Remove injector statements from telemetry; give the healthy case real traffic
Browse files- README.md +18 -4
- benchmark.jsonl +6 -6
README.md
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@@ -53,10 +53,24 @@ Measured, not asserted. `python -m evals.baselines` reproduces this table.
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| `slow_and_big` — slowest statement over 10ms **and** a large table → missing index | 2/6 |
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| deterministic detectors (reference implementation) | 6/6 |
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`slow_and_big`
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healthy database.
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## Labels
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| `slow_and_big` — slowest statement over 10ms **and** a large table → missing index | 2/6 |
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| deterministic detectors (reference implementation) | 6/6 |
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`slow_and_big` is right twice: it names the one genuine index problem, and it
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stays quiet on the healthy database. On the other four it returns **nothing at
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all** — once the rig's own statements are excluded (see below), none of those
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faults presents as a slow query. Stale statistics, bloat, a lock holder and an
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N+1 loop are all invisible to any heuristic that ranks by duration.
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## Telemetry contains application traffic only
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Each scenario clears `pg_stat_statements` *after* the fault is created and
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*before* the workload runs, so the injector's own work never reaches the
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snapshot. Without that, `plan_regression` ships with a 9.6-second
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`INSERT INTO orders … generate_series(1, 300000)` and an
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`ALTER TABLE orders SET (autovacuum_enabled = false)` sitting in the statements,
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which name the root cause outright and make the scenario trivial.
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For the same reason the healthy record is captured *after* running the same
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background traffic as every fault case — an empty `statements` list would make
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`len(statements) == 0` a free correct answer.
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## Labels
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benchmark.jsonl
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{"id": "healthy_baseline", "title": "Healthy database", "category": "none", "expected_detector": null, "expected_root_cause": "Nothing is wrong. The correct answer is no finding.", "fix_target": null, "naive_answer": "find something anyway", "naive_answer_correct": false, "telemetry": {"statements": [], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan":
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{"id": "missing_index", "title": "Missing index on a hot foreign key", "expected_detector": "missing_index", "expected_root_cause": "order_items.product_id has no index; the product-lookup query falls back to a sequential scan over the whole table.", "scenario_description": "Drops idx_order_items_product_id and drives product-lookup traffic. The join seq-scans 2.5M rows on every call.", "telemetry": {"statements": [{"queryid": -160921144486592849, "query": "SELECT o.id, o.created_at, oi.quantity\n FROM order_items oi\n JOIN orders o ON o.id = oi.order_id\n WHERE oi.product_id = $1\n ORDER BY o.created_at DESC\n LIMIT $2", "calls": 150, "total_exec_time":
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{"id": "plan_regression", "title": "Plan regression from stale statistics", "expected_detector": "stale_stats", "expected_root_cause": "Statistics on orders are stale after a bulk load. The planner's row estimate for status = 'processing' is off by orders of magnitude, so it picks the wrong plan. Fix is ANALYZE orders, not a new index.", "scenario_description": "Inserts 300k orders with a brand-new status value and blocks autovacuum, so pg_statistic never learns the value exists.", "telemetry": {"statements": [{"queryid":
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{"id": "bloat", "title": "Table bloat \u2014 autovacuum disabled", "expected_detector": "bloat", "expected_root_cause": "autovacuum is disabled on events, so dead tuples from UPDATE churn are never reclaimed. Fix is re-enabling autovacuum and vacuuming.", "scenario_description": "Disables autovacuum on events and runs repeated mass UPDATEs, leaving several hundred thousand dead tuples that never get reclaimed.", "telemetry": {"statements": [{"queryid":
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{"id": "lock_contention", "title": "Lock contention \u2014 idle in transaction", "expected_detector": "lock_contention", "expected_root_cause": "A session is idle-in-transaction holding row locks on orders. Blocked writers are waiting on it. Fix targets the holder, not the waiters.", "scenario_description": "Leaves a session idle-in-transaction holding row locks on 1000 orders rows, plus three writers that block behind it.", "telemetry": {"statements": [{"queryid":
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{"id": "n_plus_1", "title": "ORM N+1 query pattern", "expected_detector": "n_plus_1", "expected_root_cause": "Application-side N+1. order_items is queried once per order row instead of batched. High call count, low mean time, trivial rows per call. Fix is in the application, not the database.", "scenario_description": "Runs 20 pages x 50 rows of list-then-per-row-lookup traffic. No schema change: 1000 fast queries where 20 would do.", "telemetry": {"statements": [{"queryid": 3395054879552150299, "query": "SELECT id, product_id, quantity FROM order_items WHERE order_id = $1", "calls": 1000, "total_exec_time":
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{"id": "healthy_baseline", "title": "Healthy database", "category": "none", "expected_detector": null, "expected_root_cause": "Nothing is wrong. The correct answer is no finding.", "fix_target": null, "naive_answer": "find something anyway", "naive_answer_correct": false, "telemetry": {"statements": [{"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 30, "total_exec_time": 20.982371999999998, "mean_exec_time": 0.6994123999999999, "rows": 151, "shared_blks_read": 156, "shared_blks_hit": 85}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 30, "total_exec_time": 16.109731, "mean_exec_time": 0.5369910333333333, "rows": 255, "shared_blks_read": 302, "shared_blks_hit": 44}, {"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval $2\n ORDER BY created_at DESC\n LIMIT $3", "calls": 30, "total_exec_time": 3.891733999999999, "mean_exec_time": 0.12972446666666665, "rows": 1500, "shared_blks_read": 0, "shared_blks_hit": 1554}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3165, "seq_tup_read": 2642500001, "idx_scan": 2107164, "last_analyze": "2026-08-08 10:39:05.560595+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 263626752, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 124, "seq_tup_read": 127272297, "idx_scan": 950, "last_analyze": "2026-08-08 10:39:08.789028+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 218873856, "autovacuum_enabled": true}, {"relname": "orders", "n_live_tup": 1000000, "reltuples": 1000000, "live_tuples": 1000000, "n_dead_tup": 1000, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2154545, "last_analyze": "2026-08-08 10:39:05.979839+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:05.591915+00:00", "last_autovacuum": null, "total_bytes": 146169856, "autovacuum_enabled": true}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2100000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.025798"}], "blocking": [], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}}
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{"id": "missing_index", "title": "Missing index on a hot foreign key", "expected_detector": "missing_index", "expected_root_cause": "order_items.product_id has no index; the product-lookup query falls back to a sequential scan over the whole table.", "scenario_description": "Drops idx_order_items_product_id and drives product-lookup traffic. The join seq-scans 2.5M rows on every call.", "telemetry": {"statements": [{"queryid": -160921144486592849, "query": "SELECT o.id, o.created_at, oi.quantity\n FROM order_items oi\n JOIN orders o ON o.id = oi.order_id\n WHERE oi.product_id = $1\n ORDER BY o.created_at DESC\n LIMIT $2", "calls": 150, "total_exec_time": 11084.462094999999, "mean_exec_time": 73.89641396666667, "rows": 3000, "shared_blks_read": 1662670, "shared_blks_hit": 1127080}, {"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 40, "total_exec_time": 15.624891, "mean_exec_time": 0.3906222750000001, "rows": 182, "shared_blks_read": 106, "shared_blks_hit": 197}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 40, "total_exec_time": 11.880294, "mean_exec_time": 0.29700735, "rows": 320, "shared_blks_read": 359, "shared_blks_hit": 83}, {"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval $2\n ORDER BY created_at DESC\n LIMIT $3", "calls": 40, "total_exec_time": 3.2147000000000006, "mean_exec_time": 0.08036750000000004, "rows": 2000, "shared_blks_read": 0, "shared_blks_hit": 2096}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3608, "seq_tup_read": 3011320881, "idx_scan": 2107186, "last_analyze": "2026-08-08 10:39:05.560595+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 245825536, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 124, "seq_tup_read": 127272297, "idx_scan": 980, "last_analyze": "2026-08-08 10:39:08.789028+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 218873856, "autovacuum_enabled": true}, {"relname": "orders", "n_live_tup": 1000000, "reltuples": 1000000, "live_tuples": 1000000, "n_dead_tup": 1000, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2161888, "last_analyze": "2026-08-08 10:39:05.979839+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:05.591915+00:00", "last_autovacuum": null, "total_bytes": 146169856, "autovacuum_enabled": true}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2100000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.004672"}], "blocking": [], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}, "category": "indexing", "fix_target": "database", "naive_answer": "add an index", "naive_answer_correct": true}
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{"id": "plan_regression", "title": "Plan regression from stale statistics", "expected_detector": "stale_stats", "expected_root_cause": "Statistics on orders are stale after a bulk load. The planner's row estimate for status = 'processing' is off by orders of magnitude, so it picks the wrong plan. Fix is ANALYZE orders, not a new index.", "scenario_description": "Inserts 300k orders with a brand-new status value and blocks autovacuum, so pg_statistic never learns the value exists.", "telemetry": {"statements": [{"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval $2\n ORDER BY created_at DESC\n LIMIT $3", "calls": 100, "total_exec_time": 7.046200999999999, "mean_exec_time": 0.07046201000000002, "rows": 5000, "shared_blks_read": 0, "shared_blks_hit": 4478}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20", "calls": 40, "total_exec_time": 2.2896690000000004, "mean_exec_time": 0.05724172500000001, "rows": 294, "shared_blks_read": 323, "shared_blks_hit": 92}, {"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 40, "total_exec_time": 1.655956, "mean_exec_time": 0.041398899999999995, "rows": 269, "shared_blks_read": 16, "shared_blks_hit": 371}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3617, "seq_tup_read": 3020000001, "idx_scan": 2107186, "last_analyze": "2026-08-08 10:39:21.018301+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 263626752, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 124, "seq_tup_read": 127272297, "idx_scan": 1020, "last_analyze": "2026-08-08 10:39:08.789028+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 218873856, "autovacuum_enabled": true}, {"relname": "orders", "n_live_tup": 1300000, "reltuples": 1000000, "live_tuples": 1300000, "n_dead_tup": 1000, "n_mod_since_analyze": 300000, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2162107, "last_analyze": "2026-08-08 10:39:05.979839+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:05.591915+00:00", "last_autovacuum": null, "total_bytes": 171507712, "autovacuum_enabled": false}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2400000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.003779"}], "blocking": [], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}, "category": "statistics", "fix_target": "database", "naive_answer": "add an index on orders.status", "naive_answer_correct": false}
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{"id": "bloat", "title": "Table bloat \u2014 autovacuum disabled", "expected_detector": "bloat", "expected_root_cause": "autovacuum is disabled on events, so dead tuples from UPDATE churn are never reclaimed. Fix is re-enabling autovacuum and vacuuming.", "scenario_description": "Disables autovacuum on events and runs repeated mass UPDATEs, leaving several hundred thousand dead tuples that never get reclaimed.", "telemetry": {"statements": [{"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval $2\n ORDER BY created_at DESC\n LIMIT $3", "calls": 30, "total_exec_time": 46.683979999999984, "mean_exec_time": 1.5561326666666664, "rows": 1500, "shared_blks_read": 203, "shared_blks_hit": 1363}, {"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 30, "total_exec_time": 38.372409999999995, "mean_exec_time": 1.2790803333333336, "rows": 142, "shared_blks_read": 179, "shared_blks_hit": 53}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 30, "total_exec_time": 3.0573830000000006, "mean_exec_time": 0.10191276666666664, "rows": 220, "shared_blks_read": 199, "shared_blks_hit": 227}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3617, "seq_tup_read": 3020000001, "idx_scan": 2407186, "last_analyze": "2026-08-08 10:39:21.018301+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 263626752, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 857097, "n_mod_since_analyze": 857140, "seq_scan": 128, "seq_tup_read": 133272297, "idx_scan": 1060, "last_analyze": "2026-08-08 10:39:08.789028+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 389873664, "autovacuum_enabled": false}, {"relname": "orders", "n_live_tup": 1000000, "reltuples": 1000000, "live_tuples": 1000000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2462248, "last_analyze": "2026-08-08 10:39:32.129797+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:31.970793+00:00", "last_autovacuum": null, "total_bytes": 146087936, "autovacuum_enabled": true}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2400000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.007394"}], "blocking": [], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}, "category": "vacuum", "fix_target": "database", "naive_answer": "the table is just large", "naive_answer_correct": false}
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| 5 |
+
{"id": "lock_contention", "title": "Lock contention \u2014 idle in transaction", "expected_detector": "lock_contention", "expected_root_cause": "A session is idle-in-transaction holding row locks on orders. Blocked writers are waiting on it. Fix targets the holder, not the waiters.", "scenario_description": "Leaves a session idle-in-transaction holding row locks on 1000 orders rows, plus three writers that block behind it.", "telemetry": {"statements": [{"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 25", "calls": 30, "total_exec_time": 8.986045000000003, "mean_exec_time": 0.29953483333333336, "rows": 167, "shared_blks_read": 184, "shared_blks_hit": 73}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT $2", "calls": 30, "total_exec_time": 2.9876260000000006, "mean_exec_time": 0.09958753333333334, "rows": 226, "shared_blks_read": 271, "shared_blks_hit": 45}, {"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval '90 days'\n ORDER BY created_at DESC\n LIMIT 50", "calls": 30, "total_exec_time": 2.8328330000000004, "mean_exec_time": 0.09442776666666666, "rows": 1500, "shared_blks_read": 0, "shared_blks_hit": 1563}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3617, "seq_tup_read": 3020000001, "idx_scan": 2407186, "last_analyze": "2026-08-08 10:39:21.018301+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 263626752, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 133, "seq_tup_read": 137984801, "idx_scan": 1090, "last_analyze": "2026-08-08 10:40:12.971612+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 218873856, "autovacuum_enabled": true}, {"relname": "orders", "n_live_tup": 1000000, "reltuples": 1000000, "live_tuples": 1000000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2462309, "last_analyze": "2026-08-08 10:39:32.129797+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:31.970793+00:00", "last_autovacuum": null, "total_bytes": 146169856, "autovacuum_enabled": true}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2400000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.004325"}, {"pid": 15951, "application_name": "dbra_blocker", "state": "idle in transaction", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "UPDATE orders SET updated_at = now() WHERE id BETWEEN 1 AND 1000;", "xact_age": "0:00:02.906086", "state_age": "0:00:02.873810"}, {"pid": 15958, "application_name": "dbra_blocked", "state": "active", "wait_event_type": "Lock", "wait_event": "transactionid", "query": "SET application_name = 'dbra_blocked'; SELECT pg_sleep(2); UPDATE orders SET updated_at = now() WHERE id BETWEEN 1 AND 100;", "xact_age": "0:00:02.543973", "state_age": "0:00:02.543972"}, {"pid": 15965, "application_name": "dbra_blocked", "state": "active", "wait_event_type": "Lock", "wait_event": "transactionid", "query": "SET application_name = 'dbra_blocked'; SELECT pg_sleep(2); UPDATE orders SET updated_at = now() WHERE id BETWEEN 500 AND 600;", "xact_age": "0:00:02.139422", "state_age": "0:00:02.139421"}, {"pid": 15972, "application_name": "dbra_blocked", "state": "active", "wait_event_type": "Timeout", "wait_event": "PgSleep", "query": "SET application_name = 'dbra_blocked'; SELECT pg_sleep(2); UPDATE orders SET total_cents = total_cents WHERE id = 42;", "xact_age": "0:00:01.745437", "state_age": "0:00:01.745435"}], "blocking": [{"waiting_pid": 15958, "waiting_query": "SET application_name = 'dbra_blocked'; SELECT pg_sleep(2); UPDATE orders SET updated_at = now() WHERE id BETWEEN 1 AND 100;", "blocker_pids": [15951]}, {"waiting_pid": 15965, "waiting_query": "SET application_name = 'dbra_blocked'; SELECT pg_sleep(2); UPDATE orders SET updated_at = now() WHERE id BETWEEN 500 AND 600;", "blocker_pids": [15951]}], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}, "category": "locking", "fix_target": "session", "naive_answer": "kill the slow queries", "naive_answer_correct": false}
|
| 6 |
+
{"id": "n_plus_1", "title": "ORM N+1 query pattern", "expected_detector": "n_plus_1", "expected_root_cause": "Application-side N+1. order_items is queried once per order row instead of batched. High call count, low mean time, trivial rows per call. Fix is in the application, not the database.", "scenario_description": "Runs 20 pages x 50 rows of list-then-per-row-lookup traffic. No schema change: 1000 fast queries where 20 would do.", "telemetry": {"statements": [{"queryid": 3395054879552150299, "query": "SELECT id, product_id, quantity FROM order_items WHERE order_id = $1", "calls": 1000, "total_exec_time": 59.843165000000084, "mean_exec_time": 0.059843165000000156, "rows": 2640, "shared_blks_read": 182, "shared_blks_hit": 5458}, {"queryid": 455725342067307130, "query": "SELECT id, status, total_cents, created_at\n FROM orders\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 25", "calls": 30, "total_exec_time": 5.872744, "mean_exec_time": 0.19575813333333333, "rows": 143, "shared_blks_read": 155, "shared_blks_hit": 78}, {"queryid": 6567515492305370512, "query": "SELECT id, user_id, total_cents, created_at\n FROM orders\n WHERE status = $1 AND created_at > now() - interval '90 days'\n ORDER BY created_at DESC\n LIMIT 50", "calls": 30, "total_exec_time": 2.3699559999999993, "mean_exec_time": 0.07899853333333334, "rows": 1500, "shared_blks_read": 0, "shared_blks_hit": 1578}, {"queryid": 7553808779370851911, "query": "SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20", "calls": 30, "total_exec_time": 2.1654740000000006, "mean_exec_time": 0.07218246666666665, "rows": 253, "shared_blks_read": 277, "shared_blks_hit": 66}, {"queryid": -5615481360785558192, "query": "SELECT id FROM orders\n WHERE status = $2\n ORDER BY created_at DESC\n LIMIT $1", "calls": 20, "total_exec_time": 1.368301, "mean_exec_time": 0.06841504999999999, "rows": 1000, "shared_blks_read": 0, "shared_blks_hit": 1000}], "tables": [{"relname": "order_items", "n_live_tup": 2500000, "reltuples": 2500000, "live_tuples": 2500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 3617, "seq_tup_read": 3020000001, "idx_scan": 2408186, "last_analyze": "2026-08-08 10:39:21.018301+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 263626752, "autovacuum_enabled": true}, {"relname": "events", "n_live_tup": 1500000, "reltuples": 1500000, "live_tuples": 1500000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 133, "seq_tup_read": 137984801, "idx_scan": 1123, "last_analyze": "2026-08-08 10:40:12.971612+00:00", "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 218873856, "autovacuum_enabled": true}, {"relname": "orders", "n_live_tup": 1000000, "reltuples": 1000000, "live_tuples": 1000000, "n_dead_tup": 1000, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 2462403, "last_analyze": "2026-08-08 10:39:32.129797+00:00", "last_autoanalyze": null, "last_vacuum": "2026-08-08 10:39:31.970793+00:00", "last_autovacuum": null, "total_bytes": 146169856, "autovacuum_enabled": true}, {"relname": "categories", "n_live_tup": 0, "reltuples": 120, "live_tuples": 120, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 120, "idx_scan": 0, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 32768, "autovacuum_enabled": true}, {"relname": "products", "n_live_tup": 0, "reltuples": 50000, "live_tuples": 50000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 0, "seq_tup_read": 0, "idx_scan": 1, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 5750784, "autovacuum_enabled": true}, {"relname": "users", "n_live_tup": 0, "reltuples": 200000, "live_tuples": 200000, "n_dead_tup": 0, "n_mod_since_analyze": 0, "seq_scan": 1, "seq_tup_read": 200000, "idx_scan": 2400000, "last_analyze": null, "last_autoanalyze": null, "last_vacuum": null, "last_autovacuum": null, "total_bytes": 31318016, "autovacuum_enabled": true}], "activity": [{"pid": 15512, "application_name": "dbra_cli", "state": "idle", "wait_event_type": "Client", "wait_event": "ClientRead", "query": "\n SELECT event_type, created_at\n FROM events\n WHERE user_id = $1\n ORDER BY created_at DESC\n LIMIT 20\n", "xact_age": null, "state_age": "0:00:00.006794"}], "blocking": [], "settings": {"autovacuum": {"name": "autovacuum", "setting": "on", "unit": null}, "autovacuum_naptime": {"name": "autovacuum_naptime", "setting": "10", "unit": "s"}, "effective_cache_size": {"name": "effective_cache_size", "setting": "524288", "unit": "8kB"}, "max_connections": {"name": "max_connections", "setting": "100", "unit": null}, "random_page_cost": {"name": "random_page_cost", "setting": "4", "unit": null}, "shared_buffers": {"name": "shared_buffers", "setting": "32768", "unit": "8kB"}, "work_mem": {"name": "work_mem", "setting": "4096", "unit": "kB"}}}, "category": "application", "fix_target": "application", "naive_answer": "nothing is slow, the database is healthy", "naive_answer_correct": false}
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