The original binary log format was developed in MySQL 3.23. It changed in MySQL 4.0, and again in MySQL 5.0. This has consequences when you upgrade servers in a replication setup, as described in the section called “Upgrading a Replication Setup”.
As far as replication is concerned, any MySQL 4.1.x version and any 4.0.x version are identical, because they all use the same binary log format. Thus, any servers from these versions are compatible, and replication between them should work seamlessly. The exceptions to this compatibility is that versions from MySQL 4.0.0 to 4.0.2 were very early development versions that should not be used anymore. (These were the alpha versions in the 4.0 release series. Compatibility for them is still documented in the manual included with their distributions.)
The following table indicates master/slave replication compatibility between different versions of MySQL.
| Master | Master | Master | ||
| 3.23.33 and up | 4.0.3 and up or any 4.1.x | 5.0.0 | ||
| Slave | 3.23.33 and up | yes | no | no |
| Slave | 4.0.3 and up | yes | yes | no |
| Slave | 5.0.0 | yes | yes | yes |
As a general rule, we recommended using recent MySQL versions, because replication capabilities are continually being improved. We also recommend using the same version for both the master and the slave.