{"Entry":{"collection":"lock","key":"for-key-share","name":"FOR KEY SHARE","aliases":[],"metadata":{"abbrev":"FKS","content_hash":"9f7f37ba2035d6cfce663aa8fd8a0811882a47d3746bd9db248107a4450fa39a","imported_at":"2026-09-27T17:58:01.265938+08:00","name":"FOR KEY SHARE","name_zh":"FOR KEY SHARE","position":8,"scope":"row","slug":"for-key-share","source_rev":"10:f4e8f137bfb08a664c8288824c1e36b5143ac875;11:170e416034ec0231d9e9238f2577eeb76ca8d181;12:3f302f0ed06f69c5ebd33d4df95895323a3cbef6;13:05f6c9ec2c475fae8fdd56ae40bd01afcf70d1f2;14:fba35c7c28a567839faba867db0808564c0a66db;15:0351991b8e7c7b64382e2f30ce581a8f276590a6;16:dcc37b7099a9f3cf2c75167d8dc92e75f96bc1fa;17:163288afd32a448244c8df75b3c33181aadd7f20;18:753057e340da8f22e57c9a409ea7a235fd6a46bd;19:b73d13c32c834a2c8e1c60cb92f79530376cedf1;20:2c10c2ce4d7bcd57543a49ab402af02a39724e0a","summary":"Behaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE."}},"Definition":{"Collection":"lock","Key":"for-key-share","SourceDatabase":"center","Version":"18","SourceTable":"lock_mode","SourceKey":"for-key-share","SourceRevision":"10:f4e8f137bfb08a664c8288824c1e36b5143ac875;11:170e416034ec0231d9e9238f2577eeb76ca8d181;12:3f302f0ed06f69c5ebd33d4df95895323a3cbef6;13:05f6c9ec2c475fae8fdd56ae40bd01afcf70d1f2;14:fba35c7c28a567839faba867db0808564c0a66db;15:0351991b8e7c7b64382e2f30ce581a8f276590a6;16:dcc37b7099a9f3cf2c75167d8dc92e75f96bc1fa;17:163288afd32a448244c8df75b3c33181aadd7f20;18:753057e340da8f22e57c9a409ea7a235fd6a46bd;19:b73d13c32c834a2c8e1c60cb92f79530376cedf1;20:2c10c2ce4d7bcd57543a49ab402af02a39724e0a","Facts":{"commands":[{"label":"SELECT FOR KEY SHARE","note":"Lock selected rows, with ROW SHARE on the target table. 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Cascading actions require their own UPDATE or DELETE locks.","slug":"insert","source":{"kind":"source","path":"src/backend/utils/adt/ri_triggers.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"a3fed49fbda88fe0fe5bcf35eb019fced28596ae4046233f2acb2eb9f90ab1da","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c"},"source_url":"https://github.com/postgres/postgres/blob/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c","variant":"ffddc0fc16b6"},{"label":"UPDATE (foreign-key check)","note":"Checking a non-null foreign key locks matching rows in the referenced table FOR KEY SHARE. The check can run immediately or be deferred. Cascading actions require their own UPDATE or DELETE locks.","slug":"update","source":{"kind":"source","path":"src/backend/utils/adt/ri_triggers.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"a3fed49fbda88fe0fe5bcf35eb019fced28596ae4046233f2acb2eb9f90ab1da","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c"},"source_url":"https://github.com/postgres/postgres/blob/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c","variant":"65d8638ef74c"},{"label":"COPY … FROM (foreign-key check)","note":"Checking a non-null foreign key locks matching rows in the referenced table FOR KEY SHARE. The check can run immediately or be deferred. 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Cascading actions require their own UPDATE or DELETE locks.","slug":"merge","source":{"kind":"source","path":"src/backend/utils/adt/ri_triggers.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"a3fed49fbda88fe0fe5bcf35eb019fced28596ae4046233f2acb2eb9f90ab1da","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c"},"source_url":"https://github.com/postgres/postgres/blob/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c","variant":"e00dfdc184d6"}],"conflicts":["for-update"],"description":["Behaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE."],"provenance":{"doc_slug":"18","fetched_at":"2026-09-27T09:39:42+00:00","label":"18","major":"18","official_url":"https://www.postgresql.org/docs/18/explicit-locking.html","ref":"REL_18_STABLE","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sources":[{"kind":"command-documentation","path":"doc/src/sgml/ref/alter_index.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"746cd43287186dfbfa6acf77fd5c6713e66919653fb00af5476a0baa65988e7a","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/alter_index.sgml"},{"kind":"command-documentation","path":"doc/src/sgml/ref/alter_table.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"10436673fa2f093bdf51986a06d22dd748a9bb003bcd5517db2a65fba569a3c9","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/alter_table.sgml"},{"kind":"command-documentation","path":"doc/src/sgml/ref/comment.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"d0048329d237192696d7ccb9471aba4137d943556fdb770e2ffb3cf6c511c18f","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/comment.sgml"},{"kind":"source","path":"src/backend/commands/copy.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"f50ecc1531109fc172d841d461e209cef611f3d017ef4184034c39e128deabbe","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/commands/copy.c"},{"kind":"command-documentation","path":"doc/src/sgml/ref/create_index.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"3698f11c6f447d127e4624a1a845dee4d5146b8337ddc6d895a7962e676717f8","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/create_index.sgml"},{"kind":"source","path":"src/backend/access/heap/heapam.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"bca2ca0746a1862016bdb416b8482441a7b16360f71afe5e4abf6dbae0fa0c72","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/access/heap/heapam.c"},{"kind":"source","path":"src/backend/catalog/index.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"98a4156a5c21ae856a3b583b633cdeb578a5b69910386c9f166d69fcb04ba2d0","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/catalog/index.c"},{"kind":"command-documentation","path":"doc/src/sgml/ref/insert.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"f93403779fb1d980cd5995a1e2741bbdae8404584407610f9aba33ec4724a39f","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/insert.sgml"},{"kind":"source","path":"src/backend/storage/lmgr/lock.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"e7f43560bf6a8417ff46991238084b6edeb44a995b87670ed1f7fa6f1515276b","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/storage/lmgr/lock.c"},{"kind":"documentation","path":"doc/src/sgml/mvcc.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"4b7bf77ee0af4b86052330ff2421d567df3604b75fe7d4f522bec84fdea87340","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/mvcc.sgml"},{"kind":"command-documentation","path":"doc/src/sgml/ref/reindex.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"5e889d6e1d9b09d5f9cd3f7086ca13f540da0fe8262cdd8a9037ce9aa6f1dfdf","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/reindex.sgml"},{"kind":"source","path":"src/backend/utils/adt/ri_triggers.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"a3fed49fbda88fe0fe5bcf35eb019fced28596ae4046233f2acb2eb9f90ab1da","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/utils/adt/ri_triggers.c"},{"kind":"source","path":"src/backend/commands/tablecmds.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"df8817816f893e73d5648fea169e222ba33320e5b24bf755b424b29098f4e7da","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/commands/tablecmds.c"},{"kind":"command-documentation","path":"doc/src/sgml/ref/vacuum.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"80ca5592cda7b74938385f84f09faac33574374c1a05d605a2d55982e4cf1bbf","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/ref/vacuum.sgml"},{"kind":"source","path":"src/backend/access/heap/vacuumlazy.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"90932e3b1a7b57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similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE."},"ManualEvidence":{"sources":[{"kind":"documentation","path":"doc/src/sgml/mvcc.sgml","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"4b7bf77ee0af4b86052330ff2421d567df3604b75fe7d4f522bec84fdea87340","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/doc/src/sgml/mvcc.sgml"},{"kind":"source","path":"src/backend/storage/lmgr/lock.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"e7f43560bf6a8417ff46991238084b6edeb44a995b87670ed1f7fa6f1515276b","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/storage/lmgr/lock.c"},{"kind":"source","path":"src/backend/access/heap/heapam.c","revision":"753057e340da8f22e57c9a409ea7a235fd6a46bd","sha256":"bca2ca0746a1862016bdb416b8482441a7b16360f71afe5e4abf6dbae0fa0c72","url":"https://raw.githubusercontent.com/postgres/postgres/753057e340da8f22e57c9a409ea7a235fd6a46bd/src/backend/access/heap/heapam.c"}]},"MeasuredEvidence":{}},"Text":{"Collection":"lock","Key":"for-key-share","SourceDatabase":"center","Version":"18","Locale":"en","Title":"FOR KEY SHARE","Summary":"Behaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE.","BodyHTML":"\u003cp\u003eBehaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE.\u003c/p\u003e","SourceRevision":"10:f4e8f137bfb08a664c8288824c1e36b5143ac875;11:170e416034ec0231d9e9238f2577eeb76ca8d181;12:3f302f0ed06f69c5ebd33d4df95895323a3cbef6;13:05f6c9ec2c475fae8fdd56ae40bd01afcf70d1f2;14:fba35c7c28a567839faba867db0808564c0a66db;15:0351991b8e7c7b64382e2f30ce581a8f276590a6;16:dcc37b7099a9f3cf2c75167d8dc92e75f96bc1fa;17:163288afd32a448244c8df75b3c33181aadd7f20;18:753057e340da8f22e57c9a409ea7a235fd6a46bd;19:b73d13c32c834a2c8e1c60cb92f79530376cedf1;20:2c10c2ce4d7bcd57543a49ab402af02a39724e0a","ContentHash":"be03394c07efdf73378538f6b0668238720f1fd444b110294251bb7670cbec23","Payload":{"description":["Behaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE."]}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20"],"Locales":["en"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}