{"Entry":{"collection":"guc","key":"jit_dump_bitcode","name":"jit_dump_bitcode","aliases":[],"metadata":{"baseline":false,"boot_human":"Not specified","boot_val":null,"category":"Developer Options","category_zh":"","changed_in":[],"changes":[{"documentation_changed":false,"fields":{},"from":"10","status":"added","to":"11"},{"documentation_changed":true,"fields":{},"from":"14","status":"changed","to":"15"}],"content_hash":"c0baaa1dff3b82e9f7c0b648c79f9e1d5e07de07dc34169e9e400732f24d6042","context":"","default_changed_in":[],"default_history":[{"from":"11","to":"19","value":"off"}],"editorial":{"advice":{"olap":"Long analytical runs can amplify jit_dump_bitcode's debug overhead and artifacts. Prefer standard EXPLAIN and statistics first, and isolate any developer experiment from normal users.","oltp":"Do not tune production OLTP with jit_dump_bitcode. Enable it only for a bounded reproduction with an owner, log/disk budget, rollback condition, and evidence-capture plan; restore the default immediately afterward.","small":"Keep jit_dump_bitcode at its upstream default. A small host has less spare CPU, disk, connection, and log capacity for developer instrumentation."},"mechanism":["jit_dump_bitcode writes generated LLVM IR/bitcode files inside data_directory for queries that actually run JIT. It exists to inspect and reproduce JIT compiler behavior.","It does not activate JIT and produces nothing when no query crosses the JIT gates. Generated artifacts can accumulate, consume disk, and contain details derived from executed expressions.","Only a tightly controlled debugging session should enable it; files require explicit collection and cleanup. Its superuser context permits an authorized session change without a server restart."],"pitfalls":["Leaving jit_dump_bitcode 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: jit_dump_bitcode","url":"https://www.postgresql.org/docs/19/runtime-config-developer.html#GUC-JIT-DUMP-BITCODE"},{"title":"PostgreSQL 19 release notes","url":"https://www.postgresql.org/docs/19/release-19.html"}],"related":["jit","jit_above_cost","jit_debugging_support","jit_profiling_support","data_directory"],"summary":"jit_dump_bitcode — Write out LLVM bitcode to facilitate JIT debugging. Observed in PG11–19 Beta 4; its last measured boot default is off in PG19 Beta 4, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA."},"enumvals":[],"first_version":"11","group":"Developer Options","group_slug":"developer","imported_at":"2026-09-27T17:57:31.42918+08:00","intro_commit":{"authored_at":"2018-03-22T11:05:22-07:00","discussion":["https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de"],"hash":"b96d550eb03cfdb000def70912ec840dbe7f67da","subject":"Support for optimizing and emitting code in LLVM JIT provider.","url":"https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=b96d550eb03cfdb000def70912ec840dbe7f67da"},"key":"jit_dump_bitcode","last_version":"20","max_val":"","min_val":"","name":"jit_dump_bitcode","position":193,"present_in":["11","12","13","14","15","16","17","18","19","20"],"short_desc":"Writes the generated LLVM IR out to the file system, inside data_directory.","short_desc_zh":"","source_rev":"english-manuals:b64c5a5bb5201adc4a6df5f7e46b65b5f002f939fdb8da6fa9250d722f8552aa","unit":"","vartype":"bool"}},"Definition":{"Collection":"guc","Key":"jit_dump_bitcode","SourceDatabase":"center","Version":"18","SourceTable":"guc","SourceKey":"jit_dump_bitcode","SourceRevision":"english-manuals:b64c5a5bb5201adc4a6df5f7e46b65b5f002f939fdb8da6fa9250d722f8552aa","Facts":{"boot_val":"off","category":"Developer Options","context":"superuser","description":"Writes the generated LLVM IR out to the file system, inside data_directory. This is only useful for working on the internals of the JIT implementation. The default setting is off. Only superusers and users with the appropriate SET privilege can change this setting.","doc":{"anchor":"GUC-JIT-DUMP-BITCODE","file":"runtime-config-developer.html","lang":"en","sha256":"f5e7e39d176c642ac0799c87669ce2f6f60fcd97d109e290860ec74c36d7ecad","slug":"18"},"documented":true,"enumvals":null,"extra_desc":null,"lang":"en","max_val":null,"metadata_version":"18","min_val":null,"name":"jit_dump_bitcode","short_desc":"Write out LLVM bitcode to facilitate JIT debugging.","source":"pg-settings-source-snapshot","unit":null,"vartype":"bool"},"ManualEvidence":{"doc":{"anchor":"GUC-JIT-DUMP-BITCODE","file":"runtime-config-developer.html","lang":"en","sha256":"f5e7e39d176c642ac0799c87669ce2f6f60fcd97d109e290860ec74c36d7ecad","slug":"18"}},"MeasuredEvidence":{"metadata_version":"18"}},"Text":{"Collection":"guc","Key":"jit_dump_bitcode","SourceDatabase":"pgweb","Version":"18","Locale":"zh-Hans","Title":"jit_dump_bitcode","Summary":"","BodyHTML":"\u003cp\u003e将生成的\u003cspan\u003eLLVM\u003c/span\u003e IR写入文件系统，位于\u003ca href=\"/docs/18/runtime-config-file-locations.html#GUC-DATA-DIRECTORY\" rel=\"nofollow\"\u003edata_directory\u003c/a\u003e内。这仅对开发 JIT 的内部实现有用。默认设置为\u003ccode\u003eoff\u003c/code\u003e。只有超级用户和具有适当\u003ccode\u003eSET\u003c/code\u003e权限的用户才能更改此设置。\u003c/p\u003e","SourceRevision":"2026-09-11@29c86d9","ContentHash":"672b5b698192c1199a51866cc838048e9f9add532fb9fa359854e85c3525bca7","Payload":{"carried_from":"","carry_reason":"","doc_html":"\u003cp\u003e将生成的\u003cspan class=\"productname\"\u003eLLVM\u003c/span\u003e IR写入文件系统，位于\u003ca href=\"/docs/18/runtime-config-file-locations.html#GUC-DATA-DIRECTORY\"\u003edata_directory\u003c/a\u003e内。这仅对开发 JIT 的内部实现有用。默认设置为\u003ccode class=\"literal\"\u003eoff\u003c/code\u003e。只有超级用户和具有适当\u003ccode class=\"literal\"\u003eSET\u003c/code\u003e权限的用户才能更改此设置。\u003c/p\u003e","doc_same_as":""}},"RequestedLocale":"zh-Hans","Fallback":false,"Versions":["11","12","13","14","15","16","17","18","19","20"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}