A short guide to Query Plan Explainer
Turn a noisy failure into a shorter investigation.
Read EXPLAIN output locally and surface scans, estimates, and likely query bottlenecks. Here is the practical way to prepare the input, read the output, and decide what to check next.
01
When to reach for it
Redacts the input, checks for a sequential scan, and extracts an observed actual-time range when present. It is most useful when you are dealing with slow query or sequential scan. Start with the smallest example that still shows the behavior.
- Look for slow query, sequential scan, bad estimate.
- Reduce the example until one observation can change the result.
02
How to prepare the input
Paste a focused example in EXPLAIN or EXPLAIN ANALYZE output. Leave out unrelated noise so the result stays easy to verify.
- Use the accepted format: EXPLAIN or EXPLAIN ANALYZE output.
- Keep the facts that make the behavior reproducible.
- Do not treat missing context as a reason to invent an answer.
Example input
Safe sample
Seq Scan on orders (cost=0.00..431.00 rows=21000 width=64) (actual time=0.02..18.40 rows=21000 loops=1) Filter: (status = 'pending')
Run this first to see the shape of the result. Then change one meaningful fact and confirm that the output changes with it.
03
How to read the result
Reports input-derived scan and timing observations without claiming query execution. Read the finding beside the evidence that produced it. The result narrows the next check; it does not claim to have changed your system.
- Separate the observed fact from the suggested next check.
- Prefer the smallest reversible experiment that can confirm or reject the finding.
- Save the output when it belongs in an incident note, review, or handoff.
04
Know the boundary
The analysis is redacted and bounded by the supplied evidence; it is not a security decision or a replacement for verification.