Chapter 35. Large Objects

Table of Contents

35.1. Introduction
35.2. Implementation Features
35.3. Client Interfaces
35.3.1. Creating a Large Object
35.3.2. Importing a Large Object
35.3.3. Exporting a Large Object
35.3.4. Opening an Existing Large Object
35.3.5. Writing Data to a Large Object
35.3.6. Reading Data from a Large Object
35.3.7. Seeking in a Large Object
35.3.8. Obtaining the Seek Position of a Large Object
35.3.9. Truncating a Large Object
35.3.10. Closing a Large Object Descriptor
35.3.11. Removing a Large Object
35.4. Server-Side Functions
35.5. 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 might use the large object interface internally to provide generic support for large values. This is not described here.