This document discusses different ways to migrate an existing database table to a sharded structure using the Spider storage engine in MariaDB. It covers using replication, triggers, Spider functions, and vertical partitioning. The replication method involves copying data to new tables, starting replication, and switching to the new structure. The trigger method uses triggers to copy data in real-time. Spider functions allow copying data without locks. Vertical partitioning splits the table across multiple servers based on column values.