Add Redis Caching about dat

[elithrar]

Neat idea. I assume the implementation of Cache is to fall back to querying directly if the hash of the query (or query + args) does not exist in Redis?

I'd be curious to see the benchmarks for a "big set of cached results from Redis" vs. "big set of cached results from the DB" (given that Postgres caches too).

[mgutz]

Correct, the cache will get updated:

• entry does not exist (either new entry or redis expired it)
• invalidate is true