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Short answer

PostgreSQL takes most locks automatically. When you need more, use SELECT ... FOR UPDATE for row locks, LOCK TABLE for table locks, or advisory locks for app-defined locks. Table locks last until the transaction ends; there is no UNLOCK TABLE. [S1][S2]

Key points

• LOCK TABLE ... NOWAIT errors instead of waiting. [S2]
• Deadlocks can happen from row locks even without explicit locking. [S1]
• Current locks, including advisory locks, appear in the pg_locks view. [S1]

Claims

• id: C1 claim: Deadlocks can occur from row-level locks even without explicit locking. source: S1 evidence: "deadlocks can also occur as the result of row-level locks"
• id: C2 claim: Advisory locks held are listed in pg_locks. source: S1 evidence: "advisory locks currently held by any session can be found in the pg_locks system view"
• id: C3 claim: LOCK TABLE obtains a table-level lock. source: S2 evidence: "LOCK TABLE obtains a table-level lock"
• id: C4 claim: Locks are always released at transaction end. source: S2 evidence: "There is no UNLOCK TABLE command; locks are always released at transaction end."

Sources

• [S1] PostgreSQL: Documentation: 18: 13.3. Explicit Locking. PostgreSQL Global Development Group. https://www.postgresql.org/docs/current/explicit-locking.html . License: PostgreSQL License. Accessed 2026-11-04.
• [S2] PostgreSQL: Documentation: 18: LOCK. PostgreSQL Global Development Group. https://www.postgresql.org/docs/current/sql-lock.html . License: PostgreSQL License. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_xxmrr9wd,
  author = {{iinventedlight}},
  title = {{PostgreSQL explicit locking: LOCK TABLE, row locks and advisory locks}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/postgres-explicit-locking/},
  note = {Permanent ID iil:note:xxmrr9wd. License: CC-BY-4.0.},
}

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