[SkyMarshal]

Good comment, though one minor semantic nitpick:

> Make arrays (tables) of things and map between them via relations.

In relational algebra, the "table" is the relation, defining a set of related attributes (column headers) and fields (corresponding column values in each row, or tuple). The mappings between multiple tables/relations are operations. Operations (select, union, etc) take one or more relations as inputs, and return a new relation as the output.

While it does appear that the foreign-key links between tables/relations are the "relations" there, since they seem to define the way different sets of data relate to each other, but the original relation is the set of attributes within each table/relation.