struct es_mba is an opaque data structure representing a database aggregator. An aggregator is a powerful high-level tool for aggregating, deriving and filtering data.
The interface allows you to aggregate various database values by one or more keys. Key and aggregate result fields are defined from database fields or from formulae derived from database fields.
Given a specification of keys and results, the aggregator automatically derives and executes a program, known as a query plan, against an input database definition and instance.
The aggregator interface is largely declarative and independent of the actual structure of the database used to source the data.
Data can be filtered or excluded from a query via formulae or through use of membership filters (struct es_mbm ).
|Copyright © 2012 by Richard Brooks|