PostgreSQL Usergroup NL Winter-edition meetup 2026

Sessions

Just enough Postgres compatibility to keep your sanity
By Jelte Fennema-Nio – MotherDuck

Postgres has become the most popular database, which is why many other databases claim to be “Postgres compatible”. But the hard truth is: only PostgreSQL is fully “Postgres compatible”. Everyone else is just a clever impostor trying to fool most users. And given enough users, there is always one who finds a new compatibility bug.

Jelte has spent years perfecting this art of deception, having implemented the Postgres protocol twice: first as a maintainer of the PgBouncer connection pooler, and then while building the “Postgres Endpoint” for MotherDuck (a data warehouse based on DuckDB). In this talk, he shares the interesting, funny and often horrifying lessons he has learned about building Postgres-compatible servers.

What you will learn in this talk:

• How to build your own “Postgres compatible” database with just a few lines of Go code
• A deep understanding of the Postgres protocol
• Why the line between the protocol and the SQL dialect is rather blurry
• How clients and ORMs (mis)use the system catalogs in pg_catalog and information_schema
• When to say: “This is enough!”

About Jelte:
Jelte Fennema-Nio is a PgBouncer maintainer and Postgres major contributor. He currently works at MotherDuck, a data warehouse company built on DuckDB, where he combines Postgres and DuckDB in various ways. Before that, he spent five years at Microsoft working on Citus, Postgres and PgBouncer.

Disaggregating PostgreSQL Storage from Compute with Azure HorizonDB
By Nils Dijk

Building a completely new storage layer for a transactional database is not something many people would advise you to do; quite the contrary. However, when the upsides are big, it is well worth the effort. With a mature environment like Azure and a team with decades of experience in database internals, a seemingly impossible task becomes doable. In this talk, we walk through the design of HorizonDB, compare it to the usual suspects and highlight the trade-offs we made. We will touch on Aurora, Socrates, Neon and many Postgres internals, but no prior experience is required. As a bonus, we discuss how to secure untrusted C code in a multi-tenant enterprise environment without reimplementing Postgres’ redo subsystem.

About Nils:
Nils Dijk is a Principal Software Engineer currently enjoying a multi-retirement. Before stepping away, he was part of the team behind Azure HorizonDB, disaggregating storage from compute for PostgreSQL. Although he now works exclusively on Postgres-related projects, he started his career in the mid-2010s and was, as a side effect, clouded by the NoSQL philosophy. That came to an abrupt end while he was working on the dispatch systems at Uber: although the system of record was NoSQL-based, the actual business value came from the SQL layer built on top of it. With that experience, he set out to scale SQL databases without giving up their business benefits. This led him to Citus Data, where he worked on everything from the query planner to cluster management, fulfilling the vision of a seamlessly scaling SQL database.

Lightning Talks

What are Lightning Talks?

A lightning talk is a short presentation given at a conference or meetup. Unlike regular presentations, lightning talks last only a few minutes, and several are usually given in quick succession by different speakers. Within a single slot, anyone can share their vision, present a short topic or ask the audience for input.

At the PostgreSQL Usergroup NL meetups, lightning talks offer participants an accessible stage to share their experience and knowledge.

Would you like to submit a lightning talk? Do you have a short topic, or something to share about PostgreSQL or a related area? Send us an email with your suggestion, your topic, or simply your name with a request for a time slot, and we will schedule you in the lightning talks! You can also add your name to the list on the evening itself.

Submit Lightning Talk

Location

The meetup will be held at the JetBrains office in Amsterdam:

The address is:

Terrace Tower, Gelrestraat 16
1079 MZ Amsterdam
The Netherlands

Getting there:

The JetBrains office is easily accessible. By car: the office is located opposite the RAI, take exit S109 from the A10 ring road.

There is ample parking around the RAI.

Coming by public transport? Take the train or metro to Amsterdam RAI station.

Register for the Meetup