{"Entry":{"collection":"guc","key":"max_index_keys","name":"max_index_keys","aliases":[],"metadata":{"baseline":false,"boot_human":"Not specified","boot_val":null,"category":"Preset Options","category_zh":"","changed_in":[],"changes":[{"documentation_changed":false,"fields":{},"from":"7.4","status":"added","to":"8.0"},{"documentation_changed":true,"fields":{},"from":"8.0","status":"changed","to":"8.1"},{"documentation_changed":true,"fields":{},"from":"8.1","status":"changed","to":"8.2"}],"content_hash":"16aab0daa29c3072d03669a7956b8103d7b21314457e6e97438f33b6bd802aaa","context":"","default_changed_in":[],"default_history":[{"from":"9.0","to":"19","value":"32"}],"editorial":{"advice":{"olap":"Not tunable. Use max_index_keys to verify format, build, or resource assumptions on analytical nodes and keep every read/write candidate compatible.","oltp":"Not tunable. Record max_index_keys as a deployment/capability fact; if it is unexpected, fix the binary, initdb, or database-creation process rather than trying SET.","small":"Not tunable. Preserve it in inventory and incident reports; do not custom-build or rebuild merely to change it without a demonstrated compatibility need."},"mechanism":["Shows the maximum number of index keys. It is read-only and cannot be changed with SET or configuration-file edits.","It exposes the INDEX_MAX_KEYS build limit on index attributes, including key and INCLUDE columns where applicable.","Interpret it with max_function_args, max_identifier_length, block_size. Applications and operations tooling may read max_index_keys for capability or environment detection, but cannot SET it; cross-cluster comparisons must account for build, initdb, and current-database differences."],"pitfalls":["Trying to change read-only max_index_keys with SET or a configuration file.","Assuming every cluster, database, or vendor build reports the same value.","Ignoring the value in file-format or feature-compatibility checks.","Treating reported metadata as a performance target instead of an environment fact."],"references":[{"title":"PostgreSQL 19 Beta 4: max_index_keys","url":"https://www.postgresql.org/docs/19/runtime-config-preset.html#GUC-MAX-INDEX-KEYS"},{"title":"PostgreSQL 19 release notes","url":"https://www.postgresql.org/docs/19/release-19.html"}],"related":["max_function_args","max_identifier_length","block_size","server_version_num","data_checksums","data_directory_mode"],"summary":"max_index_keys — Shows the maximum number of index keys. Observed in PG9.0–19 Beta 4; its last measured boot default is 32 in PG19 Beta 4, with internal context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA."},"enumvals":[],"first_version":"8.0","group":"Preset Options","group_slug":"preset","imported_at":"2026-09-27T17:57:31.697295+08:00","intro_commit":{},"key":"max_index_keys","last_version":"20","max_val":"","min_val":"","name":"max_index_keys","position":269,"present_in":["8.0","8.1","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":"Reports the maximum number of index keys.","short_desc_zh":"","source_rev":"english-manuals:71064903dec4f0420c6960bef2e87dfea33694489a5a720ca56e43b64acf5e46","unit":"","vartype":"integer"}},"Definition":{"Collection":"guc","Key":"max_index_keys","SourceDatabase":"center","Version":"18","SourceTable":"guc","SourceKey":"max_index_keys","SourceRevision":"english-manuals:71064903dec4f0420c6960bef2e87dfea33694489a5a720ca56e43b64acf5e46","Facts":{"boot_val":"32","category":"Preset Options","context":"internal","description":"Reports the maximum number of index keys. It is determined by the value of INDEX_MAX_KEYS when building the server. The default value is 32 keys.","doc":{"anchor":"GUC-MAX-INDEX-KEYS","file":"runtime-config-preset.html","lang":"en","sha256":"4dbfec727b9cee838adefb8a766217748d91ab90190b452a58cec737459582ce","slug":"18"},"documented":true,"enumvals":null,"extra_desc":null,"lang":"en","max_val":"32","metadata_version":"18","min_val":"32","name":"max_index_keys","short_desc":"Shows the maximum number of index keys.","source":"pg-settings-source-snapshot","unit":null,"vartype":"integer"},"ManualEvidence":{"doc":{"anchor":"GUC-MAX-INDEX-KEYS","file":"runtime-config-preset.html","lang":"en","sha256":"4dbfec727b9cee838adefb8a766217748d91ab90190b452a58cec737459582ce","slug":"18"}},"MeasuredEvidence":{"metadata_version":"18"}},"Text":{"Collection":"guc","Key":"max_index_keys","SourceDatabase":"center","Version":"18","Locale":"en","Title":"max_index_keys","Summary":"Reports the maximum number of index keys. It is determined by the value of INDEX_MAX_KEYS when building the server. The default value is 32 keys.","BodyHTML":"\u003cp\u003eReports the maximum number of index keys. It is determined by the value of INDEX_MAX_KEYS when building the server. The default value is 32 keys.\u003c/p\u003e","SourceRevision":"english-manuals:71064903dec4f0420c6960bef2e87dfea33694489a5a720ca56e43b64acf5e46","ContentHash":"d443bb25195247589dbf27db1be2f931d9b5d874332baa7b0e1070eacbcea931","Payload":{"description":"Reports the maximum number of index keys. It is determined by the value of INDEX_MAX_KEYS when building the server. The default value is 32 keys."}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20","8.0","8.1","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}