yashMaini/postgres-incident-diagnosis

Postgres Incident Diagnosis Benchmark

Real telemetry from a Postgres 16 database in six states — one healthy, five broken — paired with the ground-truth root cause of each.

The task: given the stats views, say what is wrong. Or say that nothing is.

Why this exists

There is no standard benchmark for database incident diagnosis, so everyone building an AI SRE tool invents their own eval. This is a small, reproducible one with a specific property: on four of the five faults, the obvious answer is wrong.

id	what a naive answer says	actually correct
missing_index	add an index	✅ yes
plan_regression	add an index	❌ run ANALYZE — the schema is fine
bloat	the table is just large	❌ dead tuples, autovacuum is off
lock_contention	kill the slow queries	❌ they're victims; one holder is at fault
n_plus_1	nothing is slow, it's healthy	❌ 1000 calls at 0.04ms each
healthy_baseline	find something anyway	❌ the answer is "no finding"

The healthy baseline is included deliberately: a diagnostic tool that invents problems on a working database is worse than one that misses them.

Baselines

Measured, not asserted. python -m evals.baselines reproduces this table.

approach	score
always_index — always name something; for a database that's usually an index	1/6
slow_and_big — slowest statement over 10ms and a large table → missing index	2/6
deterministic detectors (reference implementation)	6/6

slow_and_big is right twice: it names the one genuine index problem, and it stays quiet on the healthy database. On the other four it returns nothing at all — once the rig's own statements are excluded (see below), none of those faults presents as a slow query. Stale statistics, bloat, a lock holder and an N+1 loop are all invisible to any heuristic that ranks by duration.

Telemetry contains application traffic only

Each scenario clears pg_stat_statements after the fault is created and before the workload runs, so the injector's own work never reaches the snapshot. Without that, plan_regression ships with a 9.6-second INSERT INTO orders … generate_series(1, 300000) and an ALTER TABLE orders SET (autovacuum_enabled = false) sitting in the statements, which name the root cause outright and make the scenario trivial.

For the same reason the healthy record is captured after running the same background traffic as every fault case — an empty statements list would make len(statements) == 0 a free correct answer.

Labels

expected_detector is one of missing_index, stale_stats, bloat, lock_contention, n_plus_1, or null for the healthy case. Six records, one per class, so treat this as a probe rather than a training set.

Fields

field	description
id	scenario identifier
title	human-readable name
expected_root_cause	ground truth, free text
expected_detector	ground-truth label, null when healthy
category	indexing, statistics, vacuum, locking, application, none
fix_target	whether the fix is in the database, a session, or the application
naive_answer	what a pattern-matching tool would say
naive_answer_correct	whether that happens to be right
telemetry.statements	pg_stat_statements rows
telemetry.tables	pg_stat_user_tables + size + autovacuum_enabled
telemetry.activity	pg_stat_activity rows
telemetry.blocking	waiter → blocker edges from pg_blocking_pids()
telemetry.settings	relevant pg_settings values

Usage

from datasets import load_dataset

ds = load_dataset("yashMaini/postgres-incident-diagnosis", split="train")

correct = 0
for r in ds:
    prediction = your_model(r["telemetry"])   # -> a detector name, or None
    correct += prediction == r["expected_detector"]

print(f"{correct}/{len(ds)}")

telemetry holds the raw stats rows. A useful prompt is usually telemetry["statements"] plus telemetry["tables"]; lock_contention is only solvable from telemetry["blocking"], which is the point of including it.

Reproducing

The telemetry is generated, not hand-written — each row is captured from a live Postgres after a scripted fault injection, against a deterministic 5.2M row dataset (setseed(0.42)).

git clone https://github.com/Yashmaini30/pg-reliability-agent
docker compose up -d --build
python -m evals.export_benchmark --out data/

The reference implementation in that repo scores 5/5 detected, 5/5 ranked first, 0 findings on the healthy baseline using deterministic rules and EXPLAIN (GENERIC_PLAN) — no model in the detection path.

Project overview, with the findings the detectors produce for each scenario: https://huggingface.co/spaces/yashMaini/pg-reliability-agent (a static page — the clickable sandbox runs locally from the repo above).

Caveats

• Six records. This is a sharp probe, not a broad benchmark.
• Synthetic e-commerce schema, single Postgres 16 instance.
• Absolute timings reflect the machine that generated it; the ratios are the signal, not the milliseconds.