18. The server of claim 13 further comprising: a command indicative of a plurality of tabular databases; a plurality of data collections for satisfying the received command; the application configured for: invoking the catalog corresponding to each of the identified data collections; and performing a join on the identified data collections for rendering a result responsive to the command.
13. The server of claim 12 wherein the catalog defines: an identity of, for each field in the collection, a type of data values populated for the field; if the field is a mixed type, a percentage of data values corresponding to each data type; a count of populated data values for each type; and for each data value, a reference to a location of the data value in the collection.