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Chapter 34. Large Objects

Table of Contents

34.1. Introduction
34.2. Implementation Features
34.3. Client Interfaces
34.3.1. Creating a Large Object
34.3.2. Importing a Large Object
34.3.3. Exporting a Large Object
34.3.4. Opening an Existing Large Object
34.3.5. Writing Data to a Large Object
34.3.6. Reading Data from a Large Object
34.3.7. Seeking in a Large Object
34.3.8. Obtaining the Seek Position of a Large Object
34.3.9. Truncating a Large Object
34.3.10. Closing a Large Object Descriptor
34.3.11. Removing a Large Object
34.4. Server-Side Functions
34.5. 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.