PUBLIC MARKS from Spone with tag locking

Locking is a very important part of PostgreSQL (as well as most of other modern RDBMS). It should be familiar to every developer of DB applications (especially to those who are working on highly concurrent code). Locking is mostly addressed and researched when some problem arises. In most cases, these problems relate to deadlock or data inconsistency due to misunderstanding how locking works in Postgres. Despite its importance, locking mechanism in Postgres is poorly documented and doesn't even work as expected in some cases (as documentation suggests). I will hereby try to present everything we should know in order to work with Postgres, having in mind locking mechanisms as well as faster resolution of locking issues.