20.5 libmysqld, the Embedded MySQL Server Library

The embedded MySQL server library is NOT part of MySQL 5.0. It is part of previous editions and will be included in future versions, starting with MySQL 5.1. You can find appropriate documentation in the corresponding manuals for these versions. In this manual, only an overview of the embedded library is provided.

The embedded MySQL server library makes it possible to run a full-featured MySQL server inside a client application. The main benefits are increased speed and more simple management for embedded applications.

The embedded server library is based on the client/server version of MySQL, which is written in C/C++. Consequently, the embedded server also is written in C/C++. There is no embedded server available in other languages.

The API is identical for the embedded MySQL version and the client/server version. To change an old threaded application to use the embedded library, you normally only have to add calls to the following functions.

Table 20.3 MySQL Embedded Server Library Functions

Function

When to Call

mysql_library_init()

Call it before any other MySQL function is called, preferably early in the main() function.

mysql_library_end()

Call it before your program exits.

mysql_thread_init()

Call it in each thread you create that accesses MySQL.

mysql_thread_end()Call it before calling pthread_exit().

Then, link your code with libmysqld.a instead of libmysqlclient.a. To ensure binary compatibility between your application and the server library, be sure to compile your application against headers for the same series of MySQL that was used to compile the server library. For example, if libmysqld was compiled against MySQL 4.1 headers, do not compile your application against MySQL 5.1 headers, or vice versa.

The mysql_library_xxx() functions are also included in libmysqlclient.a to enable you to change between the embedded and the client/server version by just linking your application with the right library. See Section 20.6.7.40, “mysql_library_init()”.

One difference between the embedded server and the standalone server is that for the embedded server, authentication for connections is disabled by default. To use authentication for the embedded server, specify the --with-embedded-privilege-control option when you invoke configure to configure your MySQL distribution.