London PostgreSQL Meetup

Now Andrew Farries is telling us about how databases are like cities, on the way to talking about expand and contract patterns for database schema changes

And it's happening... Chris Ellis is giving the first talk of this evening's Meetup - Fun with UUIDs

Today is the day! For anyone interested in PostgreSQL and near London. The London PostgreSQL meetup is holding an event on: PostgreSQL Schema Migrations & Data Modeling. Hosted at The Star Of Kings, near St Pancras, starting at 18:30. Andrew Farries of Xata is presenting Postgres Schema Migrations Using The Expand/Contract Pattern Learn how to do Postgres schema changes without breaking dependent applications by leveraging the expand/contract pattern. pgroll is a new open-source migration tool for Postgres that keeps multiple versions of a schema live during a migration, helping you roll out database schema changes without downtime. Postgres schema changes often pose significant challenges to developers, particularly when striving for zero downtime migrations. Chris Ellis of Nexteam is presenting Fun With UUIDs UUIDs have a bad reputation, mostly based on randomly allocated UUIDs effect on indexes. But UUIDs also give us 16 bytes of space to play with, which can be to our advantage. We can use the space of UUIDs to structure and encode data into our identifiers. This can be really useful for multi-tenant applications, for sharding or paritioning. UUIDs can also help improve you web app security, by not leaking sequentially allocated ids. It should be an interesting evening for both application developers and DBAs. Since you read this far, there will also be some free drinks and food provided. More information and signup: https://lnkd.in/e7bMs4Bn Look forward to seeing you all.

At a loose end for tomorrow evening? Interested in PostgreSQL? Then come along to the London PostgreSQL meetup. Tuesday 29th July, 18:30 at The Star Of Kings, near St Pancras. We've got some interesting talks on how to manage PostgreSQL database schemas, using quite an interesting approach and an Open Source tool that Xata has built. We'll also have a short talk on UUIDs, covering the issues of using them for primary keys and the fun things you can do with them. More & Signup: https://lnkd.in/e7bMs4Bn

Are you wondering what you'll be doing in a week's time? If you're in London and interested in Postgres, managing change in relational database schemas, or both, you could be on your way to our second Meetup event of the year.

Upcoming Events In a couple of weeks we've got the second London PostgreSQL Meetup event happening: PostgreSQL Schema Migrations & Data Modeling. This is taking place on Tuesday 29th July 2025 at The Star Of Kings (N1 0AX) near St Pancras. Where we have Andrew Farries of Xata, presenting: Postgres Schema Migrations Using The Expand/Contract Pattern. This will be an interesting talk for application developers and DBAs alike, covering an interesting approach to schema management and introducing pgroll, an open source tool for schema management. Find out more and sign up: https://lnkd.in/e7bMs4Bn At the end of summer, PGDay UK is back for 2025, on September 9th at Cavendish Conference Centre, London (near Oxford Circus). It promises to be an exciting event again and we hope to make it bigger and better than last year. The schedule has just been announced and the CFP team did a great job in selecting a range of talks, there really is something for everyone interested in PostgreSQL. There has never been a better time to get your ticket now. See the schedule and get your ticket: https://2025.pgday.uk/ Shortly after PGDay UK why not hop on the Eurostar to Rotterdam and experience PGDay Lowlands, on September 12th at Blijdorp Zoo, Rotterdam, Netherlands. This is the second PGDay Lowlands after their excellent first event last year. They have an innovative schedule, with a mix of talks, lightning talks and debates. It promises to be another great event, in a venue which even has actual Elephants :) Take a look and go along too: https://2025.pgday.nl/

We're excited to be back for our 2nd meet up of 2025 on Tuesday 29th July, 18:30 at The Star Of Kings (N1 0AX). This event will be covering PostgreSQL schema migrations and management, a topic I'm sure a number of application developers and PostgreSQL DBAs can resonate with. We'll provide some free drinks and snacks for those attending, starting from 18:30, aiming to get our main talk underway shortly after starting. Find out more and register at: https://lnkd.in/e7bMs4Bn Main Talk: Postgres Schema Migrations Using The Expand/Contract Pattern Learn how to do Postgres schema changes without breaking dependent applications by leveraging the expand/contract pattern. pgroll is a new open-source migration tool for Postgres that keeps multiple versions of a schema live during a migration, helping you roll out database schema changes without downtime. Postgres schema changes often pose significant challenges to developers, particularly when striving for zero downtime migrations. There are many things that can go wrong:    Schema changes breaking client applications    Unexpected table locking causing downtime    Human mistakes causing data loss This talk presents a new approach to schema changes using an ‘expand/contract’ pattern where multiple versions of a database schema are maintained during the migration, allowing old and new versions of client applications to run side-by-side during an application rollout. Each version of the application sees the version of the database schema with which it is designed to work. The talk covers the ideas behind this approach, and the challenges to be overcome such as: The use of Postgres views to present multiple versions of an underlying table. Backfilling data between old and new schema versions. Techniques to avoid unexpected table locking during migrations. Finally we introduce pgroll, an open-source tool that puts these ideas into practice and we show how it can be used to facilitate safe application rollouts across database schema changes. Presented By: Andrew Farries of Xata Andrew has over 10 years experience building developer tools, with a particular focus on database tools in cloud-native environments. He currently works at Xata, building a serverless data platform powered by Postgres.