PostgreSQL 11:INITDB

Hello,

So here I am writing another article about PostgreSQL. If you do not have this database installed and would like to learn and try about this database engine, check out my last post about installation: https://www.techdatabasket.com/postgresql-11-installation-on-centos-el7-x86_64/

After the installation we have to start the initdb file that creates a new PostgreSQL database cluster. This file can be invoked both through the command :


/usr/pgsql-11/bin/initdb

Where in this case /usr/pgsql-11/bin is the directory where the software is installed by default or you can also invoke this utility using this command:


/usr/pgsql-11/bin/pg_ctl initdb

Nevertheless the output, it will be something like this:

-bash-4.2$  /usr/pgsql-11/bin/initdb
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 locale "en_US.UTF-8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/pgsql/11/data … ok
creating subdirectories … ok
selecting default max_connections … 100
selecting default shared_buffers … 128MB
selecting default timezone … UTC
selecting dynamic shared memory implementation … posix
creating configuration files … ok
running bootstrap script … ok
performing post-bootstrap initialization … ok
syncing data to disk … ok

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/pgsql-11/bin/pg_ctl -D /var/lib/pgsql/11/data -l logfile start

However, at this point if you try to connect directly to the psql console you will receive this error:


-bash-4.2$ psql -l
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Then, to be able to connect properly to this console you must have to start the server:


-bash-4.2$ /usr/pgsql-11/bin/pg_ctl -D /var/lib/pgsql/11/data -l logfile start
waiting for server to start…. done
server started

And finally you can connect to the cluster console and list all the existing databases:


bash-4.2$ psql -l
List of databases
Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
|          |          |             |             | postgres=CTc/postgres
template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
|          |          |             |             | postgres=CTc/postgres
(3 rows)

-bash-4.2$

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