Tag: visibility check

Enterprise PostgreSQL Solutions

A Deeper Look Inside PostgreSQL Visibility Check Mechanism

What is Visibility? Simply put, the visibility refers to whether a row of data (Heap Tuple by default) should be displayed to the user in certain states, backend processes, or transactions. For example, MVCC (Multi-Version Concurrency Control) is a method in which each write operation creates a “new version” of the data while retaining the…
Read more

Understand PG’s MVCC Visibility Basic Check Rules

1. Introduction PostgreSQL’s MultiVersion Concurrency Control (MVCC) is an “advanced technique for improving database performance in a multi-user environment” according to Vadim Mikheev. This technique requires multiple “versions” of the same data tuple exist in the system governed by snapshots taken during different time periods. In other words, under such technique, it is PG’s responsibility…
Read more