We need to shard our Tenants to support larger databases without those
large databases dominating our pageservers and/or requiring dedicated
pageservers.
This RFC aims to define an initial capability that will permit creating
large-capacity databases using a static configuration
defined at time of Tenant creation.
Online re-sharding is deferred as future work, as is offloading layers
for historical reads. However, both of these capabilities would be
implementable without further changes to the control plane or compute:
this RFC aims to define the cross-component work needed to bootstrap
sharding end-to-end.
