One Database Transaction Too Many
A story about how I ended up sending hundreds of users messages saying they got paid when they didn't! In the process we've learned a valuable lesson about nested transactions and Django signals.
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Practical SQL for Data Analysis
Pandas is by far the most popular tool for data analysis. It's packed with useful features, it's battle tested and widely accepted. However, pandas comes at a cost which is often overlooked. SQL databases has been around since the 1970s. They contain many features that most developers never heard of, and I want to bring some of them to light.
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Exciting New Features in Django 3.2
Django 3.2 is just around the corner and it's packed with new features. Django versions are usually not that exciting (it's a good thing!), but this time many features were added to the ORM, so I find it especially interesting!
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The Unexpected Find That Freed 20GB of Unused Index Space
In this article I describe the process we took to identify potential free space, and one surprising find that helped up clear up ~10GB of unused indexed values!
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Re-Introducing Hash Indexes in PostgreSQL
There is a type of index you are probably not using, and may have never even heard of. It is wildly unpopular, and until a few PostgreSQL versions ago it was highly discouraged and borderline unusable, but under some circumstances it can out-perform even a B-Tree index.
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Exhaustiveness Checking with Mypy
What if mypy could warn you about possible problems at "compile time"? In this article I share a little trick to get mypy to fail when a value in an enumeration type is left unhandled.
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The Surprising Impact of Medium-Size Texts on PostgreSQL Performance
Any database schema is likely to have plenty of text fields. In this article I demonstrate the surprising impact of medium-size texts on query performance.
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Simple Anomaly Detection Using Plain SQL
Many developers think that having a critical bug in their code is the worse thing that can happen. Well, there is something much worst than that: Having a critical bug in your code and not knowing about it! Using some high school level statistics and a fair knowledge of SQL, I implemented a very simple anomaly detection system.
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Some SQL Tricks of an Application DBA
Some tips and misconceptions about database development I gathered along the way.
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Stop Using datetime.now!
If you ever had a test that one day just started to fail, unprovoked, or a test that fails once every blue moon for no apparent reason, it's possible your code is relying on something that is not deterministic. In this article I describe a practical approach to dependency injection in Python that when used correctly, can eliminate nondeterminism and make your code easier to maintain and to test.
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