PostgreSQL (简体中文)

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本文档介绍如何安装PostgreSql,以及如何与PHPApache进行交互。同时,也介绍了如何配置PostgreSql,以使得远程服务端能够操作之。此处默认PHPApache 已经安装并配置完毕,如果您恰好没有安装此两个软件,请参考LAMP

安装PostgreSQL

  • 安装postgresql
$ sudo pacman -Sy postgresql
  • 启动PostgreSQL服务器 (第一次启动,将创建一个数据目录和需要使用此服务器的用户列表,此时,会看到大量的输出文字。)
$ sudo /etc/rc.d/postgresql start
  • 确认postgres用户创立成功,并且把该用户加入所属组postgres中。
$ groups postgres
  • (可选)把postgresql加入/etc/rc.conf中的daemons列表里,使系统启动时,postgresql作为守护进程同时启动。

创建第一个数据库

  • 成为postgres用户(此用户在执行"/etc/rc.d/postgres start"时已经被创建)
su root
su - postgres
  • 新增数据库用户:
createuser -DRSP <username>

-D User cannot create databases
-R User cannot create roles
-S User will not be a superuser
-P Prompt for password will be issued

Alternatively, you can use the createuser without parameter. Questions will be asked:

# createuser <username>
Shall the new role be a superuser? (y/n)  n
Shall the new role be allowed to create databases? (y/n)  y
Shall the new role be allowed to create more new roles? (y/n)  y

If you create a user as per your login user ($USER) it allows you to access the postgresql database shell without having to specify a user to login as (which makes it quite convenient).

  • Create a new database over which that user has read/write privileges
createdb -O username databasename [-E database_encoding]
  • That's It! Your database has been created.

Familiarizing Yourself with PostgreSQL

Access the database shell

  • Become the postgres user the first time, so we can assign permissions to you (your primary user)
$ sudo su postgres
  • Start the primary db shell, where you can do all your creation of databases/tables, deletion, set permissions, and run raw SQL commands.
$ psql
--You can optionally use `psql <database_name>` to administer an individual database.
  • Connect to a particular database
=> \c <database>
  • List all users and their permission levels
=> \du
  • Shows summary information about all tables in the current database
=> \dt

There are of course many more meta-commands, but these should help you get started.

Configure PostgreSQL to be accessible from remote

The PostgreSQL database server configuration file is postgresql.conf. This file is located in the data directory of the server, typically /var/lib/postgres/data. This folder also houses the other main config files, including the pg_hba.conf.

Note: By default this folder will not even be browseable (or searchable) by a regular user, if you are wondering why `find` or `locate` isn't finding the conf files, this is the reason (threw me for a loop the first time I installed).
  1. As root user edit the file
    $ sudo vim /var/lib/postgres/data/postgresql.conf
  2. In the connections and authentications section uncomment or edit the listen_addresses line to your needs
    listen_addresses = '*'
    and take a careful look at the other lines.
  3. Hereafter insert the following line in the host-based authentication file /var/lib/postgres/data/pg_hba.conf. This file controls which hosts are allowed to connect, so be careful.
    # IPv4 local connections: <br>host   all   all   your_desired_ip_address/32   trust
    whereas your_desired_ip_address is the ip address of the client.
  4. After this you should restart the daemon process for the changes to take effect with
    $ sudo /etc/rc.d/postgresql restart
Note: Postgresql uses port 5432 by default for remote connections. So make sure this port is open and able to receive incoming connections

For troubleshooting take a look in the server log file

tail /var/log/postgresql.log

Configure PostgreSQL to Work With PHP

  1. Install the PHP-PostgreSQL modules
    $ pacman -S php-pgsql 
  2. Open the file /etc/php/php.ini with your editor of choice, e.g.,
    # vim /etc/php/php.ini
  3. Find the line that starts with, ";extension=pgsql.so" and change it to, "extension=pgsql.so". (Just remove the preceding ";"). If you need PDO, do the same thing with ";extension=pdo.so" and ";extension=pdo_pgsql.so". If this lines are not present, add it. This lines may be in the "Dynamic Extensions" section of the file, or toward the very end of the file.
  4. Restart the Apache web server
    # /etc/rc.d/httpd restart

Installing phpPgAdmin (optional)

phpPgAdmin is a web-based administration tool for PostgreSQL. It can be installed two ways.

Option A: install via Pacman (preferred)

  1. Make sure that the [community] repo is enabled.
  2. Install the package via Pacman
    # pacman -Sy phppgadmin

Option B: install via a manual install (the old way)

  1. Download the latest .bz2 file from here into the root of your server directory
    wget -P /home/httpd/html http://downloads.sourceforge.net/phppgadmin/phpPgAdmin-4.1.3.tar.bz2
  2. Extract the file into the new directory
    tar -C /home/httpd/html/ -jxvf /home/httpd/html/phpPgAdmin-4.1.3.tar.bz2
  3. Remove the tar file
    rm /home/httpd/html/phpPgAdmin-4.1.3.tar.bz2
  4. Change the name of the directory created in the previous step to include the version number (this will help in the future when upgrading)
    mv /home/httpd/html/phpPgAdmin /home/httpd/html/phpPgAdmin-4.1.3/
  5. Create a link to that directory (for ease of linking and upgrading)
    ln -s /home/httpd/html/phpPgAdmin-4.1.3/ /home/httpd/html/phpPgAdmin
  6. Copy the included generic config file
    cp /home/httpd/html/phpPgAdmin/conf/config.inc.php-dist /home/httpd/html/phpPgAdmin/conf/config.inc.php


The config file is located at /home/httpd/html/phpPgAdmin/conf/config.inc.php. No changes should be required. Check this page for any other setup questions that you might have.

Upgrading Postgresql

Warning: Official postgresql upgrade documentation should be followed.

First thing: these instructions could cause data loss. Use at your own risk. They work for me, but things change and nothing is guaranteed.

I would highly suggest adding the line

IgnorePkg = postgresql

to /etc/pacman.conf. This will make sure that you don't accidentally upgrade the database to an incompatible version. If you did an accidental upgrade you might not be able to access any of your data. Always check the Postgresql home page (http://www.postgresql.org/) to be sure of what steps are required for each upgrade. For a bit about why this is the case see this.

How to dump all of your data, upgrade PostgreSQL, and then restore all of your data (this may not be necessary for every upgrade, see #2 above)

Become the root user

su

Become the postgres user

su postgres

Change the current directory to one that the postgres user can write to

eg. cd ~/data/

Dump the current contents of the database

pg_dumpall > pgs_db.out

Unless you have a .pgpass file setup, you will be required to enter your password a few times (the number of times is roughly equal to the number of databases that you have + 2). One problem occurs if you don't have a password defined for the postgres user but you require local users to authenticate. In this case you will be asked to give a password that doesn't exist. To work around this problem, add a line to your pg_hba.conf file to trust the postgres user. You can remove this line after the upgrade is complete. So, the first line of the 'local' section of pg_hba.conf would look something like this:

local     all postgres                                trust

Log out of the postgres user and return to superuser

exit

Stop the PostgreSQL server

/etc/rc.d/postgresql stop

Move Postgresql's data directory

mv /var/lib/postgres /var/lib/postgres_old

Upgrade postgresql

pacman -Sy postgresql

Start the PostgreSQL server (this will create all needed files and directories)

/etc/rc.d/postgresql start

Become the postgres user

su postgres

Change the current directory to the directory that you dumped the data out to (in step 4 above)

eg. cd /var/lib/postgres_old/data/

Restore the database

psql -e template1 -f pgs_db.out

More Resources