{ "caseId" : "chat-mysql-connection-pool", "query" : "MySQL connection pool is exhausted. How should I diagnose it?", "retrievedAt" : "2026-07-28T06:54:51.843450400Z", "searchMode" : "hybrid", "kbScope" : "rag-eval", "lookupResult" : { "found" : true, "evidenceBlocks" : [ { "docId" : "mysql-connection-pool", "chunkIndex" : 2, "evidenceKey" : "mysql-connection-pool#chunk-2", "source" : "mysql-connection-pool", "title" : "Connection Pool", "breadcrumb" : "Database > MySQL > Connection Pool", "retrievalLayer" : "L1", "content" : "### Connection Pool\n\nWhen MySQL connection pool is exhausted, first compare application pool usage with database `max_connections`.\nFor HikariCP, check `active`, `idle`, `pending`, and connection acquisition timeout metrics.\n\nRecommended diagnosis:\n\n1. Verify whether HikariCP active connections stay near maximum while pending threads grow.\n2. Check MySQL `Threads_connected`, `Threads_running`, and `max_connections`.\n3. Inspect slow SQL and long transactions that keep connections checked out.\n4. If the database is healthy, look for application connection leaks or missing transaction boundaries.\n\nUse this runbook as evidence for connection pool, max_connections, and HikariCP incidents.", "score" : 0.032786883413791656, "hitReasons" : [ "semantic_rank:1", "attempt:FILTERED_VECTOR", "l0_domain_overlap", "l0_entity_overlap", "l0_keyword_overlap" ] }, { "docId" : "mysql-connection-pool", "chunkIndex" : 1, "evidenceKey" : "mysql-connection-pool#chunk-1", "source" : "mysql-connection-pool", "title" : "MySQL", "breadcrumb" : "Database > MySQL > Connection Pool", "retrievalLayer" : "L1", "content" : "## MySQL", "score" : 0.032258063554763794, "hitReasons" : [ "semantic_rank:2", "attempt:FILTERED_VECTOR", "l0_domain_overlap" ] } ], "contextPack" : { "packedText" : "[Evidence 1]\nsource: mysql-connection-pool\ntitle: Connection Pool\nbreadcrumb: Database > MySQL > Connection Pool\nlayer: L1\nreasons: semantic_rank:1, attempt:FILTERED_VECTOR, l0_domain_overlap, l0_entity_overlap, l0_keyword_overlap\ncontent:\n### Connection Pool\n\nWhen MySQL connection pool is exhausted, first compare application pool usage with database `max_connections`.\nFor HikariCP, check `active`, `idle`, `pending`, and connection acquisition timeout metrics.\n\nRecommended diagnosis:\n\n1. Verify whether HikariCP active connections stay near maximum while pending threads grow.\n2. Check MySQL `Threads_connected`, `Threads_running`, and `max_connections`.\n3. Inspect slow SQL and long transactions that keep connections checked out.\n4. If the database is healthy, look for application connection leaks or missing transaction boundaries.\n\nUse this runbook as evidence for connection pool, max_connections, and HikariCP incidents.\n\n[Evidence 2]\nsource: mysql-connection-pool\ntitle: MySQL\nbreadcrumb: Database > MySQL > Connection Pool\nlayer: L1\nreasons: semantic_rank:2, attempt:FILTERED_VECTOR, l0_domain_overlap\ncontent:\n## MySQL", "strategy" : "ranked_evidence_char_budget", "charBudget" : 4000, "usedChars" : 1135, "includedSources" : [ "mysql-connection-pool", "mysql-connection-pool" ], "omittedSources" : [ ] }, "retrievalTrace" : { "originalQuery" : "MySQL connection pool is exhausted. How should I diagnose it?", "rewrittenQuery" : "MySQL connection pool is exhausted. How should I diagnose it?", "categoryFilter" : "database", "selectedAttempt" : "FILTERED_VECTOR", "fallbackReason" : null, "evidenceStatus" : "supported", "queryHints" : { "domains" : [ "database" ], "matched_keywords" : [ "MySQL connection pool" ], "entities" : [ "MySQL connection pool" ], "l0_titles" : [ "MySQL Connection Pool Runbook" ], "l0_match_count" : 1 }, "attempts" : [ { "name" : "FILTERED_VECTOR", "query" : "MySQL connection pool is exhausted. How should I diagnose it?", "categoryFilter" : "database", "candidateCount" : 3, "usable" : true, "errorMessage" : null, "durationMs" : 5267, "topScore" : 0.032786883413791656, "topSimilarity" : 0.8114794194698334 } ] }, "rerankTrace" : { "items" : [ { "finalRank" : 1, "source" : "mysql-connection-pool", "baseScore" : 0.8114794194698334, "finalScore" : 0.8114794194698334, "boostReasons" : [ "l0_domain_overlap", "l0_entity_overlap", "l0_keyword_overlap" ] }, { "finalRank" : 2, "source" : "mysql-connection-pool", "baseScore" : 0.49219560623168945, "finalScore" : 0.49219560623168945, "boostReasons" : [ "l0_domain_overlap" ] } ] }, "evidenceCandidateCount" : 3, "evidenceBlockCount" : 2, "relevanceLevel" : "PRECISE", "completenessHint" : "知识库中不存在比上述结果更精准的文档", "retrievedDomainsThisSession" : null, "message" : null } }