Introduction

FMTC uses a root and stores to structure its data.

There is generally a single root (which generally corresponds to a single backend), which contains multiple stores. Cached tiles can belong to multiple stores, which keeps duplication minimized.

The structures use the ambient backend when a method is invoked on it, not at construction time.

Therefore, it is possible to construct an FMTCStore/FMTCRoot (see below) before initialisation, but 'using' it will throw RootUnavailable.

Keep the number of stores small to improve performance!

FMTC isn't internally optimized to handle large numbers of stores within the database queries and processing, and algorithms often have polynomial time complexities based on the number of stores. This is because of the feature that tiles can belong to multiple stores, and therefore a lot of extra work is required to keep track of this all.