Multisite Multi Database Plugin.

WordPress multisite is a feature in WordPress that allows users to create a network of multiple websites that share a common installation of WordPress. This feature allows the entire website in the network to be managed from a single set of login credentials.

Importance of WordPress Multisite
Users can create and manage multiple websites from a single installation of WordPress.
Multisite feature can be very useful for organizations or individuals who need to manage multiple websites or blogs.
It is easier to manage and maintain the resources (plugins, themes, etc). Fewer resources are required to create and manage multiple sites.
Because all of the sites in a WordPress multisite network share a single installation of WordPress, it can be easier to keep the installation up to date and secure.

Limitations multisite:
Before the development of multi-DB multisite plugin, it is not possible to use multiple databases with a WordPress multisite installation. WordPress multisite uses a single database to store all of the data for all of the sites in the network. This includes posts, pages, comments, users, and other types of content.
One major limitation of WordPress Multisite is that the database tables keep getting longer with more sites being added to the multisite network.

Importance of Multi-DB Multisite WordPress
The main feature of Multi-DB Multisite plugin is to fix the limitation of single database for multiple sites. The multi-db multisite plugin automates the creation of database and database tables for each of the sites created from the wordpress dashboard and front site.

Requirements for multisite multi-database:
The database user provided in the wp-config.php needs to have privileges to create databases.

Steps to install and run multisite multi-database plugin
1) Install and setup multisite.
2) Install and activate the multisite multi-database plugin plugin.
3) You can now create multisites