Magento has the feature of logging every request to its database, giving you insight into your visitors behaviour. But this is also including search-engines and if you are using a tool like Google Analytics, this logging is pointless. Learn how to disable it.
Within the Magento System Configuration under the Advanced tab, you have the option to disable the output of various Magento modules. Many Magento users think this actually disables the module. It does not. It only disables the output of that module. Logging is not considered output.
The proper way to disable the Mage_Log module would be to locate its XML-definition in the folder app/etc/modules and set the flag active to false. If you do that, your Magento site will crash. So don't do that. It doesn't work.
Within the Magento System Configuration under the Developer tab, there is also an option to disable logging. While it is a bit confusing, this is an entirely different type of logging: This logging is ment for developers, so debugging usage, while the logging we refer to in this blog is the logging of visitor-data for statistical usage. The two are not related.
The only real solution is to modify the Magento core. But instead of you hacking into the core, you can simply use our extension to do all the hard work for you: Our DisableLog extension allows you to quickly disable logging. And you have the choice. You can disable logging for all your visitors (if you are using Google Analytics or Piwik or something alike) or for just search-engines (if you don't want search-engines to flood your statistics).
Hope you find this useful.