Documentazione di PostgreSQL 9.0 > Client Interfaces > Large Objects
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32. Large Objects

PostgreSQL™ has a large object facility, which provides stream-style access to user data that is stored in a special large-object structure. Streaming access is useful when working with data values that are too large to manipulate conveniently as a whole.

This chapter describes the implementation and the programming and query language interfaces to PostgreSQL™ large object data. We use the libpq C library for the examples in this chapter, but most programming interfaces native to PostgreSQL™ support equivalent functionality. Other interfaces might use the large object interface internally to provide generic support for large values. This is not described here.

32.1. Introduction

All large objects are placed in a single system table called pg_largeobject. PostgreSQL™ also supports a storage system called «TOAST» that 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 2 GB in size, whereas TOASTed fields can be at most 1 GB. Also, large objects can be randomly modified using a read/write API that is more efficient than performing such operations using TOAST.

Documentazione di PostgreSQL 9.0 > Client Interfaces > Large Objects
PrecedenteExample ProgramsImplementation FeaturesSuccessivo