10 incident labs · safe simulated systems
Refresh the judgement behind the credential.
Practice the next observation in Guided refresh or Challenge refresh mode. Make decisions under a simulated clock, then use the evidence and feedback to rehearse the relevant certification competency whenever the skill needs refreshing.
These repeatable incident drills run in the browser and are separate from the assessed real-SQL module labs. Use them whenever you want a quick refresher; they do not change your certification record.
Review the certification competencies →Guided refresh
Rebuild the operating model
Read each explanation as you go and follow the strongest evidence boundary.
Challenge refresh
Test recall under a clock
Commit to the next observation first, then use feedback as your debrief.
The replica that stopped replaying
A four-phase investigation that separates impact, transport, replay, and safe response.
Open case →Case 02The migration at the front of the queue
A compact exercise in finding the root of a blocked-write fan-out.
Open case →Case 03The cheap query that became expensive
A compact exercise in ranking statements by aggregate load.
Open case →Case 04The table vacuum cannot clean
A compact exercise in distinguishing vacuum capacity from a pinned cleanup horizon.
Open case →Case 05The pool that consumed every backend
Find the application and session state consuming connection capacity before moving the limit.
Open case →Case 06The volume with ninety minutes left
Separate relation, WAL, temporary, and log growth before attempting reclamation.
Open case →Case 07The backup that stopped completing
Diagnose archive, storage, permission, and duration evidence without declaring protection from stale output.
Open case →Case 08The restore rehearsal that missed its objective
Treat restore time, dependencies, WAL, and validation as parts of one recovery path.
Open case →Case 09The checkpoint that saturated storage
Correlate checkpoint write pressure with latency before changing durability or memory settings.
Open case →Case 10The safe-looking deploy that changed the plan
Connect deploy timing, parameter shapes, plans, locks, and rollback compatibility.
Open case →