> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/15/client-interfaces/34.-large-objects/34.1.-introduction.md).

# 35.1. Introduction

## 35.1. Introduction

All large objects are stored in a single system table named [`pg_largeobject`](/15/internals/system-catalogs/pg_largeobject.md). Each large object also has an entry in the system table [`pg_largeobject_metadata`](/15/internals/system-catalogs/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”](/15/internals/database-physical-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.

***

原文：[PostgreSQL 15.19 Documentation](/15/client-interfaces/34.-large-objects/34.1.-introduction.md)（英文原文，待翻譯）


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