Django

A simple insert query turned into a silent performance killer. Our frontend pings our server every few minutes to track device activity. Each ping attempts to insert a row into a DevicePingDaily table, which has a unique constraint on (device_id, date) to ensure only one record per device per day. In Django, the logic looked like this: try: DevicePingDaily.objects.create(device=device, date=today) except IntegrityError: pass It seemed harmless. But as traffic grew, latency spiked and API timeouts increased. Observability tools quickly pointed to the culprit: ...

In a Django application, fetching the latest record for each group is a common yet challenging task, especially when working with large datasets. Whether you’re building an analytics dashboard or managing grouped data, finding an efficient solution is key. In this blog post, we’ll explore five different approaches to tackle this problem, ranked from least to most effective based on performance and readability, using the following Book model: class Book(models.Model): title = models.CharField(max_length=255) author = models.ForeignKey( Author, on_delete=models.CASCADE, related_name="books" ) genre = models.CharField(max_length=255) published_at = models.DateTimeField() is_featured = models.BooleanField(default=False) Solution 1: Python Max with Prefetch latest_books = [ max(author.books.all(), key=lambda x: x.published_at, default=None) for author in Author.objects.prefetch_related("books") ] Performs heavy computation in Python rather than leveraging the database, which is bad for performance. Also makes two database queries (better solutions do it in one). ...

Preventing downtime during deployments is crucial for maintaining service availability and ensuring a positive user experience. Blue-green deployments have emerged as a popular strategy to achieve this goal. However, they introduce challenges, especially when dealing with database changes. This article delves into what blue-green deployments are, why database changes can be tricky in this context, and how to navigate common change scenarios effectively in Django. Blue-Green Deployments A blue-green deployment is a release management strategy that utilizes two separate production environments called “blue” and “green”. At any given time, only one environment is live, serving all production traffic. Changes are deployed to green, and after thorough testing, traffic is switched over from the blue to green. This approach minimizes downtime and provides a quick rollback option by reverting traffic to blue if issues occur. ...

Background As software engineers, one of the most crucial skills we develop is the ability to search through code efficiently. Whether it’s finding a specific function, understanding how a certain feature is implemented, or tracing a bug, being able to quickly navigate a codebase is essential for productivity. However, many codebases can be complex and sprawling, leading to noisy search results that hinder rather than aid our progress. JetBrains provides a few tools to help you refine your code search and focus on what’s important. ...

Optimizing Django query performance is critical for building performant web applications. Django provides many tools and methods for optimizing database queries in its Database access optimization documentation. In this blog post, we will explore a collection of additional and essential tips I’ve compiled over the years to help you pinpoint and resolve your inefficient Django queries. Kill Long-Running Queries with a Statement Timeout PostgreSQL supports a statement_timeout parameter that allows you to set a maximum time limit per query. This is useful for preventing long-running queries from tying up precious resources and slowing down your application. My team at PixieBrix experienced an incident where a few long-running queries resulted in a full database outage. Setting a statement timeout in your Django settings can help prevent this from happening. ...