Capability evidence
High-stakes examination processing at institutional scale, where a calculation error or an hour of downtime during a live cycle cannot be undone after the fact.
01Context
Examination processing compresses enormous operational load into a few weeks a year. Hundreds of thousands of student records, millions of scanned pages, evaluators working in parallel against deadlines, and results that determine people’s futures. The system cannot be taken down for maintenance, and a wrong total is not a bug report — it is an appeal.
02What was going wrong
03Approach
Systematic fault isolation rather than trial-and-error. Trace the fault through the complete workflow, optimise the joins and indexes where the cost is structural, correct the business logic at the layer where the rule belongs, validate the output with the stakeholders who depend on the number, then deploy without interrupting work already in progress.
Every slow query was read through its plan. Implicit conversions and table scans were the recurring causes — not the ones people assumed.
The environment ran SQL Server 2014. Modern syntax was unavailable, so solutions were engineered against the version actually deployed rather than the one the documentation assumes.
Anomaly detection built into the calculation pipeline, so outliers surface automatically instead of depending on someone noticing.
Fixes went into production during active examination periods without interrupting them. The release plan was as engineered as the fix.
04What was built
05Outcome
99.9% availability sustained through continuous 20-plus-day examination cycles. Execution-plan-driven optimisation of legacy T-SQL produced a 40% reporting performance improvement. Automated result calculation and anomaly detection reduced manual audit time by 50%.
Delivered as an employee contribution to client-owned platforms, presented here as capability evidence. The figures above were achieved by our principal engineer in that role. No client system, schema, stored procedure or business rule is reproduced, offered or transferable from that work.
We will walk through the architecture, the constraints and the parts that went wrong — on a call, without a deck.