@markcallaghan.bsky.social
From a CPU-bound Insert Benchmark for Postgres on 24-core and 32-core servers
* a few small improvements
* possibly a few small regressions thanks to get_actual_variable_range
* too much variance on write-heavy workloads thanks to vacuum
smalldatum.blogspot.com/2026/01/cpu-...
From an IO-bound Insert Benchmark on 24-core and 32-core servers:
* modern MySQL is mostly faster than 5.6.51
* there are few perf regressions after MySQL 8.0
* Postgres is mostly faster than MySQL but has far more variance on write-heavy benchmark steps
smalldatum.blogspot.com/2026/01/io-b...
From a CPU-bound Insert Benchmark on 24-core and 32-core servers:
* modern MySQL has big improvements for writes and big regressions for reads
* Postgres is mostly faster than MySQL
* Postgres has much more variance than MySQL on write-heavy benchmark steps
smalldatum.blogspot.com/2026/01/cpu-...
There might be performance regressions that arrived in Postgres 16 and 18 for write-heavy tests, and which remain in Postgres 18.1. This will take time to explain, debug and confirm. My posts:
* part 1 - smalldatum.blogspot.com/2025/12/io-b...
* part 2 - smalldatum.blogspot.com/2026/01/debu...
My first result using tproc-c from HammerDB to compare Postgres versions 12 through 18 on a small server:
* no regressions
* many improvements for Postgres 17.7 and 18.1
* Postgres remains boring for people who search for regressions
smalldatum.blogspot.com/2026/01/post...
I document fsync latency on the SSDs I use. It would be great if I could always use an enterprise SSD, but for that I need them in the m.2 2280 form factor.
smalldatum.blogspot.com/2026/01/ssds...
The patent expired on my favorite sort algorithm. I hope to see an open-source implementation of it one day.
smalldatum.blogspot.com/2026/01/comm...
Benchmark results for modern RocksDB on an 8-core and 48-core server:
* RocksDB is boring, there aren't regressions
smalldatum.blogspot.com/2025/12/perf...
For IO-bound sysbench vs Postgres on a 48-core server
* QPS in 18.1 is similar to 12.22 for most read-only tests, and up to 1.25X larger for some range queries
* QPS in 18.1 for writes might have a few large regressions
* for 18.1, io_method=io_uring helps
smalldatum.blogspot.com/2025/12/io-b...
IO-bound sysbench vs MySQL on a 48-core server
* for read-only the regressions are smaller than what I measure for CPU-bound sysbench
* for write-heavy the improvements are similar to what I measure for CPU-bound sysbench
smalldatum.blogspot.com/2025/12/io-b...
There are perf regressions for write-heavy sysbench tests in MySQL 8.4 and 9.x
* the regressions are larger with concurrency
* the regressions are worse with gtid_mode=ON and enforce_gtid_consistency=ON and their default changed from OFF to ON in MySQL 9.5
smalldatum.blogspot.com/2025/12/perf...
MySQL 5.6 to 9.5 vs sysbench on a 2-socket server:
* old bad news - there were many large regressions from 5.6 to 5.7 to 8.0
* new bad news - there are some new regressions after MySQL 8.0
smalldatum.blogspot.com/2025/12/sysb...
MySQL 5.6 to 9.5 vs the insert benchmark on a small server
* good news - there are no large regressions after 8.0
* bad news - there are many large regressions from 5.6 to 5.7 to 8.0
smalldatum.blogspot.com/2025/12/the-...
Postgres 18.1 vs the insert benchmark on a small server.
Still boring in a good way - a few small regressions, a few small improvements
smalldatum.blogspot.com/2025/12/the-...
RocksDB on a small Arm server - performance in 10.8 is similar to 6.29 (or better) except for the overwrite test where new CPU overhead in versions 7.x and 8.x, probably from correctness checks, reduce throughput by 7%.
This is boring, in a good way.
smalldatum.blogspot.com/2025/12/rock...
RocksDB is faster when compiled with clang than with gcc
smalldatum.blogspot.com/2025/12/usin...
Postgres 12 to 18 vs sysbench at low and high concurrency.
tl;dr
* a few small regressions
* many more small improvements
* many large improvements starting in PG 17 for write-heavy tests at high-concurrency
smalldatum.blogspot.com/2025/11/usin...
MySQL vs sysbench:
* many large regressions from 5.6 to 5.7 & 5.7 to 8.0
* some small regressions from 8.0 through 9.5
Modern MySQL
* suffers from new CPU overheads at low concurrency
* benefits from changes to reduce mutex contention at high concurrency
smalldatum.blogspot.com/2025/11/usin...
For widely used C++ source, removing header files that are no longer needed (like <cstdint>) will break builds for older releases of dependent projects.
smalldatum.blogspot.com/2025/11/chal...
Watched it and it was excellent.
I will start using 0x.tools soon
I am watching your 2024 p99 conf video right now. Tools look great. When using xtop is there an option to present an aggregated result across many samples?
27.10.2025 16:19 — 👍 1 🔁 0 💬 1 📌 0It has yet to show up on the "on demand" section of the web site
27.10.2025 16:05 — 👍 1 🔁 0 💬 2 📌 0Q: Is RocksDB a good choice if you just want to do point queries for a read-only and IO-bound workload?
A: It depends
smalldatum.blogspot.com/2025/10/how-...
Is there an exception for those of us still traumatized by that Bucky Dent home run? While I haven't been a Red Sox fan, long ago when I watched baseball I could not stand the Yankees.
Bucky Dent does not get to hit home runs in big games.
This was fun to explain.
I was confused at first when looking at flamegraphs where 20% of the samples were from page fault handling while running db_bench with read-heavy and IO-bound workloads.
lnkd.in/g9ZHmuGT
Is it time for TPC-BLOB? DBMS performance and efficiency for workloads with objects larger than the fixed-page size is becoming much more important.
smalldatum.blogspot.com/2025/10/is-i...
Postgres 18.0 looks great vs sysbench on a 32-core server
* Postgres has a few small regressions and many larger improvements from versions 12 to 18.
* There might be several small regressions (<= 3%) from 17.6 to 18.0
smalldatum.blogspot.com/2025/10/post...
Measuring scaleup for Postgres 18.0 using sysbench on a many-core server.
Results are mostly excellent and Postgres continues to be boring in a good way.
smalldatum.blogspot.com/2025/10/meas...
Measuring scaleup for MariaDB using sysbench on a many-core server.
smalldatum.blogspot.com/2025/10/meas...
Postgres 18.0 looks great vs sysbench on a large server (24 cores)
* Postgres has a few small regressions and many larger improvements from versions 12 to 18.
* There might be many small regressions (<= 2%) from 17.6 to 18.0
smalldatum.blogspot.com/2025/09/post...
