Whenever you run a command or a query on a table, you take a lock on the table.The primary purpose of table-level locks is to block reads and/or writes when changes to the underlying table structure are made during DDL commands such as .
Armed with this understanding of the enemy and how it relates to your application, youll be much better able to avoid disaster. Scope The breadth and depth of this topic necessitates that scope be constrained.
The scope of this paper has been chosen with the following considerations in mind: There are also many types of locks that can occur such shared locks, exclusive locks, transaction locks, DML locks, and backup-recovery locks.
Atomicity ensures that either all of these actions occur or none at all.
2.1.2 Consistency Consistency means that transactions always take the database from one consistent state to another.
However, this paper will focus on one specific type of locking that I will call "transactional locking".
2.1 ACID Properties of Transactions Most of what were calling transactional locking relates to the ability of a database management system (DBMS) to ensure reliable transactions that adhere to these ACID properties.At Citus Data, we engineers take an active role in helping our customers scale out their Postgres database, be it for migrating an existing application or building a new application from scratch.This means we help you with distributing your relational data model—and also with getting the most out of Postgres.If you’re using the Citus extension to Postgres to shard database tables across multiple nodes, one more thing to take into consideration is that queries might get blocked on row-level locks on one of the shards on a distributed Citus worker node—and if that happens, then those queries would not show up in to get more information such as how long the query was running.Locking is one of the mechanisms that Postgres uses to safely implement concurrent ACID transactions.Transactions run concurrently until they try to acquire a conflicting lock, for example when they update the same row.