From Ingres Community Wiki

Abstract Data Facility Overview

Introduction

The Abstract Data Facility (ADF) is one of the major components of the Ingres database server. It defines the supported data types in an Ingres database, as well as the operators, functions and coercions that may be applied to instances of the types. It is also the expression evaluation engine for Ingres, generating and executing an internal code form for any expression (simple projections, arithmetic expressions, Boolean logic) required for the evaluation of a query. It also houses the logic required to implement the Object Management Extension (OME) of Ingres that allows the definition and manipulation of user defined object classes in an Ingres database.

ADF is also a component of most Ingres front end clients. In host language embedded SQL, ADF is used to coerce columns in the result rows of queries into the requested data types of the receiving host language variables. Various front end tools (OpenROAD, ABF, Report Writer) also use ADF as an expression evaluation engine.

More Detailed Information

The attached document is a work-in-progress. More material will be added over time.