Dyntex.net Support Centre: MySQL Reference Manual p.605

<< previous page -- table of contents -- next page >>

Chapter_1

Chapter_2

Chapter_3

Chapter_4

Chapter_5

Return to Table of Contents

Table of Contents
1. General Information
2. MySQL Installation
3. Tutorial Introduction
4. Database Administration
5. MySQL Optimisation
6. MySQL Language Reference
7. MySQL Table Types
8. MySQL APIs
9. Extending MySQL

Chapter 8: MySQL APIs 605 Two threads can't send a query to the MySQL server at the same time on the same connection. In particular, you have to ensure that between a mysql_query() and mysql_store_result() no other thread is using the same connection. Many threads can access dierent result sets that are retrieved with mysql_store_ result(). If you use mysql_use_result, you have to ensure that no other thread is using the same connection until the result set is closed. However, it really is best for threaded clients that share the same connection to use mysql_store_result(). If you want to use multiple threads on the same connection, you must have a mutex lock around your mysql_query() and mysql_store_result() call combination. Once mysql_store_result() is ready, the lock can be released and other threads may query the same connection. If you program with POSIX threads, you can use pthread_mutex_lock() and pthread_mutex_unlock() to establish and release a mutex lock. You need to know the following if you have a thread that is calling MySQL functions which did not create the connection to the MySQL database: When you call mysql_init() or mysql_connect(), MySQL will create a thread specic variable for the thread that is used by the debug library (among other things). If you call a MySQL function, before the thread has called mysql_init() or mysql_ connect(), the thread will not have the necessary thread specic variables in place and you are likely to end up with a core dump sooner or later. The get things to work smoothly you have to do the following: 1. Call my_init() at the start of your program if it calls any other MySQL function before calling mysql_real_connect(). 2. Call mysql_thread_init() in the thread handler before calling any MySQL function. 3. In the thread, call mysql_thread_end() before calling pthread_exit(). This will free the memory used by MySQL thread specic variables. You may get some errors because of undened symbols when linking your client with libmysqlclient_r. In most cases this is because you haven't included the thread libraries on the link/compile line. 8.4.9 libmysqld, the Embedded MySQL Server Library 8.4.9.1 Overview of the Embedded MySQL Server Library The embedded MySQL server library makes it possible to run a full-featured MySQL server inside the client application. The main benets are increased speed and more simple man- agement for embedded applications. 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:

MySQL Reference Manual

Our Partners

SpiritHost - web hosting for spiritual and education sites
SpiritHit.com - Religious and Spiritual Portal

Return to Table of Contents	Back to top

Web Hosting: Manuals & FAQ's

1. Unix-Based Web Hosting
2. Unix Dedicated Servers
3. Windows Dedicated Servers
4. CuteFTP User’s Guide
5. CuteHTML User’s Guide
6. WS_FTP Pro User's Guide
7. Miva Order User's Guide
8. Miva Merchant User's Guide