PostgreSQL

Updated 7 Mai 2021

PostgreSQL

PostgreSQL is a free object-relational database system.

Installation

Install PostgreSQL:

emerge -a dev-db/postgresql

Setup PostgresSQL:

emerge --config postgresql
Configuring pkg...

 * You can modify the paths and options passed to initdb by editing:
 *     /etc/conf.d/postgresql-13
 * 
 * Information on options that can be passed to initdb are found at:
 *     https://www.postgresql.org/docs/13/static/creating-cluster.html
 *     https://www.postgresql.org/docs/13/static/app-initdb.html
 * 
 * PG_INITDB_OPTS is currently set to:
 *     --encoding=UTF8
 * 
 * Configuration files will be installed to:
 *     /etc/postgresql-13/
 * 
 * The database cluster will be created in:
 *     /var/lib/postgresql/13/data
 * 
 * Continuing initialization in 5 seconds (Control-C to cancel) ...
 [ ok ]
 * Creating the data directory ...
 * Initializing the database ...
could not change directory to "/var/calculate/tmp/portage/dev-db/postgresql-13.2/homedir": Отказано в доступе
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locales
  COLLATE:  ru_RU.utf8
  CTYPE:    ru_RU.utf8
  MESSAGES: ru_RU.utf8
  MONETARY: ru_RU.utf8
  NUMERIC:  C
  TIME:     ru_RU.utf8
The default text search configuration will be set to "russian".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/postgresql/13/data ... ok
creating subdirectories ... ok
selecting dynamic shared memory implementation ... posix
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default time zone ... W-SU
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok

initdb: warning: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.

Success. You can now start the database server using:

    /usr/lib64/postgresql-13/bin/pg_ctl -D /var/lib/postgresql/13/data -l logfile start

 * The autovacuum function, which was in contrib, has been moved to the main
 * PostgreSQL functions starting with 8.1, and starting with 8.4 is now enabled
 * by default. You can disable it in the cluster's:
 *     /etc/postgresql-13/postgresql.conf
 * 
 * The PostgreSQL server, by default, will log events to:
 *     /var/lib/postgresql/13/data/postmaster.log
 * 
 * You should use the '/etc/init.d/postgresql-13' script to run PostgreSQL
 * instead of 'pg_ctl'.
 * Конфигурация утилитами Calculate системных настроек postgresql ...
 * Утилиты Calculate изменили файлы:
 *      /var/lib/portage/world

The output above contains the main information.

Start PostgreSQL:

/etc/init.d/postgresql-13 start
postgresql-13 | * /run/postgresql: creating directory
postgresql-13 | * /run/postgresql: correcting owner
postgresql-13 | * Starting PostgreSQL 13 ...                                 [ ok ]

Add the SQL server to autostart:

rc-update add postgresql-13
 * service postgresql-13 added to runlevel default

Configuration with password access

Postgres user configuration

Set a password for the postgres user:

su postgres -c "psql -c '\password'"

Database access configuration

Configure access to the SQL server by allowing only local queries and those from the local network ~192.168.0.0/24~:

/etc/postgresql-13/pg_hba.conf
# TYPE  DATABASE        USER            ADDRESS                 METHOD
# "local" is for Unix domain socket connections only
local   all             all                                     password
# IPv4 local connections:
host    all             all             127.0.0.1/32            password
host    all             all             192.168.0.0/24          password
# IPv6 local connections:
#host   all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local  replication     all                                     trust
#host   replication     all             127.0.0.1/32            trust
#host   replication     all             ::1/128                 trust

Specify IP addresses to be listened to by the PostgreSQL, comma-separated:

/etc/postgresql-13/postgresql.conf
#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------

# - Connection Settings -

listen_addresses = '192.168.0.1,127.0.0.1' # what IP address(es) to listen on;
                                           # comma-separated list of addresses;
                                           # defaults to 'localhost'; use '*' for all
                                           # (change requires restart)

Note

If the server needs to be accessed from all network interfaces, set "*" instead of IPs.

Restart the database server:

/etc/init.d/postgresql-13 restart
postgresql-13 | * Stopping PostgreSQL 13 (this can take up to 92 seconds) ... [ ok ]
postgresql-13 | * /run/postgresql: correcting mode
postgresql-13 | * Starting PostgreSQL 13 ...                                  [ ok ]

Check that PostgreSQL is listening on port 5432:

netstat -an
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN     
tcp        0      0 127.0.0.1:5432          0.0.0.0:*               LISTEN     
tcp        0      0 192.168.0.1:5432        0.0.0.0:*               LISTEN     
tcp6       0      0 :::22                   :::*                    LISTEN     
udp        0      0 127.0.0.1:41006         127.0.0.1:41006         ESTABLISHED
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags       Type       State         I-Node   Path
unix  2      [ ACC ]     STREAM     LISTENING     281718   /run/postgresql/.s.PGSQL.5432

Creating user and database

Create user test and their database dbtest:

createuser -U postgres -P test

createdb -U postgres -O test dbtest

Connecting to database

For test to connect to database dbtest, run:

psql -U test -d dbtest
Password for user test:
psql (13.2)
Type "help" for help

test=> \q

Enabling Peer authentication

Peer authentication is based to getting the client operating system username from the kernel and using it as the authorized database username, with additional username mapping. Peer authentication is supported for local connections only.

Configuring authorization

Comment out all connections to the database, leaving only local connections and switching the authentication method to peer:

/etc/postgresql-13/pg_hba.conf
# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
#host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
#host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     all                                     trust
#host    replication     all             127.0.0.1/32            trust
#host    replication     all             ::1/128                 trust

Reload the PostgreSQL settings:

/etc/init.d/postgresql-13 reload

Creating user and database

Create system user test:

useradd test

Create PostgreSQL user test:

su postgres -c "createuser test"

Note

By default, users that are created do not have the privilege to create databases. To change this behavior, add the --createdb parameter.

Create database testdb for user test:

su postgres -c "createdb -O test testdb"

Connecting to database

For test to connect to database dbtest, run:

psql -d testdb

psql (13.2)
Type "help" for help.

testdb=>

For root to connect to database dbtest~, run the following:

su postgres -c "psql -d testdb"

psql (13.2)
Type "help" for help.

testing=#

Benchmark configuration

When you install PostgreSQL, a basic /etc/postgresql-13/postgresql.conf file is created automatically. Feel free to use third party tools (for example, PGTune) to optimize those.

PGTune calculates PostgreSQL configuration parameters based on the maximum performance for a given hardware configuration. However, please bear in mind that many of the parameters are dependent on the size of the database, the number of clients and the complexity of the queries.