This bulletin explains the layout of Clarion index and key files. Clarion Index and Key Files While Technical Bulletin #117, «Clarion Data File,» covered the layout of Clarion Professional Developer’s data files, it only touched on the subject of the index and key files that Professional Developer uses to access your data in a specific order. The purpose of this technical bulletin is to explain how Clarion’s key and index files are laid out.
This technical bulletin assumes a knowledge of basic data structures and the C programming language. While you don’t have to be a C guru to understand the material presented here, a passing knowledge helps, as C makes it easy to create many types of data structures.
As far as this discussion is concerned, there are NO internal differences between index and key files. Index files are simply key files that are not updated automatically by adding, deleting, of changing records in your data base. Also, this bulletin will not explain how you create key files, only how to read them. Our method of managing B+ Trees is proprietary and quite complicated. In all fairness, we can only support products that create key files using our own code. When you see a non-Clarion product that creates and/or maintains Clarion key files, it means they have licensed our code for use in their product. Читать далее