The key structure should be a template argument

[thompsonbry]

This would make it possible to reuse the library with different kinds of keys. It might mean moving further toward header mostly compilation.

[thompsonbry]

Closing as it will be addressed with variable length key support.

[laurynas-biveinis]

Let's close it once it's implemented, together with the varlen keys

[thompsonbry]

@laurynas-biveinis As agreed, I will leave this out of the variable length key refactor.

As a heads up when templating the key into the db types, please also template in a parameter to configure an initial capacity for the buffers used to encode/decode/buffer keys. This is for an "in the object" buffer to optimize away an allocation in the vast majority of cases. If the keys are longer than this capacity, an allocation will occur. Right now this is configured as a constexpr in art_common.hpp.