PostgreSQL

Table of Contents

• PostgreSQL
  • Repository Manager
  • File Locations
  • The pg_hba.conf File
  • The postgresql.conf File
    • Basic Commands
      • Connecting to PostgreSQL
      • PSQL

Repository Manager

The Repository installer and manager allows you to install your selected version of the PostgreSQL Repository.

It can be access via the Pg Installer tab as shown below:

You can also use the manager to install and update packages as well.

As certain packages require EPEL for CentOS, the EPEL repository is installed as well when installing on CentOS.

File Locations

The PostgreSQL config direcotry is located at:

/etc/postgresql/15/main

The pg_hba.conf File

On installation via the Wizard, PostgreSQL is configured for use with SSL and uses scram-sha-256 authentication for all users and databases.

local   all all                                 trust
host    all all 127.0.0.1       255.255.255.255 trust
host    all all 0.0.0.0/0                       scram-sha-256
host    all all ::1/128                         scram-sha-256
hostssl all all 127.0.0.1       255.255.255.255 scram-sha-256
hostssl all all 0.0.0.0/0                       scram-sha-256
hostssl all all ::1/128                         scram-sha-256

The postgresql.conf File

On installation via the Wizard, PostgreSQL is configured to accept connections on all interfaces as well as SSL connections.

#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------

# - Connection Settings -

listen_addresses = '*'
)


# - SSL -

ssl = on

Above are excepts.

On installation, the native PostgreSQL Database Server module is also activated.

It is located under Servers > PostgreSQL Database Server

Basic Commands

Below are some basic PSQL commands.

PostgreSQL documentation, both from PostgreSQL.org and other sources, is extensive.

https://www.postgresql.org/docs/current/tutorial.html

https://www.postgresqltutorial.com/

Connecting to PostgreSQL

There are a number of options for viewing your PostgreSQL data.

1. PSQL command line
2. PgAdmin
3. Control Panel

PSQL

Connect via SSH and su to postgres

root@demo:# su - postgres

Start psql

postgres@demo:~$ psql
psql (15.3 (Ubuntu 15.3-1.pgdg22.04+1))
Type "help" for help.

List all databases using the ‘\l’ command

postgres=# \l
                                              List of databases
    Name    |  Owner   | Encoding | Collate |  Ctype  | ICU Locale | Locale Provider |   Access privileges
------------+----------+----------+---------+---------+------------+-----------------+-----------------------
 geostore   | postgres | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            |
 geodb      | geouser  | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            |
 postgisftw | pgis     | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            |
 postgres   | postgres | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            |
 template0  | postgres | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            | =c/postgres          +
            |          |          |         |         |            |                 | postgres=CTc/postgres
 template1  | postgres | UTF8     | C.UTF-8 | C.UTF-8 |            | libc            | =c/postgres          +
            |          |          |         |         |            |                 | postgres=CTc/postgres
(5 rows)

Connect to target database (in this case, postgisftw) using the ‘\c’ command

postgres=# \c postgisftw
You are now connected to database "postgisftw" as user "postgres".

List tables in database using the ‘\dt’ command

 postgisftw=# \dt
               List of relations
 Schema |       Name        | Type  |  Owner
--------+-------------------+-------+----------
 public | configuration     | table | pgis
 public | countries         | table | pgis
 public | pointsofinterest  | table | pgis
 public | spatial_ref_sys   | table | postgres
 public | ways              | table | pgis
 public | ways_vertices_pgr | table | pgis
(6 rows)

Select country name from the countries table, limited to 10:

postgisftw=# select name from countries limit 10;
           name
--------------------------
 Zimbabwe
 Zambia
 Montserrat
 Yemen
 Vanuatu
 Uruguay
 Vietnam
 Micronesia
 Venezuela
 Vatican
 (10 rows)

Select country name from the countries table, limited to 10, sorting acecnded:

postgisftw=# select name from countries order by name ASC limit 10;
       name
-------------------
 Afghanistan
 Albania
 Algeria
 American Samoa
 Andorra
 Angola
 Anguilla
 Antarctica
 Antigua and Barb.
 Argentina
(10 rows)

postgisftw=#