Caching

The library supports caching for collections and documents. A Firestore listener keeps the cache up to date when documents change, so updates are propagated across distributed instances automatically.

This avoids reading, and paying for, the same documents repeatedly. It is particularly useful for dictionaries, configuration and other data that changes rarely, and can reduce both cost and latency noticeably.

Caching is opt-in through cargo features:

• caching-memory for an in-memory cache, implemented with the moka cache library;
• caching-persistent for a persistent, disk backed cache, implemented with redb and protobuf.