Postgresql on Caktus Group

Avoiding Timezone Traps: Correctly Extracting Date/Time Subfields in Django with PostgreSQL

Mon, 16 Jun 2025 19:00:00 +0000

Working with timezones can sometimes lead to confusing results, especially when combining Django's ORM, raw SQL for performance (like in PostgreSQL materialized views), and specific timezone requirements. I recently had an issue while aggregating traffic stop data by year, where all yearly calculations needed to reflect the 'America/New_York' (EST/EDT) timezone, even though our original data contained timestamp with time zone fields. We were using django-pgviews-redux to manage materialized views, and I mistakenly attempted to apply timezone logic to a date field that had no time or timezone information.

Tips for Tracking Django Model Changes with django-pghistory

Mon, 07 Apr 2025 10:00:00 +0000

Django and its admin interface are a big part of why Caktus uses Django, but the admin's ability to log database changes is limited. For example, it shows only changes made via the Django admin, not via other parts of the site.

How to Use regexp_matches and regexp_match in PostgreSQL

Wed, 19 Mar 2025 08:00:00 +0000

Introduction

regexp_matches() and regexp_match() are two similar string functions that support regular expression matching directly in the PostgreSQL database. regexp_matches() was added in PostgreSQL 8.3, and regexp_match() was added in PostgreSQL 10 (keep reading to see how ChatGPT struggled to answer this question).

Getting Started with Dagster

Mon, 09 Dec 2024 23:00:00 +0000

Recently, Caktus has been using Tailscale to manage VPN connections between Android tablets and a central server. We wanted to report on the devices connected to the network using the Tailscale API. While we could use tools like Celery to fetch data from the API and load it into a database—given its widespread use in the Django ecosystem—we also wanted to explore other options.

How to Use Kubernetes on Azure for Cloud Computing

Tue, 28 Apr 2020 18:41:03 +0000

For the Review, Appraisal, and Triage of Mail (RATOM) project, funded by the Andrew W. Mellon Foundation, we were tasked with deploying to a Microsoft Azure environment. More details about the project are in our first blog post in this Learn With Us blog series. Caktus has experience with Amazon Web Services (AWS) and Google Cloud, but we hadn't had the opportunity to use Azure yet, so we looked forward to the opportunity to use that environment and document our experience. The entire deployment process is available on GitHub as a reference under the StateArchivesOfNorthCarolina/ratom-deploy repository.

Postgres Present and Future (PyCon 2016 Must-See Talk: 6/6)

Thu, 18 Aug 2016 12:00:00 +0000

Part six of six in our annual PyCon Must-See Series, a weekly highlight of talks our staff especially loved at PyCon. With so many fantastic talks, it’s hard to know where to start, so here’s our short list.

Query Expressions are Amazing

Mon, 20 Jun 2016 11:30:00 +0000

The Django 1.8 release added support for complex query expressions. The documentation has some nice examples but they don't do justice to how crazy awesome these are. In this post, we will go through some additional examples of how to leverage these expressions.

OpenBlock Geocoder, Part 1: Data Model and Geocoding

Mon, 12 Dec 2011 16:17:20 +0000

As Tobias mentioned in Scraping Data and Web Standards, Caktus is collaborating with the UNC School of Journalism to help develop Open Rural (the code is on GitHub). Open Rural hopes to help rural newspapers in North Carolina leverage OpenBlock. This blog post is the first of several covering the internals of OpenBlock and, specifically, the geocoder.

Basic Django deployment with virtualenv, fabric, pip and rsync

Fri, 23 Apr 2010 00:46:37 +0000

Deployment is usually a tedious process with lots of tinkering until everything is setup just right. We deploy quite a few Django sites on a regular basis here at Caktus and still do tinkering, but we've attempted to functionalize some of the core tasks to ease the process. I've put together a basic example that outlines local and remote environment setup. This is a simplified example and just one of many ways to deploy a Django project (I learned a lot from Jacob Kaplan-Moss' django-deployment-workshop), so I encourage you to browse around the Django community to learn more. The entire source for this example project can be found in the caktus-deployment Bitbucket repository.

Setting PostgreSQL's SHMMAX in Mac OS X 10.5 (Leopard)

Thu, 13 Aug 2009 11:46:08 +0000

If you've ever tried to increase the shared_buffers setting in your postgresql.conf to a value that exceeds the amount of shared memory supported by your operating system kernel, then you'll see an error message like this:

Explicit Table Locking with PostgreSQL and Django

Tue, 26 May 2009 18:59:10 +0000

By default, Django doesn't do explicit table locking. This is OK for most read-heavy scenarios, but sometimes you need guaranteed, exclusive access to the data. Caktus uses PostgreSQL in most of our production environments, so we can use the various lock modes it provides to control concurrent access to the data. Once we obtain a lock in PostgreSQL, it is held for the remainder of the current transaction. Django provides transaction management, so all we need to do is execute a SQL LOCK statement within a transaction, and Django and PostgreSQL will handle the rest.

Why Caktus Uses Django

Tue, 13 Jan 2009 15:45:31 +0000

Here at Caktus, we use the popular Django web framework for a lot of our custom web application development. We don't use Django simply because it's popular, easy to learn, or happened to be the first thing we found. We've written web apps in PHP, Java, and Ruby on Rails--all before we discovered Django--but were never quite satisfied. Following are just a few of the reasons that we both enjoy working with Django and believe it gives you (the client) the best end-product.

minibooks: Small Business Bookkeeping

Wed, 07 Jan 2009 15:49:06 +0000

Caktus released minibooks (open-sourced under the AGPL) as a bookkeeping package for small tech agencies. Boasting a double-entry accounting system, customer relationship management (CRM) and transaction reconciliation, minibooks provides a clean, multiuser web-based interface to manage simple accounting needs for small businesses.

Asterisk CDR & Django integration with ODBC

Mon, 13 Oct 2008 14:58:09 +0000

Tobias already mentioned how Caktus uses Asterisk as our PBX. He also mentioned how we tested various frontends both for managing the asterisk configuration and interacting with asterisk to, for example, check our voicemail. We were inticed by some of the client management solutions that we could plumb up with asterisk. Caktus has a loose administration structure, which allows us to be flexible and not have levels of managers between clients and coders. But, this flexiblility can leave loose ends unchecked when the person in charge of a project is distracted for a day or two. We saw this as an opportunity where Caktus could add a level of group accountability and use some neat technology. We also wanted a tool that would integrate well with our current homegrown DjangoERP/CRM as well as Trac, our prefered tool for project management. So, we decided to write some sweet code.

Database Explained for the Business Professional

Fri, 22 Feb 2008 08:23:58 +0000

One problem with marketing is that it introduces pseudo-false concepts, arbitrarily divorces necessarily wed ones, and leaves out all the gory details. We recently had a client ask us,