Independent MySQL, MariaDB & Aurora MySQL consulting
Specialist performance investigations for software teams and agencies. Work directly with Krzysztof Książek on slow queries, recurring locking problems, and unexplained database latency—with clear findings and a prioritised plan for your engineers.
Fixed scope. Scheduled delivery. No ongoing support contract required.
Why does the order-history page become slow for some tenants, and what should the team test first?
Capture execution plans and statement statistics for two large tenants.
Synthetic MySQL scenario; no customer data or measured results.
Read the MySQL sample →Who does the work
DB-Ex is an independent database consultancy led by Krzysztof Książek. I handle the scoping, investigation, written findings, and technical handover personally.
Database reliability engineer on a large Amazon Aurora fleet since April 2025, including major version upgrades and schema and query work with development teams. Before that, MySQL operations and performance reviews as an operational DBA (2012–2015).
Career summary →Explore selected database articles and see how I structure an investigation — from evidence and uncertainty to recommended next steps.
Head of Support at Severalnines (2019–2025) after four years as a senior support engineer: complex customer escalations on MySQL and MariaDB, technical guides and webinars, and a Percona Live Europe talk on MySQL load balancers.
Where a focused investigation helps
A focused investigation helps establish what the evidence supports before choosing the next change.
How the diagnostic works →Clarify the assumptions, risks, and validation steps around a defined performance question.
What the review covers →Bring a specialist into the investigation while your team retains delivery ownership.
Working with agencies →The main offer
A focused investigation of your database problem. Written findings, prioritised next steps, and a technical handover to your team.
One environment and one principal question, with the scope, fee, and schedule agreed before work begins. Fixed fee, agreed after a short scope review.
For agencies and consultancies
When a client's MySQL problem needs a deeper investigation, bring in focused expertise without expanding your permanent team.
You retain the client relationship and implementation work. I provide the database investigation, written findings, and handover to your technical team.
Selected proof and technical writing
A successful backup job does not prove you can recover. This lab restores a backup as a replica and records the evidence for each scenario.
Asynchronous replication or Galera Cluster, compared across one, two and three data centres: failover, split-brain risk and the cost of network latency.
The full structure of a diagnostic report: evidence with its provenance, findings separated from hypotheses, missing evidence, and validation steps.
Describe the system, the problem, and what you need to find out. We can then establish whether a focused engagement is the right next step.