Chapter 34. libpq — C Library

Table of Contents

34.1. Database Connection Control Functions
34.1.1. Connection Strings
34.1.2. Parameter Key Words
34.2. Connection Status Functions
34.3. Command Execution Functions
34.3.1. Main Functions
34.3.2. Retrieving Query Result Information
34.3.3. Retrieving Other Result Information
34.3.4. Escaping Strings for Inclusion in SQL Commands
34.4. Asynchronous Command Processing
34.5. Retrieving Query Results Row-by-Row
34.6. Canceling Queries in Progress
34.7. The Fast-Path Interface
34.8. Asynchronous Notification
34.9. Functions Associated with the COPY Command
34.9.1. Functions for Sending COPY Data
34.9.2. Functions for Receiving COPY Data
34.9.3. Obsolete Functions for COPY
34.10. Control Functions
34.11. Miscellaneous Functions
34.12. Notice Processing
34.13. Event System
34.13.1. Event Types
34.13.2. Event Callback Procedure
34.13.3. Event Support Functions
34.13.4. Event Example
34.14. Environment Variables
34.15. The Password File
34.16. The Connection Service File
34.17. LDAP Lookup of Connection Parameters
34.18. SSL Support
34.18.1. Client Verification of Server Certificates
34.18.2. Client Certificates
34.18.3. Protection Provided in Different Modes
34.18.4. SSL Client File Usage
34.18.5. SSL Library Initialization
34.19. Behavior in Threaded Programs
34.20. Building libpq Programs
34.21. Example Programs

libpq is the C application programmer's interface to PostgreSQL. libpq is a set of library functions that allow client programs to pass queries to the PostgreSQL backend server and to receive the results of these queries.

libpq is also the underlying engine for several other PostgreSQL application interfaces, including those written for C++, Perl, Python, Tcl and ECPG. So some aspects of libpq's behavior will be important to you if you use one of those packages. In particular, Section 34.14, Section 34.15 and Section 34.18 describe behavior that is visible to the user of any application that uses libpq.

Some short programs are included at the end of this chapter (Section 34.21) to show how to write programs that use libpq. There are also several complete examples of libpq applications in the directory src/test/examples in the source code distribution.

Client programs that use libpq must include the header file libpq-fe.h and must link with the libpq library.