PostgreSQL

Table of Contents

33.1. Database Connection Control Functions

33.1.1. Connection Strings

33.1.2. Parameter Key Words

33.2. Connection Status Functions

33.3. Command Execution Functions

33.3.1. Main Functions

33.3.2. Retrieving Query Result Information

33.3.3. Retrieving Other Result Information

33.3.4. Escaping Strings for Inclusion in SQL Commands

33.4. Asynchronous Command Processing

33.5. Retrieving Query Results Row-by-Row

33.6. Canceling Queries in Progress

33.7. The Fast-Path Interface

33.8. Asynchronous Notification

33.9. Functions Associated with the COPY Command

33.9.1. Functions for Sending COPY Data

33.9.2. Functions for Receiving COPY Data

33.9.3. Obsolete Functions for COPY

33.10. Control Functions

33.11. Miscellaneous Functions

33.12. Notice Processing

33.13. Event System

33.13.1. Event Types

33.13.2. Event Callback Procedure

33.13.3. Event Support Functions

33.13.4. Event Example

33.14. Environment Variables

33.15. The Password File

33.16. The Connection Service File

33.17. LDAP Lookup of Connection Parameters

33.18. SSL Support

33.18.1. Client Verification of Server Certificates

33.18.2. Client Certificates

33.18.3. Protection Provided in Different Modes

33.18.4. SSL Client File Usage

33.18.5. SSL Library Initialization

33.19. Behavior in Threaded Programs

33.20. Building libpq Programs

33.21. 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 33.14, Section 33.15 and Section 33.18 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 33.21) 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.

If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.

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