Borja Castro

⋄ Sole technical owner of a Django-based legal document platform handling

thousands of daily transactions, bridging development and infrastructure. ⋄ Investigated a critical PostgreSQL incident: identified connection saturation

(520+ connections) caused by Pgpool-II misconfiguration, with hundreds of

stalled transactions — coordinating the fix with the infrastructure team. ⋄ Optimised slow queries using pg_stat_statements: rewrote NOT IN

subqueries to NOT EXISTS and inserted indexes with CREATE INDEX CONCURRENTLY with zero downtime. ⋄ Built a centralised observability stack (Loki + Promtail + Grafana) and re

placed TimedRotatingFileHandler with concurrent-log-handler to elim

inate log rotation race conditions in production. ⋄ Refactored legacy Django codebase: decoupled business logic and de

livered new features without disrupting live operations.

⋄ Designed and implemented a backend system for automated invoice

processing with automatic field detection and validation — automating 150+

monthly invoices and eliminating manual accounting workflows. ⋄ Built SAP RFC integrations to extract financial data in real time, streamlining

reporting and improving visibility of critical business data. ⋄ Designed and deployed an internal ticketing application centralising re quest management across 6 departments, replacing scattered email work flows and improving response times. ⋄ Migrated core database from MySQL to PostgreSQL, managing data integrity

and minimising operational risk during transition.