In PostgreSQL, being able to authenticate as a user does not automatically mean you can connect to a database. Connection permission is a separate, explicit check—and if you’ve ever wondered why a valid user suddenly gets: FATAL: permission denied for…
PostgreSQL exposes object-level permissions through Access Control Lists (ACLs). While the SQL GRANT and REVOKE commands are familiar to most administrators, the internal ACL representation—especially when viewed through psql’s \dp command—can be confusing at first glance. One of the most…
PostgreSQL offers a sophisticated and layered security model that precisely controls how users authenticate and access data. To properly secure a PostgreSQL cluster, it is critical to understand the difference between two often-confused concepts: Although both are required for a…
If you’ve worked with PostgreSQL long enough, you’ve probably seen something like this: And the result looked like: At first glance, $user feels mysterious. Is it a variable? A placeholder? A real schema? Let’s unpack what $user actually means, how…
If you’ve worked with PostgreSQL long enough, you’ve probably heard this sentence before: “PostgreSQL is safe because everything is written to WAL.” It sounds reasonable. It feels reassuring. And it’s only half true. This misunderstanding — confusing WAL with actual…
Introduction One of the most confusing aspects of PostgreSQL’s logical replication is understanding the relationship between WHERE conditions in your SQL statements and REPLICA IDENTITY configuration. Many developers mistakenly believe that: “If I use a WHERE clause with specific conditions,…
Introduction pglogical is a powerful PostgreSQL extension that provides logical streaming replication using a publish/subscribe model. Developed by 2ndQuadrant (now part of EnterpriseDB), it enables selective replication of tables, columns, and rows between PostgreSQL instances, offering flexibility that traditional physical…
Introduction to Redis What is Redis? Redis (Remote Dictionary Server) is an open-source, in-memory data structure store that can be used as a database, cache, and message broker. It’s known for its exceptional speed, simplicity, and versatility. Key Characteristics Common…
Ever had that sinking feeling when you see your server’s disk space slowly vanishing? You investigate, and the trail leads you to a directory named pg_wal, filled with countless files. If this sounds familiar, you’re in the right place. Before…
Getting started with a new database system can feel like exploring a new city. You need a map to find your way around and locate key landmarks. In PostgreSQL, one of the first “landmarks” you’ll want to find is your…
