Chapter 30. Large Objects

Table of Contents
30.1. Introduction
30.2. Implementation Features
30.3. Client Interfaces
30.3.1. Creating a Large Object
30.3.2. Importing a Large Object
30.3.3. Exporting a Large Object
30.3.4. Opening an Existing Large Object
30.3.5. Writing Data to a Large Object
30.3.6. Reading Data from a Large Object
30.3.7. Seeking in a Large Object
30.3.8. Obtaining the Seek Position of a Large Object
30.3.9. Closing a Large Object Descriptor
30.3.10. Removing a Large Object
30.4. Server-Side Functions
30.5. Example Program

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 may use the large object interface internally to provide generic support for large values. This is not described here.