---
title: "Introduction"
id: lo-intro
pg_version: "20devel"
---

<a id="lo-intro"></a>

## 33.1. Introduction

All large objects are stored in a single system table named [pg_largeobject](catalog-pg-largeobject.md). Each large object also has an entry in the system table [pg_largeobject_metadata](catalog-pg-largeobject-metadata.md). Large objects can be created, modified, and deleted using a read/write API that is similar to standard operations on files. 

PostgreSQL also supports a storage system called ["TOAST"](storage-toast.md), which automatically stores values larger than a single database page into a secondary storage area per table. This makes the large object facility partially obsolete. One remaining advantage of the large object facility is that it allows values up to 4 TB in size, whereas TOASTed fields can be at most 1 GB. Also, reading and updating portions of a large object can be done efficiently, while most operations on a TOASTed field will read or write the whole value as a unit.