How to run PostgreSQL on Docker

Postgres on Docker 

Postgres is most advanced object relational database management system(ORDBMS). Postgres implements majority of SQL:2011 standard. It's ACID compliant and It avoids locking issues using multiversion concurrency control. So today we are going to run Postgres on Docker.

To start with Postgres we first need to pull the image from DockerHub. DockerHub is image repository for all images. Let's run the below command and pull the image:

docker pull postgres

Using default tag: latest

latest: Pulling from library/postgres

a9eb63951c1c: Pull complete 

b192c7f382df: Pull complete 

e7ce3f587986: Pull complete 

4098744a1414: Pull complete 

4c98d6f3399d: Pull complete 

65e57fefc38a: Pull complete 

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de6b20f44659: Pull complete 

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7f74f4b0e936: Pull complete 

144c847b11fb: Pull complete 

cf0afd1be009: Pull complete 

fe0c14991327: Pull complete 

Now let's check that we have downloaded the image.

docker images

REPOSITORY        TAG       IMAGE ID       CREATED       SIZE

postgres          latest    83ce63c594ee   5 days ago    355MB

Let's run the image and start a container.

docker run --name test -e POSTGRES_PASSWORD=Test@123 -d postgres

Just run the docker ps command to check if container is running

docker ps

CONTAINER ID   IMAGE      COMMAND                  CREATED         STATUS   

83ec4a222   postgres   "docker-entrypoint.s…"   2 minutes ago   Up 

Let's enter in bash shell of container by running below command

docker exec -it 83ec4a222 bash

root@83ec4a222:/# 

Connect to Postgres now:

psql -h localhost -p 5432 -U postgres -w

psql (14.0 (Debian 14.0-1.pgdg110+1))

Type "help" for help.

You are connected to Postgres now. Lets' create some tables and execute some queries.

postgres=# \l

                                 List of databases

   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges   

-----------+----------+----------+------------+------------+-----------------------

 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 

 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +

           |          |          |            |            | postgres=CTc/postgres

 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +

           |          |          |            |            | postgres=CTc/postgres

(3 rows)

postgres=# 

Let's check the current database name by running below command.

postgres=# select current_database();

 current_database 

------------------

 postgres

(1 row)

So current database is Postgres. We'll check now how many databases are there on the system.

postgres=# select datname from pg_catalog.pg_database;

  datname  

-----------

 postgres

 template1

 template0

(3 rows)

There are total 3 databases on system.

You can check all tables on a database by querying information schema.

postgres=# select table_name from information_schema.tables limit 10;

      table_name       

-----------------------

 pg_statistic

 pg_type

 pg_foreign_table

 pg_authid

 pg_shadow

 pg_statistic_ext_data

 pg_roles

 pg_settings

 pg_file_settings

 pg_hba_file_rules

(10 rows)

We can do a lot more than this on Postgres this was just a small part about Postgres. We can get all information about all tables and databases just by using information schema. Docker can be very useful in this case when we don't want to install it on system and want to run Postgres inside container and can leverage the power of Docker.

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