MyDB

mydb MyDB#

MyDB represents a user-created PostgreSQL database. This is where real application data lives and where developers work most of the time.

Unlike system databases (such as postgres), a user database is designed to store: - Application tables - Business logic - Schemas - Extensions - Metadata related to the application

You can think of MyDB as a workspace inside the PostgreSQL server.

What is MyDB conceptually?#

A PostgreSQL server can host multiple databases, and MyDB is one of them.

Each database: - Is logically isolated - Has its own schemas - Has its own objects (tables, views, functions, etc.) - Cannot directly access objects in another database

This isolation is intentional and provides: - Security - Stability - Clear boundaries between applications

What lives inside MyDB?#

Inside a database like MyDB, PostgreSQL organizes objects into categories.

These categories are exactly what you see below in the sidebar:

  • Casts – Rules for converting one data type into another

  • Catalogs – System tables describing database metadata

  • Event Triggers – Hooks that react to DDL events

  • Extensions – Optional PostgreSQL features (e.g. uuid-ossp, postgis)

  • Foreign Data Wrappers – Access external data sources

  • Languages – Procedural languages (PL/pgSQL, PL/Python, etc.)

  • Publications – Objects used for logical replication

  • Schemas – Namespaces that organize tables and other objects

  • Subscriptions – Logical replication subscribers

Each of these sections represents a different responsibility inside the database.

Why PostgreSQL separates these objects#

PostgreSQL follows a layered architecture:

Server
  └── Database (MyDB)
        ├── Schemas
        │     └── Tables / Views / Functions
        ├── Extensions
        ├── Languages
        ├── Replication Objects
        └── System Metadata

This separation allows PostgreSQL to: - Scale cleanly - Enforce permissions - Keep system data safe - Allow advanced features like replication and FDW

How this maps to pgAdmin#

In pgAdmin, when you expand MyDB, you see the same structure:

  • MyDB - Casts - Catalogs - Event Triggers - Extensions - Schemas - …

What you should focus on first#

As a developer, you will mostly work with:

  1. Schemas

  2. Tables

  3. Indexes

  4. Extensions

  5. Functions

The other sections exist mainly for: - Administration - Optimization - Replication - Advanced PostgreSQL features

Summary#

Note

MyDB is a logical container inside a PostgreSQL server that holds all application data, schemas, and database-level objects.

Contents