Projection Management / Mappings

[jeremydaly]

Another issue that has crept up with large tables using lots of entities/facets, is the 20 attribute projection limit per GSI. I've used mappings in the past to use generic attribute names, thought I know this can be difficult to manage. Perhaps if the library had a way to indicate which GSIs each field needed to be projected to, then the mapping could be optimized. This might need to be a CLI feature, but I could see it being useful.

The other possibility is to add an "attribute id" of some sort to the entity/facet definition and then use that to determine which attributes to map data to. I think this would probably allow for quite a bit of future flexibility, but I'd need to test that out more.

This is another placeholder for now.