Klaus Aschenbrenner
@sqlpassion.at
CEO & Founder of https://SQLpassion.at. SQL Server & PostgreSQL specialist during the day. Astrophotographer during the night. Triathlete in between. Loves low-level system programming in Rust.
Today, I’m excited to announce the lineup for my upcoming SQLpassion online trainings for the next 6 months, featuring several brand-new trainings I’ve been developing over the past few months: www.sqlpassion.at/live-trainin... #sqlpassion #sqlserver #postgres #postgresql
January 1, 2026 at 5:00 PM
Today, I’m excited to announce the lineup for my upcoming SQLpassion online trainings for the next 6 months, featuring several brand-new trainings I’ve been developing over the past few months: www.sqlpassion.at/live-trainin... #sqlpassion #sqlserver #postgres #postgresql
And once again, another sporting year comes to an end:
*) 7,350 km cycling
*) Exactly 1,000 km running
*) 110 km swimming
*) 98 hours of stretching/strength training
Next stops:
*) Duathlon Maissau (April 25)
*) Challenge St. Pölten (May 31)
*) Dolomites Cycling Tour (June 14)
Happy New Year! 🎆
*) 7,350 km cycling
*) Exactly 1,000 km running
*) 110 km swimming
*) 98 hours of stretching/strength training
Next stops:
*) Duathlon Maissau (April 25)
*) Challenge St. Pölten (May 31)
*) Dolomites Cycling Tour (June 14)
Happy New Year! 🎆
December 31, 2025 at 2:25 PM
And once again, another sporting year comes to an end:
*) 7,350 km cycling
*) Exactly 1,000 km running
*) 110 km swimming
*) 98 hours of stretching/strength training
Next stops:
*) Duathlon Maissau (April 25)
*) Challenge St. Pölten (May 31)
*) Dolomites Cycling Tour (June 14)
Happy New Year! 🎆
*) 7,350 km cycling
*) Exactly 1,000 km running
*) 110 km swimming
*) 98 hours of stretching/strength training
Next stops:
*) Duathlon Maissau (April 25)
*) Challenge St. Pölten (May 31)
*) Dolomites Cycling Tour (June 14)
Happy New Year! 🎆
Reposted by Klaus Aschenbrenner
MongoDB Read/Write vs. PostgreSQL Synchronous Replication dev.to/franckpachot...
MongoDB Read/Write vs. PostgreSQL Synchronous Replication
If you are used to SQL databases, MongoDB’s consistency model can be confusing. Typical SQL systems...
dev.to
December 28, 2025 at 10:20 PM
MongoDB Read/Write vs. PostgreSQL Synchronous Replication dev.to/franckpachot...
Reposted by Klaus Aschenbrenner
Had a great first "Database Internals" livestream yesterday.
I'm aiming for more "regular" YouTubing in 2026, much of which will be chopping up interesting segments from the streams.
Speaking of which: new video has DROPPED!
www.youtube.com/watch?v=wdJe...
I'm aiming for more "regular" YouTubing in 2026, much of which will be chopping up interesting segments from the streams.
Speaking of which: new video has DROPPED!
www.youtube.com/watch?v=wdJe...
OLTP vs OLAP and the row / column storage tradeoff
YouTube video by Benjamin Dicken
www.youtube.com
December 30, 2025 at 4:20 PM
Had a great first "Database Internals" livestream yesterday.
I'm aiming for more "regular" YouTubing in 2026, much of which will be chopping up interesting segments from the streams.
Speaking of which: new video has DROPPED!
www.youtube.com/watch?v=wdJe...
I'm aiming for more "regular" YouTubing in 2026, much of which will be chopping up interesting segments from the streams.
Speaking of which: new video has DROPPED!
www.youtube.com/watch?v=wdJe...
Warum schafft es die Erste Bank/Sparkasse im Jahr 2025 nicht, ein PDF automatisiert einzulesen, um eine Kreditkarte auszustellen? Der Umstieg von der Miles & More Kreditkarte von Card Complete auf die Erste Bank/Sparkasse ist der WTF Moment des Jahrzehnts.... www.reddit.com/r/FinanzenAT...
Funktioniert bei euch MM Kreditkarte Anmeldung George?
www.reddit.com
December 30, 2025 at 1:54 PM
Warum schafft es die Erste Bank/Sparkasse im Jahr 2025 nicht, ein PDF automatisiert einzulesen, um eine Kreditkarte auszustellen? Der Umstieg von der Miles & More Kreditkarte von Card Complete auf die Erste Bank/Sparkasse ist der WTF Moment des Jahrzehnts.... www.reddit.com/r/FinanzenAT...
Testing DaVinci Resolve to get rid of my last dependency to Windows - Adobe Premiere...
December 27, 2025 at 7:44 PM
Testing DaVinci Resolve to get rid of my last dependency to Windows - Adobe Premiere...
2026 will be the year of Linux on the desktop! 💪
December 27, 2025 at 3:45 PM
2026 will be the year of Linux on the desktop! 💪
Reposted by Klaus Aschenbrenner
A new blog post about an @awscloud.bsky.social Amazon Aurora PostgreSQL feature that exists in many commercial databases but not in PostgreSQL: adaptive join methods dev.to/aws-heroes/a...
Adaptive Join in Amazon Aurora PostgreSQL
Slow joins in PostgreSQL often result from a nested loop join chosen by the query planner, which...
dev.to
December 24, 2025 at 9:37 AM
A new blog post about an @awscloud.bsky.social Amazon Aurora PostgreSQL feature that exists in many commercial databases but not in PostgreSQL: adaptive join methods dev.to/aws-heroes/a...
Reposted by Klaus Aschenbrenner
If you weren't already sick of me: here's a recording of a talk I gave in November at Jane Street on Intel's Skylake Microarchitecture:
youtu.be/BVVNtG5dgks?...
youtu.be/BVVNtG5dgks?...
Microarchitecture: What Happens Beneath
YouTube video by Jane Street
youtu.be
December 23, 2025 at 11:01 PM
If you weren't already sick of me: here's a recording of a talk I gave in November at Jane Street on Intel's Skylake Microarchitecture:
youtu.be/BVVNtG5dgks?...
youtu.be/BVVNtG5dgks?...
Reposted by Klaus Aschenbrenner
Some light reading for the holidays? 😉
I just posted part 4 of my in-depth series on hash tables, where I investigate the on-disk structure of a spilled hash table.
Enjoy!
#sqlserver #internals
sqlserverfast.com/blog/hugo/20...
I just posted part 4 of my in-depth series on hash tables, where I investigate the on-disk structure of a spilled hash table.
Enjoy!
#sqlserver #internals
sqlserverfast.com/blog/hugo/20...
A deep dive into hash tables, part 4 - SQLServerFast
This is the last part of my blog series about the internals of hash tables in SQL Server. In part 1, I introduced a trick to get data returned in the order of the hash table, that I used in part 2 to ...
sqlserverfast.com
December 23, 2025 at 2:53 PM
Some light reading for the holidays? 😉
I just posted part 4 of my in-depth series on hash tables, where I investigate the on-disk structure of a spilled hash table.
Enjoy!
#sqlserver #internals
sqlserverfast.com/blog/hugo/20...
I just posted part 4 of my in-depth series on hash tables, where I investigate the on-disk structure of a spilled hash table.
Enjoy!
#sqlserver #internals
sqlserverfast.com/blog/hugo/20...
Reposted by Klaus Aschenbrenner
New blog post: examining an Amazon Aurora query planner transformation and manual methods, with notes on COUNT versus other aggregations.
dev.to/aws-heroes/u...
dev.to/aws-heroes/u...
Unnesting Scalar Subqueries into Left Outer Joins in SQL
Relational databases treat your query as a declarative description of the desired result and select...
dev.to
December 23, 2025 at 3:49 PM
New blog post: examining an Amazon Aurora query planner transformation and manual methods, with notes on COUNT versus other aggregations.
dev.to/aws-heroes/u...
dev.to/aws-heroes/u...
After a lot of work over the last days/weeks, I have finally reached a "golden" state for my Home Network. Each major network traffic is now isolated into its own VLAN, which are spread across Ubiquiti and Cisco hardware. I have learned a lot about networking - and troubleshooting! ;-) #Networking
December 22, 2025 at 8:20 PM
After a lot of work over the last days/weeks, I have finally reached a "golden" state for my Home Network. Each major network traffic is now isolated into its own VLAN, which are spread across Ubiquiti and Cisco hardware. I have learned a lot about networking - and troubleshooting! ;-) #Networking
[Blog] Hash Indexes in PostgreSQL: www.sqlpassion.at/archive/2025... #PostgreSQL #postgres #sqlpassion #performance #indexing
Hash Indexes in PostgreSQL – SQLpassion
www.sqlpassion.at
December 22, 2025 at 4:58 PM
[Blog] Hash Indexes in PostgreSQL: www.sqlpassion.at/archive/2025... #PostgreSQL #postgres #sqlpassion #performance #indexing
I'm quite happy with my Ceph-based distributed storage across 3 physical Proxmox hosts.
2x Samsung 980 Pro 2 TB NVMe disks per each host with a dedicated 40GbE backend network on a Cisco Nexus Switch :-) #HomeLab #Performance #Storage
2x Samsung 980 Pro 2 TB NVMe disks per each host with a dedicated 40GbE backend network on a Cisco Nexus Switch :-) #HomeLab #Performance #Storage
December 21, 2025 at 9:49 PM
I'm quite happy with my Ceph-based distributed storage across 3 physical Proxmox hosts.
2x Samsung 980 Pro 2 TB NVMe disks per each host with a dedicated 40GbE backend network on a Cisco Nexus Switch :-) #HomeLab #Performance #Storage
2x Samsung 980 Pro 2 TB NVMe disks per each host with a dedicated 40GbE backend network on a Cisco Nexus Switch :-) #HomeLab #Performance #Storage
Reposted by Klaus Aschenbrenner
Festive 500: Learning through Hobbies
Introduction As the year draws to a close, it’s a time for reflection and setting new goals. It’s also a time to over consume calories! For the last few years in our house we (My wife Traci S L and I) have been participating
blog.robsewell.com/blog/festive...
Introduction As the year draws to a close, it’s a time for reflection and setting new goals. It’s also a time to over consume calories! For the last few years in our house we (My wife Traci S L and I) have been participating
blog.robsewell.com/blog/festive...
December 21, 2025 at 4:11 PM
Festive 500: Learning through Hobbies
Introduction As the year draws to a close, it’s a time for reflection and setting new goals. It’s also a time to over consume calories! For the last few years in our house we (My wife Traci S L and I) have been participating
blog.robsewell.com/blog/festive...
Introduction As the year draws to a close, it’s a time for reflection and setting new goals. It’s also a time to over consume calories! For the last few years in our house we (My wife Traci S L and I) have been participating
blog.robsewell.com/blog/festive...
Reposted by Klaus Aschenbrenner
Log structures are all over the place in databases, but did you know they are used in file systems too?
This week I re-read the iconic LFS paper by Rosenblum / Ousterhout.
The differences between I/O demands on a database vs a general-purpose FS are neat to study.
This week I re-read the iconic LFS paper by Rosenblum / Ousterhout.
The differences between I/O demands on a database vs a general-purpose FS are neat to study.
December 19, 2025 at 9:38 PM
Log structures are all over the place in databases, but did you know they are used in file systems too?
This week I re-read the iconic LFS paper by Rosenblum / Ousterhout.
The differences between I/O demands on a database vs a general-purpose FS are neat to study.
This week I re-read the iconic LFS paper by Rosenblum / Ousterhout.
The differences between I/O demands on a database vs a general-purpose FS are neat to study.
My DDR5 SODIMM investment from 5 days ago has already a better performance than my investment portfolio: +25%!
December 19, 2025 at 9:27 PM
My DDR5 SODIMM investment from 5 days ago has already a better performance than my investment portfolio: +25%!
2x 64GB DDR5 RAM costs currently between EUR 2000 - 2500! WTF? 🤬
December 19, 2025 at 7:08 PM
2x 64GB DDR5 RAM costs currently between EUR 2000 - 2500! WTF? 🤬
„Transporting“ VLAN tags across switches from different vendors… 🙈
December 18, 2025 at 8:25 PM
„Transporting“ VLAN tags across switches from different vendors… 🙈
Getting a 10GbE connection across different VLANs doesn't really work, because each packet must be routed through the router, which costs time - and throughput. The solution is simple: a Multi-Homed host, where the physical NIC has an IP address in each VLAN :-) #HomeNetworking #10G
December 18, 2025 at 7:11 PM
Getting a 10GbE connection across different VLANs doesn't really work, because each packet must be routed through the router, which costs time - and throughput. The solution is simple: a Multi-Homed host, where the physical NIC has an IP address in each VLAN :-) #HomeNetworking #10G
I have created my first VLAN on a Cisco Nexus switch!
December 17, 2025 at 8:13 PM
I have created my first VLAN on a Cisco Nexus switch!
I've just deployed my 1st virtual machine in the @exoscale.com cloud. The deployment was done within *seconds* instead of waiting minutes like with other cloud providers...
December 17, 2025 at 7:01 PM
I've just deployed my 1st virtual machine in the @exoscale.com cloud. The deployment was done within *seconds* instead of waiting minutes like with other cloud providers...
Reposted by Klaus Aschenbrenner
Mein Interview über X und seinen Umgang mit Hass-Postings ist im Berliner @tagesspiegel.de heute auch gedruckt erschienen - und nun auch ohne Paywall online:
www.tagesspiegel.de/kultur/ein-m...
www.tagesspiegel.de/kultur/ein-m...
December 17, 2025 at 7:58 AM
Mein Interview über X und seinen Umgang mit Hass-Postings ist im Berliner @tagesspiegel.de heute auch gedruckt erschienen - und nun auch ohne Paywall online:
www.tagesspiegel.de/kultur/ein-m...
www.tagesspiegel.de/kultur/ein-m...
