TIL on staticnotes.org

TIL how to set up multiple SSH keys (for multiple Github accounts)

Fri, 28 Nov 2025 16:20:00 +0000

Setting up SSH keys is one of these things I need to do every couple of months. Inevitably, I don’t remember how to do it and then follow some tutorial, e.g. the Github Docs . It kind of always works but I haven’t fully internalized how to properly manage those different SSH keys.

Disclaimer: This learning was provoked by setting up multiple SSH keys for different Github accounts (I know how to do that) and then being able to git clone {private-repository} a private repository with the correct ssh key (I didn’t know how to do that). An example use case could be a personal and professional Github account that don’t have access to the same private repositories. So ideally when we git clone we want to automatically pick the right ssh key.

TIL how to re-run only failed tests

Fri, 21 Nov 2025 13:00:00 +0000

This is a super small thing I stumbled over. When I implement a new feature, there is inevitably a step where I go through the failing pytest tests and fix or clarify them.

Unless I use an IDE, my work loop is like this:

Make code change
Run python -m pytest
Check which tests are failing.
Go back to 1.

Now, 2. runs all tests which can take quite some time. There is always the option to run a specific test only, but multiple failing tests can be scattered across different files.

TIL how to investigate missing data easily with DuckDB

Fri, 16 May 2025 14:00:00 +0000

In data engineering pipelines we commonly store output data in S3 buckets at various stages. In this particular case we stored the input data received from customers as csv files in the S3 bucket s3://customer-ingested/customerA.csv and after some transformations we stored the transformed data as csv files in another S3 bucket s3://customer-transformed/customerA.csv.

Problem

For some of the customers the csv file was missing in the first bucket customer-ingested while we were sure that all customers had a file in customer-transformed. However, there was a legit reason why the file could be missing which was that in the application the customer had a state of is_deactivated = True.

TIL that DuckDB now supports Avro files

Wed, 12 Mar 2025 16:00:00 +0000

In the data engineering pipelines of my current company we use two main file formats:

Parquet files for analytical workloads (columnar-storage)
Avro files for transactional / event-based messages (row-storage)

In Querying remote S3 files I wrote about how I use DuckDB to query parquet files stored in S3. Recently, I noticed that DuckDB started supporting reading of Avro files in the same way.

TIL how to fix a broken Joplin sync

Mon, 17 Feb 2025 00:00:00 +0000

I use Joplin for all my note-taking as it’s open-source, markdown-based, and has decent Desktop and Android apps. I use note encryption and sync my notes via WebDAV with my remote Nextcloud instance.

Problem

After not syncing my notes for several weeks, I encountered a couple of errors both on my Desktop app and on my Android app. I don’t have access to the error message anymore, but the errors referred to files and file IDs that caused inconsistencies on the remote server, e.g. broken references:

TIL how to debug a broken nextcloud login (again)

Sun, 16 Feb 2025 00:00:00 +0000

The symptoms of this problem were the same as the ones I described in TIL how to debug a broken nextcloud login .

Problem

Phone and Mac apps stopped syncing data with the Nextcloud instance. In my browser I could access the login page, but after entering the details I was being sent back to the same login page without any error message.

Investigation

Last time the issue was caused by excessive logging. However, I reduced the loglevel in the nextcloud config, so this was not the issue here. I am no expert in web admin, PHP, or nextcloud, so I used Claude 3.5 to pair on debugging:

TIL (from Claude) how to create separate RSS feeds for my hugo blog

Thu, 03 Oct 2024 00:00:00 +0000

I really like the idea of providing different content types of my blog in separate RSS feeds. For example a blog could have:

essays
today-I-learned posts
link-list or bloglink posts
short social media style posts
etc.

Providing different RSS feeds for them allows my readers to subscribe to all or a subset of these, depending on their interest. I am using hugo, as the static site generator for this website. Setting up these different feeds for a framework that I am only partially familar with is a great use-case to work with an LLM.

TIL about the QUALIFY statement in SQL

Mon, 16 Sep 2024 00:00:00 +0000

Today I came across the QUALIFY clause which is supported in some SQL dialects. It’s not part of the SQL standard but supported by main analytical databases like BigQuery, Snowflake, Oracle, Databricks, DuckDB, etc. It’s part of Snowflake’s dialect which is the data warehouse that I use at work. The QUALIFY statement lets me filter the result of a query based on the result of a window function.

TIL about just and justfiles

Fri, 13 Sep 2024 00:00:00 +0000

just is just a command runner that I recently started using to define aliases for commands in my projects, e.g. build, test, or deploy commands.

Installation

just can be installed via homebrew:

brew install just

Example

I want to create alias commands for my dbt project to build my dbt models in production vs. development environments. At the moment, I need to run the commands:

TIL to create continuously numbered lists with content between items

Wed, 21 Aug 2024 00:00:00 +0000

When writing notes in markdown I commonly encounter the problem that I want to create an automatically numbered list with content between the items. However, this messes up the numbering as it creates two separate numbered lists, e.g.

My first point
My second point

code block or image

My third point
My fourth point

The solution to this is embarrassingly obvious once you know it. Just move the image or code block one level down by indenting it with four spaces. This keeps the list intact.

TIL how to set a lower threshold on a column in SQL

Wed, 07 Aug 2024 00:00:00 +0000

For the last couple of months I came across multiple instances where I wanted to write an SQL query to lower threshold all the values in a particular column in one of our Snowflake tables.

I used quite clunky workarounds to do that. It turns out you can use the SQL functions GREATEST or LEAST for it.

Example

I am creating a temporary table in the first CTE with a column DATA_COLUMN that has positive and negative numbers.

TIL how to set up a local LLM as an assistant in VSCode

Wed, 10 Jan 2024 00:00:00 +0000

I am still trying to get used to the fact that the product of state-of-the-art AI companies is essentially a GB-sized CSV file and some instructions about the network architecture to perform the inference. Recently released “open source” models of medium-size are showing quite decent performance on benchmarks , so I was interested how easy it would be to set them up locally to help me with coding tasks in VSCode. Short answer: very easy.

TIL how to generate a dbt staging model description from snowflake table

Wed, 04 Oct 2023 00:00:00 +0000

In my team we use dbt to create, document, and test data models in our data warehouse, snowflake . We use different layers of models that start from the raw data and in each layer increase complexity and specialization for the target use case:

TIL how to use snowflake's VALUES sub-clause

Tue, 03 Oct 2023 00:00:00 +0000

Today I found out about the useful VALUES() sub-clause in snowflake that allows you to dynamically generate a fixed, known set of rows inside your query.

Problem

I had a table exchange_rates of EUR-currency pairs with their corresponding exchange rates

date	base_currency	target_currency	exchange_rate
2023-10-03	‘EUR’	‘GBP’	0.87
2023-10-03	‘EUR’	‘USD’	1.05
2023-10-03	‘EUR’	‘JPY’	155.95

that I wanted to join with a table transactions which contained transaction prices in different currencies:

TIL how to debug a broken nextcloud login

Sat, 19 Aug 2023 00:00:00 +0000

For the past month I was confronted with the downside of self-hosting. I use Nextcloud for me and my partner’s calendar, online file storage, and notes syncing. I host Nextcloud on a small 7EUR/month Hetzner VPC. Unfortunately, about a month ago it stopped working. Phone apps would not sync the calendar, Joplin notes were not synced across devices and I could not log into my Nextcloud account. I avoided trying to fix the issue quickly, because I know from experience that a short bug investigation in a self-hosting project can quickly spiral into a weekend long endeavour. Fortunately, I had some time this morning and I could fix the issue quickly. Leaving this here for future reference.