Rehearse the inbox index migration while writes continue
The proposed index works after a clean restore. Nobody has checked what happens when creation is interrupted while the application is updating work orders.
- Focused work estimate
- 3h 30m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Database migrations · Recovery
Estimated field mix
- Database engineering60%
- Site reliability30%
- Performance engineering10%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional maintenance service lists open work orders beside years of closed history. A query that was cheap in a small demo now scans far more rows than it returns. Recreate the schema and synthetic workload locally; no customer database or supplied fixture is assumed.
Setup prerequisites
- Create an isolated local database with tenants, work orders and assignment history.
- Seed 200,000 synthetic work orders with documented skew and a repeatable random seed; record PostgreSQL version, settings and resource limits.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Run the migration with a bounded concurrent write fixture and record locks and write failures.
- Detect an interrupted or invalid index and define an idempotent retry procedure.
- Provide an explicit rollback that does not remove an index belonging to another migration.
Implementation constraints
- Use PostgreSQL-supported online index operations with their transaction restrictions; record commands and ownership checks in the runbook.
Verification to include
- Interrupt index creation in the disposable database, inspect its state and exercise recovery.
- Compare work-order counts and IDs before and after migration, retry and rollback while the write fixture runs.
Deliverables
- Migration, interruption rehearsal and operator recovery notes
Rollout and recovery
Require the local concurrent-write rehearsal before proposing deployment; stop if lock duration or data reconciliation violates the stated budget.
Value of the work
For the engineer: Practice reading execution plans, balancing read and write cost, and validating performance without weakening tenant boundaries.
For the team: Create reproducible query diagnostics and reversible index or query proposals for an operational application.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.