Tablespaces(2)

tbs Tablespaces(2)#

In PostgreSQL, tablespaces define the physical locations on disk where database objects are stored. The label Tablespaces (2) in pgAdmin indicates that two default tablespaces are currently available on the PostgreSQL server.

A tablespace is a physical location on disk where PostgreSQL stores database objects such as tables and indexes.

By default, PostgreSQL uses built-in tablespaces, but it also allows custom ones.

Why does pgAdmin show Tablespaces (2)?#

In pgAdmin, the number in parentheses shows the count of tablespaces available on the server.

Tablespaces (2)
├── pg_default
└── pg_global
This means:

  • PostgreSQL currently has 2 tablespaces

  • Both are system-defined

  • No custom tablespaces have been created yet

What are the default tablespaces?#

1️⃣ pg_default

  • Stores user data

  • Default location for:

  • Tables

  • Indexes

  • Schemas

    • Used unless another tablespace is specified

Most of your databases live here.

2️⃣ pg_global

  • Stores global system data

  • Shared across all databases

  • Contains:

  • Roles (users)

  • System catalogs

  • Global metadata

You usually never touch this directly.

Why PostgreSQL uses tablespaces

Tablespaces allow you to:

  • Control where data is stored

  • Separate data across disks

  • Improve performance

  • Manage storage efficiently

Example use cases:

  • Fast SSD for indexes

  • Large HDD for archival tables

  • Separate disks for different workloads

Real-world analogy

Think of tablespaces like:

  • Folders on a hard drive

  • PostgreSQL decides which folder stores which data

But PostgreSQL manages everything internally.

Tablespaces vs Databases

Concept

Purpose

Database

Logical container for data

Schema

Namespace inside a database

Tablespace

Physical storage location

Tablespaces are about disk, not structure.

Note

📝 One-line summary

Tablespaces control where PostgreSQL stores database data physically on disk.

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