Johnny Metz
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Overview
About Me Full Stack Software Engineer located in San Francisco, CA. I specialize in web development with Python, Django, React, Docker, Kubernetes and AWS.Popular YouTube Videos Side Projects Notifire.
News
Django Custom Managers Are Silently Leaking Data
Django custom managers are a common way to exclude rows by default, such as inactive or soft-deleted rows. However, they don't run everywhere you'd expect, which leads to unintended data exposure. This post covers where that happens and how to fix it.The
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Avoiding Duplicate Objects in Django Querysets
When filtering Django querysets across relationships, you can easily end up with duplicate objects in your results. This is a common gotcha that happens with both one-to-many (1:N) and many-to-many (N:N) relationships. Let's explore why this happens and t
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Speed Up Django Queries with values() over only()
If your Django queries feel slow, the problem might not be your database - it might be your ORM. Recently, I was working with a query that took 25 seconds to run through the Django ORM, but the underlying SQL completed in just 2 seconds. With a single cha
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Avoiding PostgreSQL Pitfalls: The Hidden Cost of Failing Inserts
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
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Zero Downtime Django Deployments with Multistep Database Changes
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
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