NVMes write back vs. write through performance
Recently I was running some benchmarks to double-check that the performance of AMD EPYCs servers delivered by Company A, match the performance of those delivered by Company B. I was using our benchmark automation tool (about which I may write a bit more in the…
Important behaviour change between bash version 4.3 and 4.4
Please be aware about important behaviour change between bash version 4.3 and 4.4. You can observe it for example while migrating from Oracle Linux 7 to 8/CentOS 7 to Rocky Linux 8/etc. as version 7 of RHEL compatible system comes with bash 4.2, whereas version…
Change is the only constant…
I have a feeling that the name of my blog has never been so true :). Since today I work for Proton Technologies AG (https://protonmail.com, https://protonvpn.com). Still as a database engineer, but with completely different database engine – MySQL! Even though Oracle database is a…
How Well a Query Optimizer Handles Subqueries?
At the beginning of December, at the UKOUG Tech17 conference in Birmingham (GB), I presented a comparison of the query optimizers of MySQL 8.0.3 and PostgreSQL 10.1. One of the things I talked about is their ability to handle subqueries. I summarized my findings with…