Developer Offshore research
When does a PostgreSQL prepared statement choose a generic plan?
· Research report
A reproducible protocol for one prepared query tested against a fixed PostgreSQL version, schema, statistics snapshot, and parameter set. It keeps observations separate from interpretation and states where the finding stops.
Use this report with the Research library and the related daily developer guides to turn evidence into a bounded work brief.
Key Stats
- 1 declared unit of analysis
- 8 recorded signal classes
- 2 mechanism-specific primary references
Key Takeaways
- Retain plan type, planning time, execution time, row estimates, parameters, custom-plan count, and generic-plan count.
- Test whether warming effects or changed statistics may explain the timing difference rather than plan selection.
- Apply results only to the pinned revision, configuration, workload, environment, and observation window.
Research question and scope
Research question: When does a PostgreSQL prepared statement choose a generic plan? The unit of analysis is one prepared query tested against a fixed PostgreSQL version, schema, statistics snapshot, and parameter set. The study does not sample users, organizations, or unrelated configurations.
Before testing, pin code and dependency revisions, configuration, fixture identities, workload, network path, clock, and observation window.
Methodology
Run a baseline, target condition, repeated target, interrupted run, and recovery run with synthetic data. Record plan type, planning time, execution time, row estimates, parameters, custom-plan count, and generic-plan count. Preserve raw output before annotation.
Change one independent condition per comparison. Use the same warm-up, run count, timeout, and collection commands. Log failed and excluded runs with a reason.
Source basis and protocol choices
PostgreSQL PREPARE defines the mechanism under test. PostgreSQL Plan Cache Mode supplies a second standards or implementation reference for fixture and field selection.
The references shape the protocol but do not establish the local result. Measurements must support every claim about this system.
Inference boundaries
The primary inference compares recorded behavior inside the fixed test matrix. Timing alone does not prove causation. Try to disconfirm it by testing whether warming effects or changed statistics may explain the timing difference rather than plan selection.
Do not generalize to other versions, regions, workloads, or implementations. Keep unexpected results as observations until a controlled run separates the explanations.
Limitations
This protocol covers one prepared query tested against a fixed PostgreSQL version, schema, statistics snapshot, and parameter set. It cannot measure unobserved production traffic, every external failure, all implementations, or behavior after an upgrade. Clock precision, warm caches, background load, and instrumentation may affect measurements.
Report missing cases, uncertainty, the raw-data location, excluded runs, and the observation that would overturn the provisional conclusion.
Ownership and review
An offshore developer may prepare fixtures, run the approved protocol, add focused instrumentation, and draft a reversible correction. Internal security, data, platform, and release owners control sensitive access and production action.
A reviewer should reproduce one baseline and one boundary run from the recorded commands before accepting a conclusion.
References
Primary protocol references: PostgreSQL PREPARE and PostgreSQL Plan Cache Mode. Their URLs appear below. Record the exact version or retrieval date used during execution.
Evidence table
| Signal | What to inspect | Owner |
|---|---|---|
| Outcome | Acceptance evidence for the bounded task | Task reviewer |
| Control | Access, test, and approval boundary | Internal owner |
| Handoff | Open risks and next decision | Next owner |
Good distributed work is observable at the handoff: the result, evidence, limitations, and next owner are all explicit.
Frequently asked questions
Does this result apply to the whole platform?
No. It applies only to the declared unit, pinned revisions, configuration, workload, environment, and observation window.
What would change the conclusion?
A controlled run showing that warming effects or changed statistics may explain the timing difference rather than plan selection, or another recorded explanation, accounts for the observation would require a new conclusion.