It is based on code already being used on the WordPress blogging website with multiple database servers.
WordPress MU only: add this line near the top of wp-config.php: define('WPMU', true);
Upload db.php to the /wp-content/ directory. At this point, HyperDB is active. It will use the database connection constants until you complete the final steps.
Upload db-settings.php in the directory that holds wp-config.php
Edit the db settings according to the directions in that file.
Add this line near the top of wp-config.php: require('db-settings.php');
Any value of WP_USE_MULTIPLE_DB will be ignored by HyperDB. If you wish to switch off multiple DB, remove the 'require' statement from step 5.
Here are some key features of "HyperDB":
· Read and write servers (replication)
· Local and remote datacenters
· Private and public networks
· Different tables on different databases/hosts
· Smart post-write master reads
· Failover for downed host
· Advanced statistics for profiling
· WordPress 2.3 or higher