{"Entry":{"collection":"guc","key":"ignore_system_indexes","name":"ignore_system_indexes","aliases":[],"metadata":{"baseline":false,"boot_human":"Not specified","boot_val":null,"category":"Developer Options","category_zh":"","changed_in":[],"changes":[{"documentation_changed":false,"fields":{},"from":"8.1","status":"added","to":"8.2"}],"content_hash":"d87fab6126783e7ae4999b24a5db09a0d9b9a2481f33d4709d85a281cc9154f9","context":"","default_changed_in":[],"default_history":[{"from":"9.0","to":"19","value":"off"}],"editorial":{"advice":{"olap":"Read-only analytics does not make ignore_system_indexes safe: corrupted pages can still poison results or structures. Use only on a disposable salvage copy with explicit acceptance of lost data.","oltp":"Never use ignore_system_indexes as tuning or a steady-state availability setting. Stop writes, preserve immutable copies, exhaust backup/storage repair, document expected data loss, salvage narrowly, rebuild, and validate before any return to service.","small":"Do not enable ignore_system_indexes merely because no replica exists. Preserve the original first and seek a clean backup; this switch can convert visible corruption into silent loss."},"mechanism":["ignore_system_indexes makes a newly started backend read system catalogs without using their indexes, while catalog modifications still update the indexes. It is intended to recover from damaged system indexes.","Because its backend context is fixed at session start, changing the setting inside an existing session is ineffective. Catalog scans can become very slow.","The mode does not repair an index; it only creates a path to inspect data and REINDEX the damaged system index. Leaving it enabled hides symptoms and imposes broad catalog overhead. Its backend context fixes the value during connection startup; an existing session cannot change it."],"pitfalls":["Leaving ignore_system_indexes enabled after the bounded diagnostic or recovery task.","Running the experiment on the only copy of production data.","Underestimating log, core-file, temporary-file, WAL, CPU, or connection-slot amplification.","Treating a server that merely starts or completes a query as proof that data and behavior are correct."],"references":[{"title":"PostgreSQL 19 Beta 4: ignore_system_indexes","url":"https://www.postgresql.org/docs/19/runtime-config-developer.html#GUC-IGNORE-SYSTEM-INDEXES"},{"title":"PostgreSQL 19 release notes","url":"https://www.postgresql.org/docs/19/release-19.html"}],"related":["allow_system_table_mods","ignore_checksum_failure","zero_damaged_pages","shared_buffers"],"summary":"ignore_system_indexes — Disables reading from system indexes. Observed in PG9.0–19 Beta 4; its last measured boot default is off in PG19 Beta 4, with backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA."},"enumvals":[],"first_version":"8.2","group":"Developer Options","group_slug":"developer","imported_at":"2026-09-27T17:57:31.392833+08:00","intro_commit":{},"key":"ignore_system_indexes","last_version":"20","max_val":"","min_val":"","name":"ignore_system_indexes","position":178,"present_in":["8.2","8.3","8.4","9.0","9.1","9.2","9.3","9.4","9.5","9.6","10","11","12","13","14","15","16","17","18","19","20"],"short_desc":"Ignore system indexes when reading system tables (but still update the indexes when modifying the tables).","short_desc_zh":"","source_rev":"english-manuals:147cf935527056076cc011d5cc8253452becb6378169887f030d8181633e2850","unit":"","vartype":"bool"}},"Definition":{"Collection":"guc","Key":"ignore_system_indexes","SourceDatabase":"center","Version":"18","SourceTable":"guc","SourceKey":"ignore_system_indexes","SourceRevision":"english-manuals:147cf935527056076cc011d5cc8253452becb6378169887f030d8181633e2850","Facts":{"boot_val":"off","category":"Developer Options","context":"backend","description":"Ignore system indexes when reading system tables (but still update the indexes when modifying the tables). This is useful when recovering from damaged system indexes. This parameter cannot be changed after session start.","doc":{"anchor":"GUC-IGNORE-SYSTEM-INDEXES","file":"runtime-config-developer.html","lang":"en","sha256":"f5e7e39d176c642ac0799c87669ce2f6f60fcd97d109e290860ec74c36d7ecad","slug":"18"},"documented":true,"enumvals":null,"extra_desc":"It does not prevent updating the indexes, so it is safe to use.  The worst consequence is slowness.","lang":"en","max_val":null,"metadata_version":"18","min_val":null,"name":"ignore_system_indexes","short_desc":"Disables reading from system indexes.","source":"pg-settings-source-snapshot","unit":null,"vartype":"bool"},"ManualEvidence":{"doc":{"anchor":"GUC-IGNORE-SYSTEM-INDEXES","file":"runtime-config-developer.html","lang":"en","sha256":"f5e7e39d176c642ac0799c87669ce2f6f60fcd97d109e290860ec74c36d7ecad","slug":"18"}},"MeasuredEvidence":{"metadata_version":"18"}},"Text":{"Collection":"guc","Key":"ignore_system_indexes","SourceDatabase":"center","Version":"18","Locale":"en","Title":"ignore_system_indexes","Summary":"Ignore system indexes when reading system tables (but still update the indexes when modifying the tables). This is useful when recovering from damaged system indexes. This parameter cannot be changed after session start.","BodyHTML":"\u003cp\u003eIgnore system indexes when reading system tables (but still update the indexes when modifying the tables). This is useful when recovering from damaged system indexes. This parameter cannot be changed after session start.\u003c/p\u003e","SourceRevision":"english-manuals:147cf935527056076cc011d5cc8253452becb6378169887f030d8181633e2850","ContentHash":"770abe8f7318abe1c3211617838fa900f7395b3f9ef05e3afcd004e079b9b1d5","Payload":{"description":"Ignore system indexes when reading system tables (but still update the indexes when modifying the tables). This is useful when recovering from damaged system indexes. This parameter cannot be changed after session start."}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20","8.2","8.3","8.4","9.0","9.1","9.2","9.3","9.4","9.5","9.6"],"Locales":["en"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}