An understanding of PostgreSQL locking is important to build scalable applications and avoid downtime. Modern computers and servers have many CPU cores and it’s possible to execute multiple queries in parallel. Databases containing many consistent structures with changes made by queries or background processes running in parallel could crash a database or even corrupt data. [&]

https://www.percona.com/blog/2018/10/16/postgresql-locking-part-1-row-locks/