Basically, it was a site with a medium amount of paid users. Probably 10-20k daily uniques. However, the nature and diversity of the data behind this site required thousands of tables and tens of thousands of stored procedures.
Since these queries were built over ~10 years with the expectation of being able to join any of the thousands of tables, it would now be a tremendous undertaking to perform any sort of sharding or other ways of distributing load (other than master-slave replication, which was used widely).
It's been a struggle to keep hardware up to pace with the desired growth of the company. Even with a dedicated data center and top of the line hardware, doubling their user base would probably require a significant architectural undertaking.
Had the site been designed to support an arbitrary amount of distributed database servers from day one, it would now be trivial to grow horizontally.
Since these queries were built over ~10 years with the expectation of being able to join any of the thousands of tables, it would now be a tremendous undertaking to perform any sort of sharding or other ways of distributing load (other than master-slave replication, which was used widely).
It's been a struggle to keep hardware up to pace with the desired growth of the company. Even with a dedicated data center and top of the line hardware, doubling their user base would probably require a significant architectural undertaking.
Had the site been designed to support an arbitrary amount of distributed database servers from day one, it would now be trivial to grow horizontally.