Diagnose and Fix Query-Planner Misestimates in a FinTech Warehouse
Overview
What this challenge is about.
For each of the 6 queries, capture EXPLAIN (ANALYZE, BUFFERS) and compare estimated vs actual rows at each node. Identify the misestimate source per query (single-column stats stale, correlated columns missing extended stats, function-call estimates, parallel-plan thresholds). Fix with ANALYZE, CREATE STATISTICS, planner-hint extensions only if absolutely necessary. Validate the fix and ensure no regression on the other 22 reports. Deliver a per-query diagnosis, the applied fixes, the validation report, and an 8-page planner-tuning playbook.
The Brief
What you'll do, and what you'll demonstrate.
Diagnose 6 planner-misestimate-driven slow queries on a 4.2 TB PostgreSQL warehouse, fix them, and write a tuning playbook the team can reuse.
Earning criteria — what you'll demonstrate
- Read EXPLAIN (ANALYZE, BUFFERS) deeply enough to spot misestimates
- Apply CREATE STATISTICS to correlated and dependent columns
- Validate fixes against non-target queries to prevent regression
- Write a tuning playbook that lasts beyond the immediate fix
Program Fit
Where this fits in your program.
Sharpens the same skills your degree expects you to demonstrate.
Skills
Skills you'll demonstrate.
Each one shows up on your verified credential.
Careers
Roles this prepares you for.
Real titles. Real skill bridges. Pick the one closest to your trajectory.
Career mappings coming soon.