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PQUERY-101 · Reproduce the slow inbox

Seed an inbox where one tenant owns most of the closed history

Practice briefTaskFoundational

The existing fixture spreads rows evenly across tenants. It cannot reproduce the large account whose open-work view is slow.

Focused work estimate
1h 15m + prerequisites
Priority in the scenario
Medium
Engineering practice
Synthetic datasets · SQL

Estimated field mix

  • Data engineering50%
  • Quality engineering30%
  • Performance engineering20%

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

No earlier ticket is required. Complete the project setup above.

Acceptance criteria

  • Seed 200,000 rows across 100 tenants with one tenant owning 60% of rows and documented open/closed ratios.
  • Include tied creation times, unassigned work and tenants with no matching rows.
  • Generate deterministic expected inbox IDs for named filter and ordering cases.

Implementation constraints

  • Keep tenant identities fictitious and use a manifest so row counts and skew are explicit.

Verification to include

  • Rebuild from the same seed and compare per-tenant counts and expected inbox results.
  • Run the empty-tenant and timestamp-tie cases and verify a deterministic order.

Deliverables

  • Seed generator, distribution summary and expected-result fixtures

Rollout and recovery

Load only a disposable development database; make the rebuild command reject an unrecognized database target.

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.