All sections in this case
My contribution
I analyzed the query against user behavior, set the investigation priorities and defined the evidence and release criteria. The tools I used included Copilot, ChatGPT, Redgate SQL Monitor and Dynatrace. Engineering evaluated implementation candidates; product and engineering owners retained test, release and rollback decisions.
What changed
74.9% lower average request response time in UAT
Team release result · 1,000 virtual users · June 28 to July 6, 2026
View test conditionsWhy this problem deserved attention
The team had worked on recurring performance issues for about three years. I directed attention to the highest-impact queries, using CPU time, logical reads and logical writes to help decide what deserved attention first.
Account search was reported to consume 40% of CPU. I examined the query and identified joins and filters that did not serve the way people actually searched. That connected a server hotspot to a specific product question: which query behavior was necessary for the user’s task?
How query impact helped me prioritize
I used Redgate SQL Monitor’s Query Impact ranking to identify queries demanding the most attention. Its logarithmic score combines total CPU time, with a weight of three, and total logical reads and writes.
Impact = log((3 × total CPU time) + total logical reads + total logical writes)
The score located where to investigate. Understanding the search workflow helped me decide which joins and filters served a real user need.
The choices that shaped the product
| Choice examined | Product consequence | My direction |
|---|---|---|
| Which query should we investigate next? | Symptoms can obscure where the most resources are consumed | Use query impact to focus the investigation, then check the user task |
| Use exact matching as the immediate answer | A faster response can make records harder to find | Check how users search and the information they actually have |
| Bundle several improvements into an emergency release | The team has more changes to validate, monitor and reverse together | Push for one bounded emergency change |
| Optimize a read in isolation | Write cost, index maintenance or another workflow can regress | Compare representative read and write behavior with regression checks |
How I led the work
I helped the team choose when a short-term hotfix was needed to provide relief while keeping the longer-term performance goal in view. That meant making the next investigation and emergency scope explicit.
I challenged proposed joins, filters and matching behavior against how people searched. I aligned product, engineering, data, QA, support and release stakeholders around controlled testing, regression checks and an accountable release decision.
Inspect the reasoning
From a signal to a release decision
Reconstructed from the delivered practice. The LLM organized evidence and drafted hypotheses. People controlled testing and production decisions.
Telemetry, query plans, work items and test results.
Connect patterns, identify gaps and draft testable hypotheses.
Choose a bounded candidate, compare behavior and approve the next step.
Inspect the candidate acceptance criteria
| Question | Evidence required | Product consequence |
|---|---|---|
| Can users still find the record? | Representative search and workflow scenarios | Protect the task alongside response time |
| What does the faster read cost? | Read/write comparison, maintenance and downstream checks | Evaluate the whole change |
| Can we explain and reverse it? | Traceable tested version, release scope and rollback readiness | Make a bounded release decision |
What changed under load
Documented team release result · UAT load tests
74.9% lower · June 28 to July 6, 2026
1,000 virtual users. Test configuration recorded as 80 CPUs. Source: July 2026 internal performance update.
The team’s July performance update records the release result. My contribution was to focus the investigation on the highest-impact queries, challenge unnecessary query behavior against how people searched, and keep the next change testable.
Engineering refactored stored procedures. The team added execution-plan review to the pull-request process and UAT load testing before each release, creating a repeatable check against the previous baseline.
Inspect the comparison and test conditions
| Measure | June 28 release baseline | July 6 test | Change |
|---|---|---|---|
| Average request response time | 0.910 seconds | 0.228 seconds | 74.9% lower |
| Request errors | 11,912 | 0 | Zero in the July test |
| Throughput | 146.64 requests/second | 166.90 requests/second | 13.8% higher |
| Total requests processed | 791,961 | 901,418 | 13.8% more |
The update specifies a UAT environment with 1,000 virtual users and an 80-CPU configuration. These figures describe the June 28 and July 6 test runs. They measure the team’s release changes in that environment.
The earlier observation that account search consumed 40% of CPU helped direct the investigation. It is separate from the response-time comparison shown here.
What the team planned next
The next steps in the July update were to continue finding bottlenecks, test reduced CPU capacity, increase simulated users, and extend regression coverage. Those were planned experiments for cost and growth decisions.
What I carry into the next decision
The useful contribution of AI was organizing evidence and proposing a next investigation. The product decision remained whether a candidate preserved the user task and met the conditions for release.
Explore the wider AI practice
Follow the model and release decisions in the Evidence Guide, or inspect its evaluation record.
Explore the full case
Follow the delivery path, constraints and operating decisions in more detail.
Why the problem mattered
Application performance can degrade through the interaction of query shape, data growth, indexing, read patterns, write cost and release scope. Diagnostic evidence was distributed across telemetry, query plans, approved work items, acceptance criteria and UAT results.
Teams needed a faster, more consistent way to connect performance signals to testable product and technical decisions without allowing an LLM to change queries, indexes, infrastructure or production behavior on its own.
The people behind the workflow
- Product and engineering teams
- Application support
- Operational users
- Release stakeholders
Partnered with engineering, data, QA, application support and release stakeholders.
Constraints and exceptions
- A faster read increases write or maintenance cost
- A query-plan change helps one workflow but harms another
- Test data does not represent production distribution
- An LLM recommendation lacks source evidence
- UAT passes while an operational performance guardrail regresses
- Release scope changes after communication is drafted
Product strategy
- Use the LLM to organize approved evidence and propose testable hypotheses, never to execute production changes or approve its own recommendation.
- Evaluate query and indexing changes as read/write trade-offs rather than treating faster reads as a free optimization.
- Require controlled comparisons and regression checks before accepting a performance recommendation.
- Keep production approval, rollback readiness and monitoring thresholds under accountable human ownership.
- Generate release communication only from approved work items, acceptance criteria, UAT evidence and the final release scope.
The product model
- Performance-signal intake
- LLM-assisted evidence synthesis
- Query-plan and indexing hypothesis review
- Read/write trade-off assessment
- Controlled test comparison
- Human approval boundaries
- Post-release monitoring
- Traceable release intelligence
Delivery and adoption
- Aligned product and engineering on the user-visible performance problem
- Defined the signals and controlled evidence required for a decision
- Reviewed AI-generated hypotheses before they entered testing
- Connected acceptance criteria and UAT evidence to release readiness
- Required human approval and version-controlled correction paths
Lessons and next decisions
AI assistance is most useful when it reduces evidence-fragmentation and speeds hypothesis formation while controlled testing and accountable people retain decision authority.
- Improve longitudinal comparison of query and release signals
- Strengthen automated evidence completeness checks
- Evaluate diagnostic usefulness without collecting sensitive production content
From the initial problem to delivery
Performance problem → governed AI-assisted workflow → delivered capability
- Define
Connected user-visible performance problems to the evidence needed for a product and technical decision.
- Validate
Set human approval, controlled comparison, regression and rollback requirements for query and release decisions.
- Deliver
Saw the AI-assisted diagnostic and release-intelligence workflow through initial delivery.
Confidentiality
I’ve generalized the implementation details in this case to protect confidential information.
Schemas, actual query plans and query text, index names, data distributions, production thresholds, infrastructure details and production identifiers are generalized or omitted.