Finding best caching strategy to optimise memory used with maxTtlIfError

[kdybicz]

At the moment, due to really simple approach for implementation of the maxTtlIfError in the http-data-source.ts cached data are sent over-the-wire and stored in the cache twice.

On this graphs you can see that this implementation (plus probably some other less optimised code - than in apollo-server-rest) is causing a huge, unexpected influx of data in our Redis instance.

I was wondering if anyone would have better ideas that might be used to improve the performance and reduce usage of cache memory and keep the behaviour of maxTtlIfError unchanged.