresql/9.2.1...
12:31 ~/D/works$ brew uninstall postgresql
Uninstalling /usr/local/Cellar/postgresql/9.1.4...
12:31 ~/D/works$ psql --version
bash: /usr/local/bin/psql: No such file or directory
12:33 ~/D/works$ brew install postgresql
==> Downloading http://ftp.postgresql.org/pub/source/v9.2.1/postgresql-9.2.1.tar.bz2
Already downloaded: /Library/Caches/Homebrew/postgresql-9.2.1.tar.bz2
......
......
==> Summary
/usr/local/Cellar/postgresql/9.2.1: 2814 files, 38M, built in 2.7 minutes
12:37 ~/D/works$ initdb /usr/local/var/postgres -E utf8
The files belonging to this database system will be owned by user "laigary".
This user must also own the server process.
The database cluster will be initialized with locale "en_US.UTF-8".
The default text search configuration will be set to "english".
initdb: directory "/usr/local/var/postgres" exists but is not empty
If you want to create a new database system, either remove or empty
the directory "/usr/local/var/postgres" or run initdb
with an argument other than "/usr/local/var/postgres".
12:39 ~/D/works$ mkdir -p ~/Library/LaunchAgents
12:39 ~/D/works$ cp /usr/local/Cellar/postgresql/9.2.1/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/
12:39 ~/D/works$ launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
homebrew.mxcl.postgresql: Already loaded
12:39 ~/D/works$ pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
server starting
12:39 ~/D/works$ env ARCHFLAGS="-arch x86_64" gem install pg
Building native extensions. This could take a while...
Successfully installed pg-0.14.1
1 gem installed
12:42 ~/D/works$ psql --version
psql (PostgreSQL) 9.2.1
12:42 ~/D/works$ psql
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
Now, after I reinstalled howbrew,when I use $ psql , It doesn't show any error message. 现在，在我重新安装了问题之后，当我使用$ psql ，它没有显示任何错误消息。
But I run rake db:migrate in my rails app, it shows: 但我在我的rails应用程序中运行rake db:migrate ，它显示：
could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `initialize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `new'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:1213:in `connect'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:329:in `initialize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `new'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `postgresql_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:309:in `new_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:319:in `checkout_new_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:241:in `block (2 levels) in checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:236:in `loop'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:236:in `block in checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:233:in `checkout'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:96:in `block in connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:404:in `retrieve_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:170:in `retrieve_connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/connection_adapters/abstract/connection_specification.rb:144:in `connection'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:107:in `rescue in create_database'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:51:in `create_database'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `block (3 levels) in <top (required)>'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/gems/1.9.1/gems/activerecord-3.2.8/lib/active_record/railties/databases.rake:40:in `block (2 levels) in <top (required)>'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:205:in `call'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:205:in `block in execute'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:200:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:200:in `execute'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:158:in `block in invoke_with_call_chain'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:151:in `invoke_with_call_chain'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/task.rb:144:in `invoke'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:116:in `invoke_task'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `block (2 levels) in top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `each'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:94:in `block in top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:133:in `standard_exception_handling'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:88:in `top_level'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:66:in `block in run'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:133:in `standard_exception_handling'
/usr/local/Cellar/ruby/1.9.3-p327/lib/ruby/1.9.1/rake/application.rb:63:in `run'
/usr/local/bin/rake:32:in `<main>'
Couldn't create database for {"adapter"=>"postgresql", "encoding"=>"unicode", "database"=>"riy_development", "pool"=>5, "username"=>nil, "password"=>nil}
Finally I find the solution. 最后我找到了解决方案。
$ sudo mkdir /var/pgsql_socket/
$ sudo ln -s /private/tmp/.s.PGSQL.5432 /var/pgsql_socket/
This solution is little tricky, but it works. 这个解决方案有点棘手，但它确实有效。 Hope anyone have a better solution 希望有人有更好的解决方案
Update 更新
This works for me as well. 这对我也有用。
rm /usr/local/var/postgres/postmaster.pid
#1楼
参考：https://stackoom.com/question/uGjO/Postgres无法连接到服务器
#2楼
Check that the socket file exists. 检查套接字文件是否存在。
$ ls -l /tmp/.s.PGSQL.5432
srwxrwxrwx 1 you wheel 0 Nov 16 09:22 /tmp/.s.PGSQL.5432
If it doesn't then check your postgresql.conf for unix_socket_directory change. 如果没有，则检查postgresql.conf以获取unix_socket_directory更改。
$ grep unix_socket /usr/local/var/postgres/postgresql.conf
#unix_socket_directory = '' # (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
#3楼
For anyone reading this and using Postgres.app, you may need host: localhost in your database.yml. 对于阅读此内容并使用Postgres.app的任何人，您可能需要在database.yml中使用host: localhost 。 http://postgresapp.com/documentation#toc_3 http://postgresapp.com/documentation#toc_3
#4楼
Changing postresql or database.yml config settings, changing $PATH, or creating symlinks were all unnecessary for me. 更改postresql或database.yml配置设置，更改$ PATH或创建符号链接对我来说都是不必要的。 All I needed to do was gem uninstall pg and then bundle (or gem install pg ). 我需要做的就是gem uninstall pg然后bundle （或gem install pg ）。
The issue was that the pg gem had been installed before homebrew postgres, so was picking up the settings from the version of postgres that comes with MacOS. 问题是pg gem已经在自制的postgres之前安装了，所以从MacOS附带的postgres版本中获取了设置。 Reinstalling it (and thus rebuilding the native extension) fixed the problem. 重新安装它（从而重建原生扩展）修复了问题。
#5楼
Had a similar problem; 有类似的问题; a pid file was blocking postgres from starting up. 一个pid文件阻止postgres启动。 To fix it: 要解决这个问题：
rm /usr/local/var/postgres/postmaster.pid
and then all is well. 然后一切都很好。
#6楼
I ran into this issue after trying to restore/drop/create a db while other processes were accessing them. 在尝试恢复/删除/创建数据库时，我遇到了这个问题，而其他进程正在访问它们。 MacOSX/Homebrew fix was: MacOSX / Homebrew修复是：
- close all other accessing processes
rails server,rails console,guard, etc... 关闭所有其他访问进程rails server，rails console，guard等... - load/unload using the commands found in
brew info postgres使用brew info postgres的命令加载/卸载 - run restore/drop/create from before 从之前运行restore / drop / create