connection.getDiff( query, availableQueries )

This determines the minimal amount of data that must be loaded from the base connection by going through each cached query (availableQueries) and doing a isSubset check and a query difference with the requested query (query).

If query is a subset of an availableSet, {cached: query} will be returned.

If query is neither a subset of, nor intersects with any availableQueries, {needed: query} is returned.

If query has an intersection with one or more availableQueries, a description of the difference that has the fewest missing elements will be returned. An example diff description looks like:

{
  needed: {start: 50, end: 99}, // the difference, the query that is not cached
  cached: {start: 0, end: 49}, // the intersection, the query that is cached
  count: 49 // the size of the needed query
}