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Tomas Vondra: So why don't we pick the optimal query plan?
Last week I posted about how we often don’t pick the optimal plan. I got asked about difficulties when trying to reproduce my results, so I’ll address that first (I forgot to mention a couple details). I also got questions about how to best spot this issue, and ways to mitigate this. I’ll discuss that too, although I don’t have any great solutions, but I’ll briefly discuss a couple possible planner/executor improvements that might allow handling this better.
Andreas 'ads' Scherbaum: Josef Machytka
Ian Barwick: PgPedia Week, 2025-07-06
PostgreSQL 19 development is now officially under way, so from now on any new features will be committed to that version. Any significant PostgreSQL 18 changes (e.g. reversions or substantial changes to already committed features) will be noted here separately (there were none this week).
PostgreSQL 19 changes this weekThe first round of new PostgreSQL 19 features is here:
Jan Kristof Nidzwetzki: Analyzing PostgreSQL Performance Using Flame Graphs
A flame graph is a graphical representation that helps to quickly understand where a program spends most of its processing time. These graphs are based on sampled information collected by a profiler while the observed software is running. At regular intervals, the profiler captures and stores the current call stack. A flame graph is then generated from this data to provide a visual representation of the functions in which the software spends most of its processing time. This is useful for understanding the characteristics of a program and for improving its performance.
Chris Ellis: PGDay UK 2025 - Schedule Published
We are excited to announce the schedule for PGDay UK 2025 has been published. We've got an exciting line up for talks over a range of topics. There will be something for everyone attending.
Take a look at what we have going on: https://pgday.uk/events/pgdayuk2025/schedule/
We'd like to extend our gratitude to the whole CFP team, who did an amazing job selecting the talks to make up the schedule.
Wim Bertels: PGConf.be 2025
The shared presentations are online, as are a couple of recordings and turtle-loading have-a-cup-of-tea locally stored photos.
Andrew Farries: pgroll 0.14 - New commands and more control over version schemas
warda bibi: Disaster Recovery Guide with pgbackrest
Recently, we worked with a client who was manually backing up their 800GB PostgreSQL database using pg_dump, which was growing rapidly and had backups stored on the same server as the database itself. This setup had several critical issues:
Andrei Lepikhov: On Postgres Plan Cache Mode Management
Having attended PGConf.DE'2025 and discussed the practice of using Postgres on large databases there, I was surprised to regularly hear the opinion that query planning time is a significant issue. As a developer, it was surprising to learn that this factor can, for example, slow down the decision to move to a partitioned schema, which seems like a logical step once the number of records in a table exceeds 100 million. Well, let's figure it out.
Andrew Atkinson: Avoid UUID Version 4 Primary Keys
Over the last decade, when working on databases where UUID Version 41 was picked as the primary key data type, these databases usually have bad performance and excessive IO.
UUID is a native data type that can be stored as binary data, with various versions outlined in the RFC. Version 4 is mostly random bits, obfuscating information like when the value was created, or where it was generated.
Ilya Kosmodemiansky: Operating PostgreSQL as a Data Source for Analytics Pipelines – Recap from the Stuttgart Meetup
PostgreSQL user groups are a fantastic way to build new connections and engage with the local community. Last week, I had the pleasure of speaking at the Stuttgart meetup, where I gave a talk on “Operating PostgreSQL as a Data Source for Analytics Pipelines.”
Below are my slides and a brief overview of the talk. If you missed the meetup but would be interested in an online repeat, let me know in the comments below!
Esther Minano: Behind the scenes: Speeding up pgstream snapshots for PostgreSQL
Umair Shahid: From 99.9% to 99.99%: Building PostgreSQL Resilience into Your Product Architecture
Most teams building production applications understand that “uptime” matters. I am writing this blog to demonstrate how much difference an extra 0.09% makes.
At 99.9% availability, your system can be down for over 43 minutes every month. At 99.99%, that window drops to just over 4 minutes. If your product is critical to business operations, customer workflows, or revenue generation, those 39 extra minutes of downtime each month can be the difference between trust and churn.
Abhishek Chanda: Running Postgres on Cloudflare Containers
Disclaimer: I work for Cloudflare. The views and opinions expressed in this post are my own and do not necessarily reflect the official policy or position of Cloudflare.
Mankirat Singh: June, BuildFarm and ABIs
Dmitry Dolgov: An example for metrics assisted modeling of database performance
Jan Wieremjewicz: The PG_TDE Extension Is Now Ready for Production
Andreas 'ads' Scherbaum: Samed YILDIRIM
Ian Barwick: PgPedia Week, 2025-06-29
Housekeeping announcements:
this website's PostgreSQL installation is now on version 17 ( insert champagne emoji here ) the search function now works properly with non-ASCII characters ( there was an embarrassing oversight which went unnoticed until someone kindly pointed it out ) PostgreSQL 18 changes this weekThis week there have been a couple of renamings:
Tomas Vondra: How often is the query plan optimal?
The basic promise of a query optimizer is that it picks the “optimal” query plan. But there’s a catch - the plan selection relies on cost estimates, calculated from selectivity estimates and cost of basic resources (I/O, CPU, …). So the question is, how often do we actually pick the “fastest” plan? And the truth is we actually make mistakes quite often.