{ "license": "CC BY 4.0", "recipe": { "slug": "database-lock-waits-and-deadlocks", "title": "Find Database Lock Waits and Deadlocks", "testedWith": "Apache DataFusion 45.2.0", "lastReviewed": "2026-07-28" }, "contract": { "tableName": "database_lock_wait_events", "schema": [ { "name": "timestamp_utc", "type": "Timestamp", "description": "When the lock wait was observed." }, { "name": "database_name", "type": "Utf8", "description": "Approved logical database name." }, { "name": "blocked_query_fingerprint", "type": "Utf8", "description": "Normalized label for the blocked application operation." }, { "name": "blocking_query_fingerprint", "type": "Utf8", "description": "Normalized label for the operation holding the lock." }, { "name": "lock_type", "type": "Utf8", "description": "Controlled lock category." }, { "name": "wait_ms", "type": "Float64", "description": "Observed lock wait in milliseconds." }, { "name": "resolved", "type": "Boolean", "description": "Whether the wait ended without remaining blocked." }, { "name": "deadlock_detected", "type": "Boolean", "description": "Whether the database reported a deadlock outcome." }, { "name": "transaction_id", "type": "Utf8", "description": "Application-safe transaction identifier." }, { "name": "environment", "type": "Utf8", "description": "Deployment environment." } ] }, "query": "SELECT\n database_name,\n blocked_query_fingerprint,\n blocking_query_fingerprint,\n COUNT(*) AS lock_wait_incidents,\n COUNT(DISTINCT transaction_id) AS affected_transactions,\n AVG(wait_ms) AS average_wait_ms,\n MAX(wait_ms) AS maximum_wait_ms,\n SUM(CASE WHEN NOT resolved THEN 1 ELSE 0 END) AS unresolved_incidents,\n SUM(CASE WHEN deadlock_detected THEN 1 ELSE 0 END) AS deadlocks\nFROM database_lock_wait_events\nWHERE timestamp_utc >= now() - INTERVAL '7 days'\n AND environment = 'production'\nGROUP BY\n database_name,\n blocked_query_fingerprint,\n blocking_query_fingerprint\nHAVING COUNT(*) >= 3\nORDER BY deadlocks DESC, maximum_wait_ms DESC;", "fixtureKind": "reproducible", "inputRows": [ { "timestamp_utc": "2026-07-28T18:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 1200, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-1", "environment": "production" }, { "timestamp_utc": "2026-07-28T17:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 900, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-2", "environment": "production" }, { "timestamp_utc": "2026-07-28T16:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 1500, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-3", "environment": "production" }, { "timestamp_utc": "2026-07-28T15:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 2400, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-4", "environment": "production" }, { "timestamp_utc": "2026-07-28T14:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 800, "resolved": true, "deadlock_detected": true, "transaction_id": "lock-txn-1-5", "environment": "production" }, { "timestamp_utc": "2026-07-28T13:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 1700, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-6", "environment": "production" }, { "timestamp_utc": "2026-07-28T12:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 3200, "resolved": false, "deadlock_detected": true, "transaction_id": "lock-txn-1-7", "environment": "production" }, { "timestamp_utc": "2026-07-28T11:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 1100, "resolved": false, "deadlock_detected": false, "transaction_id": "lock-txn-1-8", "environment": "production" }, { "timestamp_utc": "2026-07-28T14:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 300, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-1", "environment": "production" }, { "timestamp_utc": "2026-07-28T13:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 450, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-2", "environment": "production" }, { "timestamp_utc": "2026-07-28T12:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 600, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-3", "environment": "production" }, { "timestamp_utc": "2026-07-28T11:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 550, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-4", "environment": "production" }, { "timestamp_utc": "2026-07-28T10:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 700, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-5", "environment": "production" }, { "timestamp_utc": "2026-07-28T09:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 400, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-6", "environment": "production" } ], "illustrativeInputRows": [ { "timestamp_utc": "2026-07-28T18:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 1200, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-1", "environment": "production" }, { "timestamp_utc": "2026-07-28T17:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 900, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-2", "environment": "production" }, { "timestamp_utc": "2026-07-28T16:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 1500, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-3", "environment": "production" }, { "timestamp_utc": "2026-07-28T15:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 2400, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-4", "environment": "production" }, { "timestamp_utc": "2026-07-28T14:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 800, "resolved": true, "deadlock_detected": true, "transaction_id": "lock-txn-1-5", "environment": "production" }, { "timestamp_utc": "2026-07-28T13:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 1700, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-1-6", "environment": "production" }, { "timestamp_utc": "2026-07-28T12:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "row", "wait_ms": 3200, "resolved": false, "deadlock_detected": true, "transaction_id": "lock-txn-1-7", "environment": "production" }, { "timestamp_utc": "2026-07-28T11:00:00.000Z", "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_type": "transaction", "wait_ms": 1100, "resolved": false, "deadlock_detected": false, "transaction_id": "lock-txn-1-8", "environment": "production" }, { "timestamp_utc": "2026-07-28T14:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 300, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-1", "environment": "production" }, { "timestamp_utc": "2026-07-28T13:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 450, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-2", "environment": "production" }, { "timestamp_utc": "2026-07-28T12:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 600, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-3", "environment": "production" }, { "timestamp_utc": "2026-07-28T11:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 550, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-4", "environment": "production" }, { "timestamp_utc": "2026-07-28T10:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "row", "wait_ms": 700, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-5", "environment": "production" }, { "timestamp_utc": "2026-07-28T09:00:00.000Z", "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_type": "transaction", "wait_ms": 400, "resolved": true, "deadlock_detected": false, "transaction_id": "lock-txn-2-6", "environment": "production" } ], "expectedOutput": { "columns": [ "database_name", "blocked_query_fingerprint", "blocking_query_fingerprint", "lock_wait_incidents", "affected_transactions", "average_wait_ms", "maximum_wait_ms", "unresolved_incidents", "deadlocks" ], "rows": [ { "database_name": "app_production", "blocked_query_fingerprint": "UPDATE orders SET status = ?", "blocking_query_fingerprint": "SELECT order FOR UPDATE", "lock_wait_incidents": 8, "affected_transactions": 8, "average_wait_ms": 1600, "maximum_wait_ms": 3200, "unresolved_incidents": 2, "deadlocks": 2 }, { "database_name": "analytics_production", "blocked_query_fingerprint": "REFRESH customer_summary", "blocking_query_fingerprint": "INSERT customer_event", "lock_wait_incidents": 6, "affected_transactions": 6, "average_wait_ms": 500, "maximum_wait_ms": 700, "unresolved_incidents": 0, "deadlocks": 0 } ] }, "notes": [ "The included synthetic input rows generate the expected output when timestamps are shifted into the documented query window.", "Run this fixture in the public browser SQL playground; the selected query executes locally with DuckDB-Wasm.", "Adapt time windows, thresholds, identities, and business definitions before operational use." ] }