PostgreSQL (简体中文)
PostgreSQL是一个开源的,社区驱动的,符合标准的 对象-关系型 数据库系统。
本文档介绍如何安装PostgreSql。同时,也介绍了如何配置PostgreSql,以使得远程服务端能够操作之。如果你需要帮助建立一个网络栈的其余部分,请参照 LAMP 的所有部分,除了涉及到 MySQL 的那一部分。
Contents
开始之前
有些地方会有“以 postgres 用户身份”的指示。请执行以下操作,以 postgres 用户获得一个 shell:
su root su - postgres
否则,使用 sudo 命令:
sudo -i -u postgres
安装PostgreSQL
安装 postgresql 。在PostgreSQL可以正确使用之前,postgres 用户需要被赋予几个文件与目录的所有权,以及数据库集群必须被初始化。以下步骤使用了默认配置。
Create "volatile and temporary files and directories". 具体信息参考Systemd#Temporary_files:
# systemd-tmpfiles --create postgresql.conf
创建数据文件夹,赋予正确的权限以及初始化数据库集群:
# mkdir /var/lib/postgres/data # chown -c -R postgres:postgres /var/lib/postgres # sudo su - postgres -c "initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'"
启动PostgreSQL,(可选),添加 PostgreSQL 到daemons列表里作为守护进程同时启动:
# systemctl start postgresql # systemctl enable postgresql
创建第一个数据库/用户
以postgres用户身份, 添加一个新的数据库用户使用createuser 命令
如果一个创建与你的Arch用户($USER)同名的数据库用户,并允许访问PostgreSQL数据库的shell,那么在使用PostgreSQL数据库shell的时候无需指定用户登录(这样做会比较方便)。
例如:创建一个超级用户
$ createuser -s -U postgres --interactive
输入要增加的角色名称: 我登录Arch的用户名
以具备读写权限的用户身份,创建一个新的数据库,使用createdb 命令。
从你的shell (不是 以postrgres用户的身份)
$ createdb myDatabaseName
熟悉PostgreSQL
Access the database shell
Become the postgres user. Start the primary db shell, psql, where you can do all your creation of databases/tables, deletion, set permissions, and run raw SQL commands. Use the "-d" option to connect to the database you created (without specifying a database, psql will try to access a database that matches your username)
$ psql -d myDatabaseName
一些有用的命令:
- 帮助
=> \help
- 连接到数据库<database>
=> \c <database>
- 列出所有用户以及他们的权限
=> \du
- 展示当前数据库中所有的表相关的汇总信息
=> \dt
- 退出psql
=> \q or CTRL+d
当然也有更多元命令,但这些应该能够帮助您开始。
配置 PostgreSQL 被远程访问
PostgreSQL Server 的配置文件是 postgresql.conf
。此文件在数据库数据目录中,通常在 /var/lib/postgres/data
. 这个目录也包含其他主要的配置文件,包括 pg_hba.conf
。
As root user edit the file /var/lib/postgres/data/postgresql.conf
.
In the connections and authentications section uncomment or edit the listen_addresses
line to your needs:
listen_addresses = '*'
Take a careful look at the other lines.
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: host all all your_desired_ip_address/32 trust
where your_desired_ip_address
is the IP address of the client.
After this you should restart the daemon process for the changes to take effect with:
# systemctl restart postgresql
For troubleshooting take a look in the server log file
tail /var/log/postgresql.log
Configure PostgreSQL to work with PHP
Install the PHP-PostgreSQL modules php-pgsql.
Edit the file /etc/php/php.ini
. Find the line that starts with:
;extension=pgsql.so
Change it to:
extension=pgsql.so
If you need PDO, do the same thing with ;extension=pdo.so
and ;extension=pdo_pgsql.so
. If these lines are not present, add them. These lines may be in the "Dynamic Extensions" section of the file, or toward the very end of the file.
Restart the Apache web server:
- systemctl restart httpd
Change default data dir (optional)
The default directory where all your newly created databases will be stored is /var/lib/postgres/data
. To change this, follow these steps:
Create the new directory and assign it to user postgres
(you eventually have to become root):
mkdir -p /pathto/pgroot/data chown -R postgres:postgres /pathto/pgroot
Become the postgres user(change to root, then postgres user), and initialize the new cluster:
initdb -D /pathto/pgroot/data
If not using systemd, edit /etc/conf.d/postgresql
and change the PGROOT variable(optionally PGLOG) to point to your new pgroot directory:
#PGROOT="/var/lib/postgres/" PGROOT="/pathto/pgroot/"
If using systemd, edit /etc/systemd/system/multi-user.target.wants/postgresql.service
, which links to /usr/lib/systemd/system/postgresql.service
, and change the default PGROOT path.
#Environment=PGROOT=/var/lib/postgres/ Environment=PGROOT=/pathto/pgroot/
You will also need to change the default PIDFile path.
PIDFile=/pathto/pgroot/data/postmaster.pid
Change default encoding of new databases to UTF-8 (optional)
When creating a new database (e.g. with createdb blog
) PostgreSQL actually copies a template database. There are two predefined templates: template0 is vanilla, while template1 is meant as an on-site template changeable by the administrator and is used by default. In order to change the encoding of new database, one of the options is to change on-site template1. To do this, log into PostgresSQL shell (psql) and execute the following:
First, we need to drop template1. Templates cannot be dropped, so we first modify it so it is an ordinary database:
UPDATE pg_database SET datistemplate = FALSE WHERE datname = 'template1';
Now we can drop it:
DROP DATABASE template1;
The next step is to create a new database from template0, with a new default encoding:
CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
Now modify template1 so it is actually a template:
UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
(OPTIONAL) If you do not want anyone connecting to this template, set datallowconn to FALSE:
UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
Now you can create a new database by running from regular shell:
su - su - postgres createdb blog;
If you log in back to psql and check the databases, you should see the proper encoding of your new database:
\l
returns
List of databases Name | Owner | Encoding | Collation | Ctype | Access privileges -----------+----------+-----------+-----------+-------+---------------------- blog | postgres | UTF8 | C | C | postgres | postgres | SQL_ASCII | C | C | template0 | postgres | SQL_ASCII | C | C | =c/postgres : postgres=CTc/postgres template1 | postgres | UTF8 | C | C |
管理工具
- phpPgAdmin — Web-based administration tool for PostgreSQL.
- pgAdmin — GUI-based administration tool for PostgreSQL.
Postgresql升级配置
快速指南
This is for upgrading from 9.2 to 9.3.
pacman -S --needed postgresql-old-upgrade su - su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/data-9.2' su - postgres -c 'mkdir /var/lib/postgres/data' su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'
If you had custom settings in configuration files like pg_hba.conf and postgresql.conf, merge them into the new ones. Then:
su - postgres -c 'pg_upgrade -b /opt/pgsql-9.2/bin/ -B /usr/bin/ -d /var/lib/postgres/data-9.2 -D /var/lib/postgres/data'
If the "pg_upgrade" step fails with:
- cannot write to log file pg_upgrade_internal.log
Failure, exiting
Make sure you're in a directory that the "postgres" user has enough rights to write the log file to (/tmp
for example). Or use "su - postgres" instead of "sudo -u postgres". - LC_COLLATE error that says that old and new values are different
Figure out what the old locale was, C or en_US.UTF-8 for example, and force it when calling initdb.
sudo -u postgres LC_ALL=C initdb -D /var/lib/postgres/data
- There seems to be a postmaster servicing the old cluster.
Please shutdown that postmaster and try again.
Make sure postgres isn't running. If you still get the error then chances are these an old PID file you need to clear out.
> sudo -u postgres ls -l /var/lib/postgres/data-9.2 total 88 -rw------- 1 postgres postgres 4 Mar 25 2012 PG_VERSION drwx------ 8 postgres postgres 4096 Jul 17 00:36 base drwx------ 2 postgres postgres 4096 Jul 17 00:38 global drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_clog -rw------- 1 postgres postgres 4476 Mar 25 2012 pg_hba.conf -rw------- 1 postgres postgres 1636 Mar 25 2012 pg_ident.conf drwx------ 4 postgres postgres 4096 Mar 25 2012 pg_multixact drwx------ 2 postgres postgres 4096 Jul 17 00:05 pg_notify drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_serial drwx------ 2 postgres postgres 4096 Jul 17 00:53 pg_stat_tmp drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_subtrans drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_tblspc drwx------ 2 postgres postgres 4096 Mar 25 2012 pg_twophase drwx------ 3 postgres postgres 4096 Mar 25 2012 pg_xlog -rw------- 1 postgres postgres 19169 Mar 25 2012 postgresql.conf -rw------- 1 postgres postgres 48 Jul 17 00:05 postmaster.opts -rw------- 1 postgres postgres 80 Jul 17 00:05 postmaster.pid # <-- This is the problem > sudo -u postgres mv /var/lib/postgres/data-9.2/postmaster.pid /tmp
- ERROR: could not access file "$libdir/postgis-2.0": No such file or directory
Retrieve postgis-2.0.so from postgis package for version postgresql 9.2 () and copy it to /opt/pgsql-9.2/lib (make sure the privileges are right)
详细说明
需要注意的是,这些指令可能会导致数据丢失。 后果自负.
推荐把下面的加入你的 /etc/pacman.conf
文件中:
IgnorePkg = postgresql postgresql-libs
这将确保你不会不小心将数据库升级到不兼容的版本中。当一个升级可用时,pacman将通知你,因为在pacman.conf中的设置,它跳过了升级。小版本升级 (e.g., 9.0.3 to 9.0.4) 可以被安全地执行。不过,当如果你突然做一个不同的主版本升级时,(e.g., 9.0.X to 9.1.X), 您可能无法访问你的任何数据。请务必检查PostgreSQL的主页 (http://www.postgresql.org/) ,以确认每次升级所需要的步骤。对于为什么是这种情况见 versioning policy。
主要有两种方式来升级您的PostgreSQL数据库。阅读官方文档细节。
For those wishing to use pg_upgrade
, a postgresql-old-upgrade package is available in the repositories that will always run one major version behind the real PostgreSQL package. This can be installed side by side with the new version of PostgreSQL. When you are ready to perform the upgrade, you can do
pacman -Syu postgresql postgresql-libs postgresql-old-upgrade
Note also that the data directory does not change from version to version, so before running pg_upgrade it is necessary to rename your existing data directory and migrate into a new directory. The new database must be initialized by starting the server, as described near the top of this page. The server then needs to be stopped before running pg_upgrade.
# systemctl stop postgresql # su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata' # systemctl start postgresql # systemctl stop postgresql
Reference the upstream pg_upgrade documentation for details.
The upgrade invocation will likely look something like the following (run as the postgres user). Do not run this command blindly without understanding what it does!
# su - postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-8.4/bin/ -B /usr/bin/'
You could also do something like this (after the upgrade and install of postgresql-old-upgrade) (NB: these instructions DON'T seem to work for 9.2 -> 9.3 upgrades)
# systemctl stop postgresql # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start # pg_dumpall >> old_backup.sql # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop # systemctl start postgresql # psql -f old_backup.sql postgres
Troubleshooting
Improve performance of small transactions
If you are using PostgresSQL on a local machine for development and it seems slow, you could try turning synchronous_commit off in the configuration (/var/lib/postgres/data/postgresql.conf
). Beware of the caveats, however.
synchronous_commit = off
空闲时防止磁盘写入
PostgreSQL periodically updates its internal "statistics" file. By default, this file is stored on disk, which prevents disks spinning down on laptops and causes hard drive seek noise. It's simple and safe to relocate this file to a memory-only file system with the following configuration option:
stats_temp_directory = '/run/postgresql'