{"Entry":{"collection":"waitevent","key":"io/LogicalSubxactRead","name":"LogicalSubxactRead","aliases":["LogicalSubxactRead"],"metadata":{"aliases":["LogicalSubxactRead"],"changed_in":[],"changes":[{"from":"13","moved":null,"renamed":null,"reworded":null,"status":"added","to":"14"},{"from":"14","moved":null,"renamed":null,"reworded":null,"status":"removed","to":"15"}],"content_hash":"bf503c6004c06be058278b2d47c2bdc3c9795cfd0f05a88419b6b55419257e0e","dossier":{"actions":{"en":["Confirm the workload phase should touch this file class.","Correlate with pg_stat_io where available and per-device latency.","Fix the access path, burst shape, or affected storage tier before tuning unrelated memory settings."],"zh":["确认当前负载阶段本来就应访问这类文件。","在可用版本上关联 pg_stat_io 与具体设备延迟。","先修复访问路径、突发形状或受影响存储层，再调整无关的内存参数。"]},"diagnostic_sql":[{"id":"sessions","min_version":"13","sql":"SELECT pid, backend_type, usename, datname, application_name,\n       state, now() - query_start AS query_age,\n       now() - xact_start AS xact_age,\n       wait_event_type, wait_event,\n       pg_blocking_pids(pid) AS blocking_pids,\n       left(query, 160) AS query\nFROM pg_stat_activity\nWHERE wait_event_type = 'IO'\n  AND wait_event = 'LogicalSubxactRead'\nORDER BY query_age DESC NULLS LAST;","title":"Sessions waiting on IO/LogicalSubxactRead","title_zh":"正在等待 IO/LogicalSubxactRead 的会话"},{"id":"cohort","min_version":"13","sql":"SELECT wait_event, count(*) AS waiting_sessions,\n       count(*) FILTER (WHERE state = 'active') AS active_waiters,\n       max(now() - query_start) AS oldest_query\nFROM pg_stat_activity\nWHERE wait_event_type = 'IO'\nGROUP BY wait_event\nORDER BY waiting_sessions DESC, wait_event;","title":"Current IO cohort","title_zh":"当前 IO 等待分布"},{"id":"lock_objects","min_version":"13","sql":"SELECT a.pid, l.locktype, l.mode, l.granted, l.fastpath,\n       d.datname, n.nspname, c.relname,\n       l.page, l.tuple, l.virtualxid, l.transactionid,\n       l.classid, l.objid, l.objsubid\nFROM pg_stat_activity AS a\nLEFT JOIN pg_locks AS l ON l.pid = a.pid\nLEFT JOIN pg_database AS d ON d.oid = l.database\nLEFT JOIN pg_class AS c\n  ON c.oid = l.relation\n AND l.database = (\n       SELECT oid FROM pg_database WHERE datname = current_database()\n     )\nLEFT JOIN pg_namespace AS n ON n.oid = c.relnamespace\nWHERE a.wait_event_type = 'IO'\n  AND a.wait_event = 'LogicalSubxactRead'\nORDER BY a.pid, l.granted, l.locktype, l.mode;","title":"Lock and relation context for these sessions","title_zh":"这些会话的锁与关系上下文"}],"emission":{"active_ranges":[],"dormant_ranges":["14"],"evidence":[{"label":"pgsql-hackers confirmation","url":"https://www.postgresql.org/message-id/ff077840-3ab2-04dd-bbe4-4f5dfd2ad481%40oss.nttdata.com"}],"reason":"catalogued but never reported; removed in PG15","status":"dormant"},"gucs":["autovacuum_freeze_max_age","vacuum_freeze_table_age"],"incident_pattern":{"en":"","zh":""},"mechanism":{"en":"The catalog identity is present, but source audit found no live reporter in 14. Known active ranges: none. The definition location below is retained as negative evidence; this exact release cannot emit the event from a core code path. Evidence: [pgsql-hackers confirmation](https://www.postgresql.org/message-id/ff077840-3ab2-04dd-bbe4-4f5dfd2ad481%40oss.nttdata.com).","zh":"目录中仍保留该身份，但源码审计确认在 14 已没有活动报告点。已知曾可触发范围：none。下方定义位置作为负面证据保留；当前精确版本不会从核心代码路径发出此事件。 证据：[pgsql-hackers confirmation](https://www.postgresql.org/message-id/ff077840-3ab2-04dd-bbe4-4f5dfd2ad481%40oss.nttdata.com)。"},"metrics":["waiting_sessions","wait_event_share","oldest_transaction_age","io_read_time","io_write_time"],"normal":{"en":"No live core occurrence is expected on the audited release.","zh":"在已审计的精确版本上，不应出现活动的核心触发。"},"official_descriptions":{"14":"Waiting for a read from a logical subxact file."},"record_kind":"event","source_locations":[{"commit":"6b3806732b7c5df06bdd0ed150e8a07b4ad62315","excerpt":"event_name = \"LogicalSubxactRead\";","grep_pattern":"LogicalSubxactRead","grep_verified":true,"kind":"catalog_definition","line":733,"major":14,"path":"src/backend/utils/activity/wait_event.c","status":"catalog_only","symbol":"LogicalSubxactRead","tag":"REL_14_24","url":"https://github.com/postgres/postgres/blob/REL_14_24/src/backend/utils/activity/wait_event.c#L733","version":"14.24"}],"source_status":"catalog_only","trouble":{"en":"If telemetry shows it, verify the exact patch version, extension origin, and whether the sample is stale or came from a different server.","zh":"若监控仍显示它，应核对精确小版本、扩展来源，并确认样本是否陈旧或来自另一台服务器。"}},"first_version":"14","has_dossier":true,"imported_at":"2026-09-14T21:49:49.90528+08:00","key":"io/logicalsubxactread","last_version":"14","name":"LogicalSubxactRead","position":79,"present_in":["14"],"slug":"logical-subxact-read","source_rev":"english-manuals:f6949f52973fbaf254e1585ee878d2d5e4d0e3f2cd04126123456760cdc6cc1e","summary":"Waiting for a read from a logical subxact file.","summary_zh":"","type":"IO","type_slug":"io","type_variants":["IO"]}},"Definition":{"Collection":"waitevent","Key":"io/LogicalSubxactRead","SourceDatabase":"center","Version":"14","SourceTable":"waitevent","SourceKey":"io/logicalsubxactread","SourceRevision":"english-manuals:f6949f52973fbaf254e1585ee878d2d5e4d0e3f2cd04126123456760cdc6cc1e","Facts":{"description":"Waiting for a read from a logical subxact file.","description_zh":"","doc":{"anchor":"WAIT-EVENT-IO-TABLE","file":"monitoring-stats.html","lang":"en","sha256":"1852c6205d68e465d08dd8f75e3b6bfdd4a475ee8d79886e2dcff6bff8e2d243","slug":"14"},"lang":"en","name":"LogicalSubxactRead","source":"english-manual","type":"IO","zh_from":""},"ManualEvidence":{"doc":{"anchor":"WAIT-EVENT-IO-TABLE","file":"monitoring-stats.html","lang":"en","sha256":"1852c6205d68e465d08dd8f75e3b6bfdd4a475ee8d79886e2dcff6bff8e2d243","slug":"14"}},"MeasuredEvidence":{}},"Text":{"Collection":"waitevent","Key":"io/LogicalSubxactRead","SourceDatabase":"pgweb","Version":"14","Locale":"zh-Hans","Title":"LogicalSubxactRead","Summary":"等待从逻辑子事务文件读取。","BodyHTML":"\u003cp\u003e等待从逻辑子事务文件读取。\u003c/p\u003e","SourceRevision":"2026-08-31@34d13c8","ContentHash":"ccb2dbaa22e4d4073fa2c75266886bd9b66ef2f342dd05fc73fc130c1dc11860","Payload":{"description_zh":"等待从逻辑子事务文件读取。","zh_from":"doc"}},"RequestedLocale":"zh-Hans","Fallback":false,"Versions":["14"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}