---
title: "Lock — Database Glossary | Xata"
description: "A mechanism preventing concurrent access conflicts. PostgreSQL uses multiple lock types: row-level (shared/exclusive), table-level (eight modes from ACC..."
source: "https://xata.io/glossary/lock"
---

# Lock

Transactions

A mechanism preventing concurrent access conflicts. PostgreSQL uses multiple lock types: row-level (shared/exclusive), table-level (eight modes from ACCESS SHARE to ACCESS EXCLUSIVE), advisory, and predicate locks.

Related terms

[Deadlock](/glossary/deadlock)[Advisory Lock](/glossary/advisory-lock)

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