MySQL 5.0从5.0.27以后，单数版本为社区版。双数版本号为企业版。如果您还不想从5.0升级到5.1的话，可以继续使用5.0的这个版本。主要还是以安全更新和bug fix居多。
官方change-log网址：http://dev.mysql.com/doc/refman/5.0/en/releasenotes-cs-5-0-75.html
简要说明：
Functionality added or changed:
-
Security Enhancement: To enable stricter control over the location from which user-defined functions can be loaded, the
plugin_dirsystem variable has been backported from MySQL 5.1. If the value is non-empty, user-defined function object files can be loaded only from the directory named by this variable. If the value is empty, the behavior that is used prior to the inclusion ofplugin_dirapplies: The UDF object files must be located in a directory that is searched by your system's dynamic linker. (Bug#37428) -
Previously, index hints did not work for
FULLTEXTsearches. Now they work as follows:For natural language mode searches, index hints are silently ignored. For example,
IGNORE INDEX(i)is ignored with no warning and the index is still used.For boolean mode searches, index hints are honored. (Bug#38842)