Available for new engagements — 2026

Behind Every Great App Is a Quiet Database

I'm Valja Vassileva — an independent Oracle DBA and APEX developer. I help teams tune slow databases, ship internal applications and sleep through the night.

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Oracle 12c → 23ai
APEX 5 → 24
RAC & Data Guard
OCI

15+: Years with Oracle
120+: APEX apps shipped
24/7: DBA support available
EU: Timezone friendly

What I do

Two disciplines, one stack.

Deep database engineering paired with the application layer that sits on top of it — so nothing gets lost between the two.

Explore services

01 · APEX

Oracle APEX development

End-to-end APEX applications — from data model to UX. Custom auth, integrations and upgrades of legacy apps.

02 · DBA

Oracle DBA & tuning

Performance tuning, upgrades, backup/recovery strategy, RAC and Data Guard. Emergency support included.

03 · Advisory

Architecture reviews

A second pair of eyes on your Oracle stack before things go wrong — data model, security, scaling.

04 · Migrations

Version & cloud migrations

Upgrades to 19c/23ai, moves to OCI or on-prem consolidation, with rollback plans that actually work.

Latest writing

From the blog

All posts

Jun 14, 2026 · 7 min

ORA-01555: Snapshot too old — a practical checklist

The classic 'snapshot too old' error rarely means what beginners think. Here is the checklist I run through before touching UNDO_RETENTION.

Oracle DBAUndoTroubleshooting

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May 2, 2026 · 9 min

APEX authentication schemes I actually use in production

SSO, custom or the built-in APEX accounts? After a decade of Oracle APEX projects, here is what I reach for by default — and when I break the rule.

APEXSecurity

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Mar 20, 2026 · 6 min

The hidden performance costs of APEX interactive reports

Interactive Reports are the fastest way to ship an APEX screen — and the fastest way to hide a full-table scan behind a friendly UI.

APEXPerformance

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Have a slow query, a stuck APEX app or a migration on the horizon?

I take on a limited number of engagements each quarter — from one-off audits to long-term retainers.

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