David Budac
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Senior Oracle DBA & Architect · Hamburg

David Budac

I've worked with Oracle databases for over 20 years. I design and run mission-critical Oracle estates, focusing on SQL performance and tuning, high availability and disaster recovery.

Get in touch See projects
01Side projects

Things I've built

Oracle tools, and one agentic tool

github.com/davidbudac

Oracle tools 4

Data Guard Configuration Simulator

Rehearse Data Guard failures without a lab: see whether fast-start failover fires and which observer placement survives.

Data GuardFSFOInteractiveLive simulator

Oracle Execution Plan Visualizer

Paste DBMS_XPLAN output and see the plan as a picture, hotspot and bad estimates called out. Runs entirely in the browser.

TypeScriptBrowser-onlyLive app GitHub

AWR Timeline Comparison

Compares the same hour across recent weeks and z-scores the difference to show which metrics changed when the database feels slow.

PL/SQLAWR19cProject site GitHub

ASH Blocking Sessions

Mines Active Session History for blocking chains and draws who blocked whom, and for how long.

PL/SQLASHEChartsProject site GitHub

Agentic tools 1

Hlas

Press a hotkey, speak, and the text appears at your cursor. Transcription runs on the Mac itself and works offline.

SwiftmacOSMenu bar appLive site GitHub

02Writing

Blog

Notes from the DBA side: administration, SQL performance, APEX

Read all blog posts
3 Apr 2025Latest Administration Where is alert log when diagnostic_dest is not writable? When diagnostic_dest isn't writable, Oracle writes the alert log somewhere else. Where to look when you need it mid-incident. 19 Aug 2024 APEX How to Set Up a Local LLM for APEX 24.1 How to let APEX 24.1 talk to a local LLM (like Llama 3.1) via the OpenAI API. 31 Jul 2024 SQL Performance Intro to Oracle SQL Plan management When the optimizer keeps picking the wrong plan, pin the good one. A walkthrough of creating and forcing a SQL plan baseline. 30 Jun 2024 Administration RMAN-08137 - Who's to blame? RMAN refuses to delete archived logs "needed for standby or upstream capture". How to find which process is holding them.
03Speaking

Talks

Speaking on Oracle and on agentic coding

Oracle2026/27

I'm preparing talks on high availability and AWR-driven performance tuning for database and SRE meetups in 2026/27. If you run one and want a speaker, get in touch.

Get in touch
AITalks · workshops

Talks and workshops on agentic coding, drawn from using AI agents on real codebases.

See the presentations
04About

Twenty years on one platform

I'm a Senior Oracle DBA, architect, and performance consultant. I've spent twenty years on large enterprise databases, starting with 10g on bare metal and working on 19c and Exadata today.

Most of that work has been high availability with RAC and Data Guard, Maximum Availability Architecture, disaster recovery, and performance tuning across AIX, Linux, and Windows. For years I've led technical teams and automated operations for national grid operators and banks.

I live in Hamburg and currently run the Oracle estate of one of Czechia's largest banks.

AreaTechnologies
Databases & platform
Oracle Database 10g–19cExadataOracle Enterprise ManagerDatabase architecture & design
High availability & DR
Oracle RACData GuardMaximum Availability ArchitectureDisaster recovery
Performance & reliability
Performance tuningSRE practicesPatching & upgradesSecurity design
Languages & scripting
SQLPL/SQLShell scriptingPython
Monitoring & tooling
ELK StackGrafanaPrometheus & ZabbixDockerAutomation & monitoring design
Operating systems
AIXLinux (various distros)Windows
05Experience

Where I've worked

Grid operators and banks across five countries

2022–now

Senior Oracle DBA

Československá obchodní banka (ČSOB)

Run the bank's Oracle databases on AIX. Designed and implemented Oracle MAA with RAC and Data Guard, cut planned downtime with automation and Edition-Based Redefinition, and set technical direction for the DBA and development teams.

2006–2022

Oracle Database SME

Unicorn Systems, a.s.

Delivered Oracle architecture, design, development, administration, and performance tuning for clients across Europe, including critical infrastructure. Selected engagements:

  • CZ2021–22
    ČEPS — Exadata implementation

    Technical lead for the Czech grid operator's move to Exadata: deployment, database migration, and the monitoring stack around it.

  • FI2015–20
    eSett oy — Nordic Balance Settlement

    Database architecture and PL/SQL data processing for the system that settles the Nordic electricity market, plus its migration to a new data center.

  • CH2014–20
    SwissGrid AG — Schedule Management

    Designed, implemented, and tuned the databases behind Switzerland's national electricity scheduling.

  • NL2014–16
    TenneT NL — DWH historization

    Led the historization architecture for the Dutch grid operator's data warehouse, and built and tuned the SQL/PL/SQL behind it.

  • SK2012–18
    SEPS, a.s. — Market Management

    Database design, infrastructure administration, and PL/SQL optimization for Slovakia's electricity market system.

  • CZ2006–20
    ČEPS, a.s. — Market Management

    Fourteen years on the Czech electricity market system: database design, major migrations, deployments, and performance tuning.

06Certifications

Credentials

Six credentials, Oracle and Elastic

YearCredentialArea
2022Oracle Certified Professional19c Database Administration
2022Oracle Certified ExpertData Guard 12c
2022Oracle Certified ProfessionalPL/SQL
2022Oracle Certified AssociateSQL
2021Elasticsearch Certified EngineerElastic
2011Oracle Certified AssociateDatabase 10g
07Get in touch

Contact

Got a mission-critical Oracle estate to look after?

Health checks, performance tuning engagements, HA/DR architecture reviews, or ongoing operations. Short or long-term.

Email me [email protected]