FOR NO KEY UPDATE

commands

map[label:SELECT FOR NO KEY UPDATE note:Lock selected rows, with ROW SHARE on the target table. NOWAIT and SKIP LOCKED affect waiting, not mode compatibility. slug:select source:map[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] source_url:https://www.postgresql.org/docs/18/explicit-locking.html variant:dc13a30028da], map[label:UPDATE (non-key update) note:UPDATE uses this mode when it does not require FOR UPDATE. Key columns are columns of a unique index usable by a foreign key; partial and expression indexes do not qualify. slug:update source:map[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] source_url:https://www.postgresql.org/docs/18/explicit-locking.html variant:ff82a8ae4e60], map[label:MERGE … WHEN MATCHED THEN UPDATE (non-key) note:The UPDATE branch actually runs and does not need FOR UPDATE. Other MERGE actions can require different row locks. slug:merge source:map[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] source_url:https://www.postgresql.org/docs/18/explicit-locking.html variant:85e4fea63221], map[label:INSERT … ON CONFLICT DO UPDATE (non-key) note:Lock the existing conflicting row for UPDATE, even when the DO UPDATE WHERE condition excludes the update. Key-column changes determine the mode. slug:insert source:map[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] source_url:https://www.postgresql.org/docs/18/sql-insert.html variant:22d6f52ccf90]

provenance

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summary

Behaves similarly to FOR UPDATE, except that the lock acquired is weaker: this lock will not block SELECT FOR KEY SHARE commands that attempt to acquire a lock on the same rows. This lock mode is also acquired by any UPDATE that does not acquire a FOR UPDATE lock.