Software engineering facts, information, and skills tagged as PostgreSQL

Search database with regular expression in Django

Varghese Chacko 1 year, 2 months ago

Regex and iregex are  the two field lookups that enable us to search database with regular expressions. regex is case-sensitive where as iregexis case-insensitive.

Export results of SQLs from Heroku using Data Clips

Varghese Chacko 1 year, 3 months ago

Heroku comes with nice database backup tools, both commandline and web based. But how to export results of an SQL query?

Concatenate two columns in results of SQL query in PostgreSQL

Varghese Chacko 1 year, 3 months ago

Very often, you will have the requirement to concatenate two columns in a table, on the fly in SELECT SQL. For example, first name and last name needed to be combined at username. The + operator is available in MicroSoft's database servers, but it is not part of PostgreSQL or SQL standard. PostgreSQL very well support string concatenation in SQL results. Let us assume that we have a table like

PG::Error (FATAL: too many connections for role "xxxxxxx")

Varghese Chacko 1 year, 3 months ago

PostgreSQL could be configured to limit number of simultaneous connections to the database. The heroku comes with plans having connection limits. The 'Hopby' plans comes with 20 connections where as standard plans comes startings with 120 conection. When we start developing and testing, especially automated testings, the hobby plans raise error PG::Error (FATAL: too many connections for role "xxxxxxx"). If we check the connections with heroku cli, we get

Create a database, create a user and grant privileges in PostgreSQL Databas...

Varghese Chacko 1 year, 3 months ago

To create a database, create a user and grant privileges to the user on command line is often a requirement only when a new project is initialized. The process is described in few simple steps. The local system has a super user named 'postgres' in the Linux, who can login to local database without password. The operating System - Linux - does have the user postgres, but the password is unknown. The solution is to login to the system as a user with super user privileges. Then use sudo and su commands to login as postgresql

How to install and do minimum configuration of Mezzanine

Varghese Chacko 1 year, 3 months ago

This article assumes that you are familiar with installing and configuring Django. Mezzanine ia a Django project at It is licenced under BSD. It can be used, modified, and redistributed commercially. There is a demo available at

How this site is built?

Varghese Chacko 1 year, 3 months ago

“We need a website with blog!” That was the call. Thank you for being here. This is the website site for Atemon Technology Consultants LLP. A software engineering firm needs a website. First version was a plain HTML single page website with no dynamic content. Now we are going to take the company to next level and we wanted a better website with a blog to make it a place that share knowledge. We hope we will keep this blog a technical one.